RESUMEN

Background: Systemic fungal infections and specifically invasive aspergillosis (IA) are associated with a high morbi-mortality rate in patients with hematologic malignancies. Itraconazole kinetic studies show that plasma levels are not satisfactory, even though there is a reduction of the severity in clinical cases. Aim: To evaluate the results of oral prophylaxis with high dose itraconazole, 400 mg bid, among patients with adult acute leukemia. Material and Methods: Prospective analysis of 93 high risk febrile episodes (with an absolute neutrophil count of less than 500 x mm3 for more 10 days), that occurred in 76 patients. Results: Seventy five percent of episodes occurred in patients with acute myeloid leukemia and 25 percent in patients with acute lymphoblastic leukemia. Fifty two percent occurred during the induction of chemotherapy. Median duration of severe neutropenia was 21 days (range 10-48). Median duration of itraconazole prophylaxis was 17 days (range 6-34). A low frequency of invasive fungal infections was observed (17 percent). According to diagnostic criteria, 5 percent of episodes corresponded to persistent fever , 1 percent and 11 percent of episodes, to probable or possible IA, respectively. No confirmed or proven IA was observed. Mortality of IA was 18 percent. No serious adverse events due to itraconazole were observed. Conclusions: The use of high dose itraconazole prophylaxis in adult patients with acute leukemia and severe neutropenia was associated to low incidence and mortality of invasive mycoses.

Asunto(s)

Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Antifúngicos/administración & dosificación , Itraconazol/administración & dosificación , Leucemia Mieloide Aguda/tratamiento farmacológico , Micosis/prevención & control , Neutropenia/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Enfermedad Aguda , Administración Oral , Antifúngicos/efectos adversos , Aspergilosis/prevención & control , Fiebre/tratamiento farmacológico , Itraconazol/efectos adversos , Neutropenia/inducido químicamente , Estudios Prospectivos , Aspergilosis Pulmonar/prevención & control

RESUMEN

BACKGROUND: Systemic fungal infections and specifically invasive aspergillosis (IA) are associated with a high morbi-mortality rate in patients with hematologic malignancies. Itraconazole kinetic studies show that plasma levels are not satisfactory, even though there is a reduction of the severity in clinical cases. AIM: To evaluate the results of oral prophylaxis with high dose itraconazole, 400 mg bid, among patients with adult acute leukemia. MATERIAL AND METHODS: Prospective analysis of 93 high risk febrile episodes (with an absolute neutrophil count of less than 500 x mm3 for more 10 days), that occurred in 76 patients. RESULTS: Seventy five percent of episodes occurred in patients with acute myeloid leukemia and 25% in patients with acute lymphoblastic leukemia. Fifty two percent occurred during the induction of chemotherapy. Median duration of severe neutropenia was 21 days (range 10-48). Median duration of itraconazole prophylaxis was 17 days (range 6-34). A low frequency of invasive fungal infections was observed (17%). According to diagnostic criteria, 5% of episodes corresponded to persistent fever , 1% and 11% of episodes, to probable or possible IA, respectively. No confirmed or proven IA was observed. Mortality of IA was 18%. No serious adverse events due to itraconazole were observed. CONCLUSIONS: The use of high dose itraconazole prophylaxis in adult patients with acute leukemia and severe neutropenia was associated to low incidence and mortality of invasive mycoses.

Asunto(s)

Antifúngicos/administración & dosificación , Itraconazol/administración & dosificación , Leucemia Mieloide Aguda/tratamiento farmacológico , Micosis/prevención & control , Neutropenia/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Enfermedad Aguda , Administración Oral , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antifúngicos/efectos adversos , Aspergilosis/prevención & control , Femenino , Fiebre/tratamiento farmacológico , Humanos , Itraconazol/efectos adversos , Masculino , Persona de Mediana Edad , Neutropenia/inducido químicamente , Estudios Prospectivos , Aspergilosis Pulmonar/prevención & control , Adulto Joven

RESUMEN

We previously reported in a rat cortical collecting duct cell line (RCCD(1)) that the presence of aquaporin 2 (AQP2) in the cell membrane is critical for the rapid activation of regulatory volume decrease mechanisms (RVD) (Ford et al. Biol Cell 97: 687-697, 2005). The aim of our present work was to investigate the signaling pathway that links AQP2 to this rapid RVD activation. Since it has been previously described that hypotonic conditions induce intracellular calcium ([Ca(2+)](i)) increases in different cell types, we tested the hypothesis that AQP2 could have a role in activation of calcium entry by hypotonicity and its implication in cell volume regulation. Using a fluorescent probe technique, we studied [Ca(2+)](i) and cell volume changes in response to a hypotonic shock in WT-RCCD(1) (not expressing aquaporins) and in AQP2-RCCD(1) (transfected with AQP2) cells. We found that after a hypotonic shock only AQP2-RCCD(1) cells exhibit a substantial increase in [Ca(2+)](i). This [Ca(2+)](i) increase is strongly dependent on extracellular Ca(2+) and is partially inhibited by thapsigargin (1 muM) indicating that the rise in [Ca(2+)](i) reflects both influx from the extracellular medium and release from intracellular stores. Exposure of AQP2-RCCD(1) cells to 100 muM gadolinium reduced the increase in [Ca(2+)](i) suggesting the involvement of a mechanosensitive calcium channel. Furthermore, exposure of cells to all of the above described conditions impaired rapid RVD. We conclude that the expression of AQP2 in the cell membrane is critical to produce the increase in [Ca(2+)](i) which is necessary to activate RVD in RCCD(1) cells.

Asunto(s)

Acuaporina 2/metabolismo , Calcio/metabolismo , Tamaño de la Célula/efectos de los fármacos , Soluciones Hipotónicas/farmacología , Animales , Acuaporina 2/genética , ATPasas Transportadoras de Calcio/antagonistas & inhibidores , Línea Celular , Gadolinio/farmacología , Espacio Intracelular/metabolismo , Ratas , Tapsigargina/farmacología , Transfección

RESUMEN

T84 is an established cell line expressing an enterocyte phenotype whose permeability properties have been widely explored. Osmotic permeability (POSM), hydraulic permeability (PHYDR) and transport-associated net water fluxes (JW-transp), as well as short-circuit current (ISC), transepithelial resistance (RT), and potential difference (deltaVT) were measured in T84 monolayers with the following results: POSM 1.3 +/- 0.1 cm.s-1 x 10-3; PHYDR 0.27 +/- 0.02 cm.s-1; RT 2426 +/- 109 omega.cm2, and deltaVT 1.31 +/- 0.38 mV. The effect of 50 microM 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a "net Cl- secretory agent", on T84 cells was also studied. We confirm the reported important increase in ISC induced by DCEBIO which was associated here with a modest secretory deltaJW-transp. The present results were compared with those reported using the same experimental approach applied to established cell lines originating from intestinal and renal epithelial cells (Caco-2, LLC-PK1 and RCCD-1). No clear association between PHYDR and RT could be demonstrated and high PHYDR values were observed in an electrically tight epithelium, supporting the view that a "water leaky" barrier is not necessarily an "electrically leaky" one. Furthermore, the modest secretory deltaJW-transp was not consistent with previous results obtained with RCCD-1 cells stimulated with vasopressin (absorptive fluxes) or with T84 cells secreting water under the action of Escherichia coli heat stable enterotoxin. We conclude that, while the presence of aquaporins is necessary to dissipate an external osmotic gradient, coupling between water and ion transport cannot be explained by a simple and common underlying mechanism.

Asunto(s)

Células Epiteliales/metabolismo , Presión Hidrostática , Ósmosis/fisiología , Agua/metabolismo , Línea Celular/metabolismo , Electrofisiología , Células Epiteliales/fisiología , Humanos , Potenciales de la Membrana/fisiología , Concentración Osmolar , Permeabilidad

RESUMEN

T84 is an established cell line expressing an enterocyte phenotype whose permeability properties have been widely explored. Osmotic permeability (P OSM), hydraulic permeability (P HYDR) and transport-associated net water fluxes (J W-transp), as well as short-circuit current (I SC), transepithelial resistance (R T), and potential difference (deltaV T) were measured in T84 monolayers with the following results: P OSM 1.3 ± 0.1 cm.s-1 x 10-3; P HYDR 0.27 ± 0.02 cm.s-1; R T 2426 ± 109 omega.cm², and deltaV T 1.31 ± 0.38 mV. The effect of 50 æM 5,6-dichloro-1-ethyl-1,3-dihydro-2H-benzimidazol-2-one (DCEBIO), a "net Cl- secretory agent", on T84 cells was also studied. We confirm the reported important increase in I SC induced by DCEBIO which was associated here with a modest secretory deltaJ W-transp. The present results were compared with those reported using the same experimental approach applied to established cell lines originating from intestinal and renal epithelial cells (Caco-2, LLC-PK1 and RCCD-1). No clear association between P HYDR and R T could be demonstrated and high P HYDR values were observed in an electrically tight epithelium, supporting the view that a "water leaky" barrier is not necessarily an "electrically leaky" one. Furthermore, the modest secretory deltaJ W-transp was not consistent with previous results obtained with RCCD-1 cells stimulated with vasopressin (absorptive fluxes) or with T84 cells secreting water under the action of Escherichia coli heat stable enterotoxin. We conclude that, while the presence of aquaporins is necessary to dissipate an external osmotic gradient, coupling between water and ion transport cannot be explained by a simple and common underlying mechanism.

Asunto(s)

Humanos , Células Epiteliales/metabolismo , Presión Hidrostática , Ósmosis/fisiología , Agua/metabolismo , Línea Celular/metabolismo , Electrofisiología , Células Epiteliales/fisiología , Potenciales de la Membrana/fisiología , Concentración Osmolar , Permeabilidad

RESUMEN

Transition from antidiuresis to diuresis exposes cortical collecting duct cells (CCD) to asymmetrical changes in environment osmolality, inducing an osmotic stress, which activates numerous membrane-associated events. The aim of the present work was to investigate, either in the presence or not of AQP2, the transepithelial osmotic water permeability (P(osm)) following cell exposure to asymmetrical hyper- or hypotonic gradients. For this purpose, transepithelial net volume fluxes were recorded every minute in two CCD cell lines: one not expressing AQPs (WT-RCCD(1)) and another stably transfected with AQP2 (AQP2-RCCD(1)). Our results demonstrated that the rate of osmosis produced by a given hypotonic shock depends on the gradient direction (osmotic rectification) only in the presence of apical AQP2. In contrast, hypertonic shocks elicit P(osm) rectification independently of AQP2 expression, and this phenomenon may be linked to modulation of basolateral membrane permeability. No asymmetry in transepithelial resistance was observed under hypo- or hypertonicity, indicating that rectification cannot be attributed to a shunt through the tight junction path. We conclude that osmotic rectification may be explained in terms of dynamical changes in membrane permeability probably due to activation/incorporation of AQPs or transporters to the plasma membrane via some mechanism triggered by osmolality.

Asunto(s)

Acuaporina 2/metabolismo , Permeabilidad de la Membrana Celular/fisiología , Células Epiteliales/metabolismo , Túbulos Renales Colectores/metabolismo , Equilibrio Hidroelectrolítico/fisiología , Animales , Línea Celular , Presión Osmótica , Ratas

RESUMEN

The Na+/H+ exchanger (NHE) constitutes a gene family containing several isoforms that display different membrane localization and are involved in specialized functions. Although basolateral NHE-1 activity was described in the cortical collecting duct (CCD), the localization and function of other NHE isoforms is not yet clear, This study examines the expression, localization, and regulation of NHE isoforms in a rat cortical collecting duct cell line (RCCD1) that has previously been shown to be a good model of CCD cells. Present studies demonstrate the presence of NHE-1 and NHE-2 isoforms, but not NHE-3 and NHE-4, in RCCD1 cells. Cell monolayers, grown on permeable filters, were placed on special holders allowing independent access to apical and basolateral compartments. Intracellular pH (pHi) regulation was spectrofluorometrically studied in basal conditions and after stimulation by NH4Cl acid load or by a hyperosmotic shock. In order to differentiate the roles of NHE-1 and NHE-2, we have used HOE-694, an inhibitor more selective for NHE-1 than for NHE-2. The results obtained strongly suggest that NHE-1 and NHE-2 are expressed in the basolateral membrane but that they have different roles: NHE-1 is responsible for pHi recovery after an acid load and NHE-2 is mainly involved in steady-state pHi and cell volume regulation.

Asunto(s)

Túbulos Renales Colectores/química , Túbulos Renales Colectores/fisiología , Intercambiadores de Sodio-Hidrógeno/química , Intercambiadores de Sodio-Hidrógeno/fisiología , Animales , Línea Celular , Tamaño de la Célula/fisiología , Regulación de la Expresión Génica , Homeostasis/fisiología , Concentración de Iones de Hidrógeno , Concentración Osmolar , Presión Osmótica , Isoformas de Proteínas/química , Isoformas de Proteínas/fisiología , Ratas , Valores de Referencia , Reproducibilidad de los Resultados , Sensibilidad y Especificidad

RESUMEN

Transepithelial water movements and arginine-vasopressin (AVP)-associated ones were studied in a renal cell line established from a rat cortical collecting duct (RCCD(1)). Transepithelial net water fluxes (J(w)) were recorded every minute in RCCD(1) monolayers cultured on permeable supports. Spontaneous net water secretion was observed, which was inhibited by serosal bumetanide (10(-5) m), apical glibenclamide (10(-4) m) and apical BaCl(2) (5 x 10(-3) m). RT-PCR, RNAse protection and/or immunoblotting experiments demonstrated that known renal aquaporins (AQP1, AQP2, AQP3, AQP4, AQP6 and AQP7) were not expressed in RCCD(1) cells. AVP stimulates cAMP production and sodium reabsorption in RCCD(1) cells. We have now observed that AVP significantly reduces the spontaneous water secretory flux. The amiloride-sensitive AVP-induced increase in short-circuit current (I(sc)) was paralleled by a simultaneous modification of the observed J(w): both responses had similar time courses and half-times (about 4 min). On the other hand, AVP did not modify the osmotically driven J(w) induced by serosal hypertonicity. We can conclude that: (i) transepithelial J(w) occurs in RCCD(1) cells in the absence of known renal aquaporins; (ii) the "water secretory component" observed could be linked to Cl- and K = secretion; (iii) the natriferic response to AVP, preserved in RCCD(1) cells, was associated with a change in net water flux, which was even observed in absence of AQP2, AQP3 or AQP4 and (iv) the hydro-osmotic response to AVP was completely lost.

Asunto(s)

Arginina Vasopresina/farmacología , Túbulos Renales Colectores/efectos de los fármacos , Túbulos Renales Colectores/fisiología , Animales , Acuaporinas/genética , Acuaporinas/fisiología , Secuencia de Bases , Bumetanida/farmacología , Línea Celular , Cartilla de ADN/genética , Diuresis/efectos de los fármacos , Diuresis/fisiología , Expresión Génica , Gliburida/farmacología , Transporte Iónico/efectos de los fármacos , Corteza Renal/efectos de los fármacos , Corteza Renal/fisiología , Natriuresis/efectos de los fármacos , Natriuresis/fisiología , Presión Osmótica , Ratas , Agua/fisiología

RESUMEN

El adecuado control de la hidatidosis en general, requiere conocer algunos aspectos relacionados con la supervivencia de los agentes infectantes, especialmente de los escólices. El objetivo de este trabajo, es evaluar la viabilidad de los escólices de quistes hidatídicos humanos de localización hepática. Estudiar la asociación entre las características clínicas al momento de la cirugía y el porcentaje de viabilidad de los escólices. Los criterios de viabilidad utilizados fueron: forma ovoide, invaginados, ganchos rostrales y corpúsculos calcáreos intactos, movimientos vibratorios presentes y ausencia de tinción con colorantes vitales. Los criterios para certificar mortalidad de los escólices fueron dos o más de los siguientes hechos: inmovilidad, alteración de los ganchos rostrales y de los corpúsculos calcáreos, rotura de membrana y pérdida de la forma ovoide y fácil tinción con el colorante vital (azul de tripan al 1,5 por ciento). Se estudiaron de esta forma 16 quistes, con un diámetro promedio de 16,2 cm. Siete lesiones (44 por ciento) de tipo univesicular, 5 (31 por ciento) multivesiculares y 4 (25 por ciento) quistes abscedados. En 7 oportunidades (44 por ciento), se evidenció comunicación a la vía biliar; y se constató viabilidad en 9 de los 16 quistes (56 por ciento). Las muestras con mayor porcentaje de escólices viables fueron los quistes multivesiculares, principalmente a expensas de las vesículas hijas. Se constató que los quistes multivesiculares eran viables en el 100 por ciento de los casos, a diferencia de los univesiculares con un 57 pir ciento y los abscedados con 0 por ciento (p= 0,01)

Asunto(s)

Humanos , Echinococcus/aislamiento & purificación , Equinococosis Hepática/parasitología , Técnicas In Vitro , Conductos Biliares/parasitología , Echinococcus/efectos de los fármacos , Echinococcus/crecimiento & desarrollo , Echinococcus/patogenicidad , Hígado/parasitología , Técnicas Histológicas , Supervivencia Tisular

RESUMEN

Minute-by-minute net water fluxes (Jw) were measured across the isolated rectal epithelium in rats and rabbits. Five minutes after a serosal (but not mucosal) hypertonic challenge (plus 200 mosmol/l) a significant increase in the basal Jw was recorded in both species [deltaJw, microl min(-1) cm(-2): 0.40+/-0.06 (rats); 0.45+/-0.10 (rabbits)]. At the same time, most epithelial cells shrank markedly while the intercellular spaces were wide open (electron microscopy studies). In freeze-fracture studies multi-strand tight-junction structures (only slightly modified by serosal hypertonicity in rabbits) were observed in control conditions. No structural changes were observed after mucosal hypertonicity (both in rats and rabbits). Immunohistochemical studies showed the expression of aquaporin 3 (AQP3) at the basolateral membrane of epithelial cells in the rat. A first conclusion is that the epithelium of the mammalian rectum is a highly polarized, aquaporin-3-containing, water permeability structure. The Jw increase induced by serosal hypertonicity was sensitive to mercurial agents in both species and no changes in unidirectional [14C]mannitol fluxes (Ps) or transepithelial resistance (RT) were observed during this Jw increase. These observations suggest a transcellular route for the osmotically induced increase in water fluxes. In the rabbit rectum the initial Jw response, associated with serosal hypertonicity, was a transient one. It was followed by a second, slow and HgCl2-sensitive Jw increase (a transient peak in paracellular mannitol permeability was also observed). A second conclusion is that serosal hypertonicity induces an increase in transcellular water permeability in both rat and rabbit rectum.

Asunto(s)

Soluciones Hipertónicas , Permeabilidad , Recto/metabolismo , Recto/ultraestructura , Agua/metabolismo , Animales , Acuaporina 3 , Acuaporinas/análisis , Tamaño de la Célula , Impedancia Eléctrica , Epitelio/química , Epitelio/metabolismo , Epitelio/ultraestructura , Técnica de Fractura por Congelación , Inmunohistoquímica , Masculino , Manitol/metabolismo , Cloruro de Mercurio/farmacología , Microscopía Electrónica , Concentración Osmolar , Conejos , Ratas , Uniones Estrechas/ultraestructura

RESUMEN

Important functional and structural modifications occur in mammalian oocytes during their arrival to maturity. In this process, oocytes switch from a high activity level, implying an important metabolic rate and a coordinated movement of water and solutes, to a lower functional state. The aim of this work was to study the mechanisms involved in water movements during oocyte arrival to maturity. Volume changes, induced by an osmotic gradient, were followed by video microscopy in rat oocytes. The water osmotic permeability (P(osm)) of immature oocytes (proestrus) was sensitive to HgCl(2) and phloretin. In contrast, mature oocytes (estrus) had a reduced P(osm) that was not sensitive to these compounds. When proestrus oocytes were incubated in vitro at 37 degrees C they spontaneously arrived at maturity and its P(osm) decreased between four and six hours of incubation. RT-PCR experiments were performed using specific primers for all rat aquaporins that had been cloned. We found that aquaporin-9 transcript (AQP9) is present in proestrus oocytes but not in estrus oocytes. AQP9 has been recently described as a "broad selective channel" responsible for solute and water transfers in highly active cells. Our experiments showed that proestrus oocytes, but not estrus, are permeable to mannitol. It is concluded that during the process of maturation, P(osm) decreases and AQP9 transcripts disappear. We report here the first study correlating water permeability and aquaporin mRNA expression in mammalian oocytes.

Asunto(s)

Acuaporinas/biosíntesis , Agua/metabolismo , Animales , Acuaporinas/genética , Permeabilidad de la Membrana Celular , Diabetes Mellitus/metabolismo , Expresión Génica , Oocitos/metabolismo , ARN Mensajero , Ratas , Ratas Wistar

RESUMEN

Background: One of the most important factors involved in the pathophysiology of gastroesophageal reflux disease (GERD) is the lower esophageal sphincter rest pressure (LESRP), but these patients can have esophageal motor disorders (EMD). Aim: To assess an association between LESRP and the appearance of EMD in patients with GERD. Subjects and methods: A cross-sectional study was conducted in 229 patients with GERD and 49 healthy controls. Forty five patients with LESRP < 6 mmHg and a mean age of 49 years were assigned to group 1, 128 patients with a LESRP between 6 and 12 mmHg and mean age of 47 years were assigned to group 2, 56 patients with a a LESRP >12 mmHg and a mean age of 47 years were assigned to group 3 and group 4 was conformed by 49 healthy subjects aged 40 years old. Esophageal manometry was performed using previously published techniques. Results: There was a significant association between LESRP, waves amplitude and the frequency of tertiary waves. Conclusions: Resting lower esophageal sphincter pressure is inversely proportional to the presence of esophageal motor disorders in patients with gastroesophageal reflux disease

Asunto(s)

Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Reflujo Gastroesofágico/etiología , Trastornos de la Motilidad Esofágica/complicaciones , Metabolismo Basal , Manometría , Hipotonía Muscular/fisiopatología , Trastornos de la Motilidad Esofágica/fisiopatología , Unión Esofagogástrica/fisiopatología

RESUMEN

The biophysical models describing the structure of water pores or channels have evolved, during the last forty years, from a pure 'black box' approach to a molecular based proposal. The initial 'sieving pore' in which water and other molecules were moving together was replaced by a more restrictive model, where water is moving alone in a 'single file' mode. Aquaporins discovery and cloning [G.M. Preston, T.P. Carroll, W.B. Guggino, P. Agre, Science 256 (1992) 365] leaded to the 'hour-glass model' and other alternative proposals, combining information coming from molecular biology experiments and two dimensional crystallography. Concerning water transfers in epithelial barriers the problem is quite complex, because there are at least two alternative pathways: paracellular and transcellular and three different driving forces: hydrostatic pressure, osmotic pressure or 'transport coupled' movements. In the case of ADH-sensitive epithelia it is more or less accepted that regulated water channels (AQP2), that can be inserted in the apical membrane, coexist with basolateral resident water channels (AQP3). The mechanism underlying the so-called 'transport associated water transfer' is still controversial. From the classical standing gradient model to the ion-water co-transport, different hypothesis are under consideration. Coming back to hormonal regulations, other than the well-known regulation by neuro-hypophysis peptides, a steroid second messenger, progesterone, has been recently proposed [P. Ford, G. Amodeo, C. Capurro, C. Ibarra, R. Dorr, P. Ripoche, M. Parisi, Am. J. Physiol. 270 (1996) F880].

RESUMEN

The ovarian oocytes from Bufo arenarum (BAO) but not those from Xenopus laevis (XLO) would have water channels (WC). We now report that the injection of the mRNA from BAO into the oocytes from XLO increased their water osmotic permeability (Pi) (reduced by 0.3 mM HgCl2 and reversed by 5 mM beta-mercaptoethanol). A 30-min challenge with progesterone induced, 18 h later, a reduction of the mercury-sensitive fraction of Pf in the BAO (but not in XLO). The mRNA from BAO pretreated with progesterone lost its capacity to induce WC in the XLO, but the hormone did not affect the expression of the WC in XLO previously injected with the mRNA from BAO. Pf was also measured in urinary bladders of BAO. Eighteen hours after a challenge with progesterone, a reduction in the hydrosmotic response to oxytocin was observed. Finally, the mRNA from the urinary bladder of BAO was injected into XLO. An increase in Pf was observed. This was not the case if, before the mRNA extraction, the bladders were treated with progesterone. We conclude that the BAO WC share progesterone sensitivity with the oxytocin-regulated water channel present in the toad urinary bladder.

Asunto(s)

Canales Iónicos/efectos de los fármacos , Oocitos/metabolismo , Progesterona/farmacología , Vejiga Urinaria/metabolismo , Agua/metabolismo , Animales , Bufo arenarum , Femenino , Inyecciones , Canales Iónicos/genética , Ovario/citología , Oxitocina/farmacología , Permeabilidad , ARN Mensajero/administración & dosificación , ARN Mensajero/aislamiento & purificación , Transcripción Genética , Vejiga Urinaria/química , Xenopus laevis

RESUMEN

The net absorptive water flux (Jw), the transepithelial potential difference (PD) and the short-circuit current (Isc) were simultaneously measured in the human small intestine in vitro with the following results: 1) An absorptive Jw was observed when the jejunum or the ileum were mounted between two identical standard solutions in the presence of an hydrostatic pressure gradient (delta P) of 13 cm of water (mucosal side positive). 2) The absorptive Jw was a linear function of the applied delta P or the imposed osmotic transepithelial gradient (delta Osm) in both intestinal segments. The hydrostatic (Phydr) and osmotic (Posm) permeabilities to water for jejunum and ileum were: 0.349 +/- 0.049 cm/s vs. 0.156 +/- 0.022 cm/s and 0.0012 +/- 0.0001 cm/s vs. 0.0019 +/- 0.0003, respectively. 3) A fraction of this absorptive Jw was independent of the presence of any hydrostatic, osmotic or chemical gradient and represented the transport associated to movement of water (Jwt). 4) PD and Isc values were similar in the jejunum and in the ileum but the transepithelial resistance (Rt) was significantly greater in ileum than in jejunum. 5) 2 micrograms/ml of E. coli heat-stable enterotoxin (STa) caused a significant inhibition of the absorptive Jw without modification of Phydr, Posm or Isc. 6) After STa treatment, the absorptive Jwt reverted to a secretory one in the jejunum. In the ileum, STa action caused a 48% decrease in the absorptive Jwt values.

Asunto(s)

Toxinas Bacterianas/farmacología , Enterotoxinas/farmacología , Intestino Delgado/efectos de los fármacos , Intestino Delgado/fisiología , Agua/metabolismo , Animales , Proteínas de Escherichia coli , Humanos , Técnicas In Vitro , Permeabilidad/efectos de los fármacos

RESUMEN

The water permeability properties of ovarian oocytes from Xenopus laevis and Bufo arenarum, a toad species found in the Buenos Aires region, were studied. We report that: (i) the water osmotic permeability (Pf, cm/sec x 10(-4)) was significantly higher in Bufo (6 degrees C = 12.3 +/- 2.4; 18 degrees C = 20.8 +/- 4.8) than in Xenopus oocytes (6 degrees C = 5.3 +/- 0.3; 18 degrees C = 6.2 +/- 1.6). The corresponding water diffusion permeability values (Pd, cm/sec x 10(-4)) were: Xenopus = 2.3 +/- 0.3 (6 degrees C) and 4.8 +/- 0.7 (18 degrees C); Bufo = 2.7 +/- 0.4 (6 degrees C) and 6.0 +/- 0.5 (18 degrees C). (ii) Amphotericin B increased the Pf and Pd values. The observed delta Pf/delta Pd ratio was not significantly different from the expected results (n = 3), after amphotericin B incorporation in both species. This means that the influence of unstirred layers and other potential artifactual compounds did not significantly affect our experimental results. (iii) Preincubation with gramicidin during 12 hr induced a clear increase in the oocyte volume. After that, a hypotonic shock only slightly increased the oocyte volume. Conversely, a hypertonic challenge induced a volume change significantly higher than the one observed in control conditions. (iv) Mercury ions did not affect the osmotic permeability in Xenopus oocytes but clearly inhibited, in a reversible way, the osmotic permeability in oocytes from B. arenarum. (v) Mercury ions did not reduce Pd values in either species.(ABSTRACT TRUNCATED AT 250 WORDS)

Asunto(s)

Bufo arenarum/fisiología , Permeabilidad de la Membrana Celular/fisiología , Oocitos/citología , Ovario/citología , Agua/fisiología , Xenopus laevis/fisiología , Anfotericina B/farmacología , Animales , Membrana Celular/fisiología , Membrana Celular/ultraestructura , Permeabilidad de la Membrana Celular/efectos de los fármacos , Femenino , Gramicidina/metabolismo , Gramicidina/farmacología , Mercurio/farmacología , Oocitos/fisiología , Oocitos/ultraestructura , Ósmosis/efectos de los fármacos , Ósmosis/fisiología

RESUMEN

The transepithelial net water movement (Jw) was minute by minute recorded in the cecum of Wistar rats adapted to a high potassium diet (HKD). The potential difference (PD), short circuit current (SCC) and unidirectional 22Na, 36Cl, and 89Rb fluxes were also measured. The hydrostatic and osmotic permeabilities were not modified by potassium adaptation when a standard bicarbonate buffer was employed. Potassium adaptation implicated the development of a secretory, transport-associated Jw (Jwt), associated to an increase in transepithelial PD, SCC and net sodium transport. Contrary to the case of control rats, no net chloride transport was observed in HKD rats. The secretory Jwt compensated, in the presence of sodium, chloride and bicarbonate, an absorptive Jwt. Water secretion was coupled to net potassium secretion. Replacement of chloride by sulphate ions was paralleled by the development of a net absorptive Jw and by increases in the transepithelial Pd and hydrostatic permeability. Replacement of the bicarbonate buffer by a tris-hepes buffer made drop both the observed absorptive Jw and PD amiloride sensitive Na+ entry was observed.

Asunto(s)

Ciego/fisiología , Potasio/administración & dosificación , Equilibrio Hidroelectrolítico , Animales , Permeabilidad de la Membrana Celular , Masculino , Ratas , Ratas Wistar , Agua/metabolismo

RESUMEN

Se midió a minuto el movimiento neto de agua transepitelial (Jw) en el ciego de ratas Wistar adaptadas a una dieta con alto potasio (HKD). También se midió la diferencia de potencial (PD), la corriente de cortocircuito (SCC) y los flujos unidireccionales de 22Na, 36Cl 89Rb. Cuando se utilizó un buffer bicarbonato, las permeabilidades hidrostática y osmótica no se modificaron con la adaptación al potasio. La adaptación al potasio implicó el desarrollo de un Jw secretorio asociado al transporte (Jw), relacionado con un incremento en la PD transepitelial, la SCC y el transporte neto de sodio. Contrariamente al caso de las ratas controles, no se observó ningún transporte neto de cloruro en las ratas HKD. En la presencia de sodio, cloruro y bicarbonato, el Jwt secretorio compensó un Jwt absortivo. La secreción de agua se acopló a una secreción neta de potasio. El reemplazo de iones cloruro por iones sulfato estuvo acompañado por el desarrollo de un Jw neto absortivo y por incrementos en la PD transepitelial y la permeabilidad hidrostática. El reemplazo del buffer bicarbonato por un buffer tris-hepes hizo decaer el Jw absortivo observado y la PD. Por último, se observó el cambio de una reabsorción de NaCI no electrogénica a una entrada electrogénica de Na+ sensible al amiloride (AU)

Asunto(s)

Ratas , Animales , Masculino , Ciego/fisiología , Equilibrio Hidroelectrolítico , Potasio/administración & dosificación , Permeabilidad de la Membrana Celular , Agua/metabolismo , Ratas Wistar

RESUMEN

Se midió a minuto el movimiento neto de agua transepitelial (Jw) en el ciego de ratas Wistar adaptadas a una dieta con alto potasio (HKD). También se midió la diferencia de potencial (PD), la corriente de cortocircuito (SCC) y los flujos unidireccionales de 22Na, 36Cl 89Rb. Cuando se utilizó un buffer bicarbonato, las permeabilidades hidrostática y osmótica no se modificaron con la adaptación al potasio. La adaptación al potasio implicó el desarrollo de un Jw secretorio asociado al transporte (Jw), relacionado con un incremento en la PD transepitelial, la SCC y el transporte neto de sodio. Contrariamente al caso de las ratas controles, no se observó ningún transporte neto de cloruro en las ratas HKD. En la presencia de sodio, cloruro y bicarbonato, el Jwt secretorio compensó un Jwt absortivo. La secreción de agua se acopló a una secreción neta de potasio. El reemplazo de iones cloruro por iones sulfato estuvo acompañado por el desarrollo de un Jw neto absortivo y por incrementos en la PD transepitelial y la permeabilidad hidrostática. El reemplazo del buffer bicarbonato por un buffer tris-hepes hizo decaer el Jw absortivo observado y la PD. Por último, se observó el cambio de una reabsorción de NaCI no electrogénica a una entrada electrogénica de Na+ sensible al amiloride

Asunto(s)

Ratas , Animales , Masculino , Ciego/fisiología , Potasio/administración & dosificación , Equilibrio Hidroelectrolítico , Permeabilidad de la Membrana Celular , Ratas Wistar , Agua/metabolismo

RESUMEN

The transepithelial net water movement (Jw) was minute by minute recorded in the cecum of Wistar rats adapted to a high potassium diet (HKD). The potential difference (PD), short circuit current (SCC) and unidirectional 22Na, 36Cl, and 89Rb fluxes were also measured. The hydrostatic and osmotic permeabilities were not modified by potassium adaptation when a standard bicarbonate buffer was employed. Potassium adaptation implicated the development of a secretory, transport-associated Jw (Jwt), associated to an increase in transepithelial PD, SCC and net sodium transport. Contrary to the case of control rats, no net chloride transport was observed in HKD rats. The secretory Jwt compensated, in the presence of sodium, chloride and bicarbonate, an absorptive Jwt. Water secretion was coupled to net potassium secretion. Replacement of chloride by sulphate ions was paralleled by the development of a net absorptive Jw and by increases in the transepithelial Pd and hydrostatic permeability. Replacement of the bicarbonate buffer by a tris-hepes buffer made drop both the observed absorptive Jw and PD amiloride sensitive Na+ entry was observed.