RESUMO
Opioid mechanisms are involved in the control of water and NaCl intake and opioid receptors are present in the lateral parabrachial nucleus (LPBN), a site of important inhibitory mechanisms related to the control of sodium appetite. Therefore, in the present study we investigated the effects of opioid receptor activation in the LPBN on 0.3 M NaCl and water intake in rats. Male Holtzman rats with stainless steel cannulas implanted bilaterally in the LPBN were used. In normohydrated and satiated rats, bilateral injections of the opioid receptor agonist beta-endorphin (2 nmol/0.2 microl) into the LPBN induced 0.3 M NaCl (17.8+/-5.9 vs. saline: 0.9+/-0.5 ml/240 min) and water intake (11.4+/-3.0 vs. saline: 1.0+/-0.4 ml/240 min) in a two-bottle test. Bilateral injections of the opioid antagonist naloxone (100 nmol/0.2 microl) into the LPBN abolished sodium and water intake induced by beta-endorphin into the LPBN and also reduced 0.3 M NaCl intake (12.8+/-1.5 vs. vehicle: 22.4+/-3.1 ml/180 min) induced by 24 h of sodium depletion (produced by the treatment with the diuretic furosemide s.c.+sodium deficient food for 24 h). Bilateral injections of beta-endorphin into the LPBN in satiated rats produced no effect on water or 2% sucrose intake when water alone or simultaneously with 2% sucrose was offered to the animals. The results show that opioid receptor activation in the LPBN induces hypertonic sodium intake in satiated and normohydrated rats, an effect not due to general ingestive behavior facilitation. In addition, sodium depletion induced 0.3 M NaCl intake also partially depends on opioid receptor activation in the LPBN. The results suggest that deactivation of inhibitory mechanisms by opioid receptor activation in the LPBN releases sodium intake if excitatory signals were activated (sodium depletion) or not.
Assuntos
Ponte/efeitos dos fármacos , Ponte/fisiologia , Receptores Opioides delta/metabolismo , Receptores Opioides mu/metabolismo , Cloreto de Sódio/farmacocinética , beta-Endorfina/farmacologia , Animais , Ingestão de Líquidos/efeitos dos fármacos , Ingestão de Líquidos/fisiologia , Interações Medicamentosas , Ala(2)-MePhe(4)-Gly(5)-Encefalina/farmacologia , Masculino , Microinjeções , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Ratos , Ratos Sprague-Dawley , Receptores Opioides delta/antagonistas & inibidores , Receptores Opioides mu/antagonistas & inibidores , Resposta de Saciedade/efeitos dos fármacos , Resposta de Saciedade/fisiologia , Sacarose/farmacologia , Água/metabolismo , beta-Endorfina/metabolismoRESUMO
Viscosity and elasticity are the fundamental rheologic properties of respiratory mucus, and are important determinants of transportability of mucus in the mucociliary system. One technique that permits to monitor indirectly the rheologic properties of any sample is the photoacoustic technique. Using that technique, the absorption of isotonic saline solution by human mucus was monitored. The mucus was obtained from 11 volunteers, divided into two groups: five volunteers presenting pneumology symptoms (group I) and six healthy volunteers (group II). The photoacoustic signal of the mucus absorbing the saline solution was monitored as function of time, with measurements being performed each 10 min, up to 120 min. The resulting curves were fitted to sigmoidal curves to simulate the evolution on time of the photoacoustic signal. A characteristic time for the half saturation of the absorption process was obtained. For group I the time obtained was 23.3+/-5.3 min and for group II the time obtained was 55.0+/-7.7 min, both means being significantly different (Student t-test, p<0.05). This result supports the empirical practice of treating individuals presenting symptoms of airway obstruction with about 30 min of inhalations of isotonic saline solution vapor for the clearance of the airways.
Assuntos
Absorção/fisiologia , Muco/metabolismo , Cloreto de Sódio/farmacocinética , Adulto , Elasticidade , Transferência de Energia , Feminino , Humanos , Soluções Isotônicas/farmacocinética , Masculino , Mucosa Nasal/fisiologia , Fotoquímica/métodos , ViscosidadeRESUMO
A recently discovered family of protein kinases is responsible for an autosomal-dominant disease known as Gordon's syndrome or pseudohypoaldosteronism type II (PHA-II) that features hyperkalemia and hyperchloremic metabolic acidosis, accompanied by hypertension and hypercalciuria. Four genes have been described in this kinase family, which has been named WNK, due to the absence of a key lysine in kinase subdomain II (with no K kinases). Two of these genes, WNK1 and WNK4 located in human chromosomes 12 and 17, respectively, are responsible for PHA-II. Immunohystochemical analysis revealed that WNK1 and WNK4 are predominantly expressed in the distal convoluted tubule and collecting duct. The physiological studies have shown that WNK4 downregulates the activity of ion transport pathways expressed in these nephron segments, such as the apical thiazide-sensitive Na+-Cl- cotransporter and apical secretory K+ channel ROMK, as well as upregulates paracellular chloride transport and phosphorylation of tight junction proteins such as claudins. In addition, WNK4 downregulates other Cl- influx pathways such as the basolateral Na+-K+-2Cl- cotransporter and Cl-/HCO3- exchanger. WNK4 mutations behave as a loss of function for the Na+-Cl- cotransporter and a gain of function when it comes to ROMK and claudins. These dual effects of WNK4 mutations fit with proposed mechanisms for developing electrolyte abnormalities and hypertension in PHA-II and point to WNK4 as a multifunctional regulator of diverse ion transporters.
Assuntos
Hipertensão/fisiopatologia , Túbulos Renais/fisiologia , Potássio/farmacocinética , Proteínas Serina-Treonina Quinases/farmacologia , Cloreto de Sódio/farmacocinética , Regulação para Baixo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Transporte de Íons/fisiologia , Antígenos de Histocompatibilidade Menor , Mutação , Proteínas Serina-Treonina Quinases/genética , Proteína Quinase 1 Deficiente de Lisina WNKRESUMO
Split lamellae of posterior gills of Chasmagnathus granulatus adapted to 2.5 per thousand salinity were mounted in a modified Ussing chamber. With NaCl-saline on both sides of the preparation a transepithelial voltage (V(te)) of 4.1+/-0.5 mV (outside positive) was measured. After voltage-clamping, the negative short-circuit current (I(sc)) amounted to -142+/-21 micro A cm(-2) at a conductance (G(te)) of 44+/-5 mS cm(-2). Substitution of either chloride (by nitrate) or sodium (by choline) on both sides of split gill lamellae significantly reduced I(sc) (by 70-80%) and G(te) (by 30-50%). External CsCl (but not BaCl(2) or furosemide) inhibited the negative I(sc) without affecting G(te). Addition of ouabain, BaCl(2) or diphenylamine-2-carboxylate to the internal bath inhibited I(sc) at unchanged G(te). Internal acetazolamide did not affect I(sc) or G(te) across split gill lamellae. Unidirectional Na(+) influx across isolated and perfused posterior gills, however, was reduced by internal acetazolamide by approximately 20% at constant V(te). The results suggest that posterior gills of hyperosmoregulating C. granulatus display a high conductance epithelium that actively absorbs NaCl in a coupled way by an electrogenic mechanism similar to that seen in the thick ascending limb of Henle's loop and, to a minor degree, by an electroneutral mechanism, presumably via apical Na(+)/H(+)- and Cl(-)/HCO(3)(-)-antiports.
Assuntos
Braquiúros/metabolismo , Brânquias/metabolismo , Cloreto de Sódio/farmacocinética , Equilíbrio Hidroeletrolítico/fisiologia , Absorção , Acetazolamida/farmacologia , Animais , Transporte Biológico Ativo , Braquiúros/fisiologia , Eletrofisiologia , Brânquias/fisiologia , Transporte de Íons , Ouabaína/farmacologia , ortoaminobenzoatos/farmacologiaRESUMO
Ethidium bromide (EB) causes local astrocytic disappearance, with glia limitans disruption and supposed blood-brain barrier (BBB) breakdown The aim of this study was to investigate the BBB integrity after the injection of 0.1% EB (group E) or 0.9% saline solution (group C) into cisterna pontis of Wistar rats. Brainstem fragments were collected from 24 hours to 31 days post-injection for ultrastructural study and GFAP immuno-histochemical staining. Some animals received colloidal carbon ink by intravenous route at the same periods. In rats from group C, there was no sign of astrocyte loss and no leakage of ink from blood vessels in the injection site. In group E, astrocyte disappearance began at 48 hours and some areas were still devoid of astrocytic processes 31 days after. Leakage of carbon particles was seen from 48 hours to 7 days in the EB-induced lesions. Tight junctions did not show any detectable ultrastructural change due to the lack of perivascular astrocytes.
Assuntos
Astrócitos/patologia , Barreira Hematoencefálica/efeitos dos fármacos , Tronco Encefálico/patologia , Etídio/farmacocinética , Proteína Glial Fibrilar Ácida/química , Cloreto de Sódio/farmacocinética , Animais , Astrócitos/efeitos dos fármacos , Tronco Encefálico/efeitos dos fármacos , Modelos Animais de Doenças , Imuno-Histoquímica , Injeções , Masculino , Antagonistas Nicotínicos , Ratos , Ratos WistarRESUMO
We have previously demonstrated that blood volume (BV) expansion decreases saline flow through the gastroduodenal (GD) segment in anesthetized rats (Xavier-Neto J, dos Santos AA & Rola FH (1990) Gut, 31: 1006-1010). The present study attempts to identify the site(s) of resistance and neural mechanisms involved in this phenomenon. Male Wistar rats (N = 97, 200-300 g) were surgically manipulated to create four gut circuits: GD, gastric, pyloric and duodenal. These circuits were perfused under barostatically controlled pressure (4 cmH2O). Steady-state changes in flow were taken to reflect modifications in circuit resistances during three periods of time: normovolemic control (20 min), expansion (10-15 min), and expanded (30 min). Perfusion flow rates did not change in normovolemic control animals over a period of 60 min. BV expansion (Ringer bicarbonate, 1 ml/min up to 5% body weight) significantly (P < 0.05) reduced perfusion flow in the GD (10.3 +/- 0.5 to 7.6 +/- 0.6 ml/min), pyloric (9.0 +/- 0.6 to 5.6 +/- 1.2 ml/min) and duodenal (10.8 +/- 0.4 to 9.0 +/- 0.6 ml/min) circuits, but not in the gastric circuit (11.9 +/- 0.4 to 10.4 +/- 0.6 ml/min). Prazosin (1 mg/kg) and yohimbine (3 mg/kg) prevented the expansion effect on the duodenal but not on the pyloric circuit. Bilateral cervical vagotomy prevented the expansion effect on the pylorus during the expansion but not during the expanded period and had no effect on the duodenum. Atropine (0.5 mg/kg), hexamethonium (10 mg/kg) and propranolol (2 mg/kg) were ineffective on both circuits. These results indicate that 1) BV expansion increases the GD resistance to liquid flow, 2) pylorus and duodenum are important sites of resistance, and, 3) yohimbine and prazosin prevented the increase in duodenal resistance and vagotomy prevented it partially in the pylorus.
Assuntos
Volume Sanguíneo , Duodeno/inervação , Duodeno/fisiologia , Cloreto de Sódio/farmacocinética , Animais , Masculino , Substitutos do Plasma , Ratos , Ratos WistarRESUMO
The aim of this study was to analyze in vitro the dentinal diffusion of hydroxyl ions of calcium hydroxide pastes, prepared with different acid-base vehicles, in an inert nitrogen atmosphere. Sixty maxillary incisors with mature apexes were selected and after access and root canal preparation each root was filled with calcium hydroxide pastes prepared with different vehicles: saline solution, anesthetic and polyethylene glycol 400. The roots were then sectioned 2 mm from the apical vertex and the teeth mounted in the center of a round platform, filled with saline solution up to 2 mm from the root tip. The platforms remained inert in an atmosphere of nitrogen, completely sealed, in the absence of light and with a constant temperature of 36.5 degrees C. Diffusion analysis of the hydroxyl ions was carried out by a colorimetric method on days 7, 15, 30, 45 and 60. Calcium hydroxide pastes prepared with saline solution and anesthetic showed a pH change of 5-7 to 7-8 after 30 days, remaining at this level at 60 days. In the polyethylene glycol 400 group, the same alteration occurred at 45 days, and continued at 60 days.
Assuntos
Hidróxido de Cálcio/farmacocinética , Permeabilidade da Dentina , Irrigantes do Canal Radicular/farmacocinética , Dentina/metabolismo , Difusão , Humanos , Concentração de Íons de Hidrogênio , Radical Hidroxila/química , Lidocaína/farmacocinética , Veículos Farmacêuticos , Polietilenoglicóis/farmacocinética , Cloreto de Sódio/farmacocinética , Soluções/química , Solventes/química , Estatísticas não Paramétricas , Raiz Dentária/metabolismoAssuntos
Cloretos/farmacocinética , Túbulos Renais Coletores/metabolismo , Sódio/farmacocinética , Animais , Fator Natriurético Atrial/fisiologia , Transporte Biológico Ativo/fisiologia , Dinoprostona/fisiologia , Diuréticos/farmacologia , Fator de Crescimento Epidérmico/fisiologia , Humanos , Cloreto de Sódio/farmacocinética , Vasopressinas/fisiologia , Equilíbrio Hidroeletrolítico/fisiologiaRESUMO
Parameters of renal function were studied in conscious and anesthetized one-kidney (1K) and one-kidney/one-clip (1K-1C) rats. Effective renal blood flow (ERBF) was significantly lower in anesthetized 1K-1C rats than in conscious ones (12.1 +/- 1.6 vs. 16.4 +/- 1.2 ml/min). Renal function was evaluated in two-kidney (2K), 1K and 1K-1C unanesthetized rats. ERBF was lower in 1K and 1K-1C animals than in 2K rats. Glomerular filtration rate (GFR) and urinary sodium excretion (UNa.V) were not affected by uninephrectomy with or without clipping the renal artery. In 1K-1C rats, mean arterial pressure (MAP) increased from 100 +/- 2 to 140 +/- 1 mm Hg. Subsequently, the renal ability of unanesthetized rats to handle Na was studied by a sustained extracellular fluid volume expansion (EFVE) in all groups. During EFVE, MAP remained unchanged in the 2K and 1K groups and decreased significantly in the 1K-1C group, ERBF did not change and GFR increased to the same extent in all groups. The increase in UNa.V was 40% higher in 2K than in 1K or 1K-1C rats. These findings indicate that the relatively smaller natriuretic response to a saline load of 1K rats with or without a clip in the renal artery, as compared with 2K rats, could be ascribed to renal mass reduction. Finally, the study shows the advantage of performing studies of renal function in hypertension in conscious rather than anesthetized rats.
Assuntos
Hipertensão Renovascular/metabolismo , Rim/metabolismo , Natriurese/fisiologia , Cloreto de Sódio/farmacocinética , Anestesia , Animais , Pressão Sanguínea/efeitos dos fármacos , Espaço Extracelular/metabolismo , Taxa de Filtração Glomerular/efeitos dos fármacos , Hematócrito , Masculino , Nefrectomia , Ratos , Ratos Endogâmicos , Circulação Renal/efeitos dos fármacos , Cloreto de Sódio/urinaRESUMO
Osmotic stimulation of the skin of the toad Bufo arenarum with isotonic (115 mM) or hypertonic (400 mM) NaCl solutions produced a marked and reversible antidiuresis within 5 min. No changes in plasma osmolarity were detected in the course of this response. Hypophysectomized animals exhibited a lower and delayed antidiuresis when exposed to a hypertonic environment (400 mM NaCl). This antidiuretic response was drastically reduced in normal toads after ten consecutive days of administration of the sympatoplexic guanethidine. The existence of a feed-forward control of urine production initiated by cutaneous osmotic sensors and involving an adrenergic component is proposed.
Assuntos
Diurese , Fenômenos Fisiológicos da Pele , Animais , Bufo arenarum , Hipofisectomia , Masculino , Osmose , Pele/metabolismo , Cloreto de Sódio/farmacocinética , Urina/fisiologiaRESUMO
Experience with a relatively new but safe and simple method for termination of early pregnancy is described. Opinions regarding its mode of action are also discussed (AU)