RESUMO
The making and sealing of a tight junction (TJ) requires cell-cell contacts and Ca2+, and can be gauged through the development of transepithelial electrical resistance (TER) and the accumulation of ZO-1 peptide at the cell borders. We observe that pertussis toxin increases TER, while AIF3 and carbamil choline (carbachol) inhibit it, and 5-guanylylimidodiphosphate (GTPTs) blocks the development of a cell border pattern of ZO-1, suggesting that G-proteins are involved. Phospholipase C (PLC) and protein kinase C (PKC) probably participate in these processes since (i) activation of PLC by thyrotropin-1 releasing hormone increases TER, and its inhibition by neomycin blocks the development of this resistance; (ii) 1,2-dioctanoylglycerol, an activator of PKC, stimulates TER development, while polymyxin B and 1-(5-isoquinoline sulfonyl)-2-methyl-piperazine dihydrochloride (H7), which inhibit this enzyme, abolish TER. Addition of 3-isobutyl-1-methyl-xanthine, dB-cAMP or forskolin do not enhance the value of TER, but have just the opposite effect. Trifluoperazine and calmidazoline inhibit TER development, suggesting that calmodulin (CaM) also plays a role in junction formation. These results indicate that junction formation may be controlled by a network of reactions where G-proteins, phospholipase C, adenylate cyclase, protein kinase C and CaM are involved.
Assuntos
Calmodulina/fisiologia , Proteínas de Ligação ao GTP/fisiologia , Junções Intercelulares/fisiologia , Proteína Quinase C/fisiologia , Fosfolipases Tipo C/fisiologia , 1-(5-Isoquinolinasulfonil)-2-Metilpiperazina , Toxina Adenilato Ciclase , Animais , Cálcio/fisiologia , Carbacol/farmacologia , Células Cultivadas , Condutividade Elétrica/efeitos dos fármacos , Condutividade Elétrica/fisiologia , Células Epiteliais , Epitélio/metabolismo , Epitélio/fisiologia , Junções Intercelulares/metabolismo , Isoquinolinas/farmacologia , Rim/citologia , Rim/metabolismo , Rim/fisiologia , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Neomicina/farmacologia , Toxina Pertussis , Piperazinas/farmacologia , Polimixina B/farmacologia , Proteína Quinase C/antagonistas & inibidores , Trifluoperazina/farmacologia , Fatores de Virulência de Bordetella/farmacologiaRESUMO
Denervation procedures that affect the sympathetic system of the kidney, as demonstrated by norepinephrine depletion of renal tissue, increased urine volume, fractional sodium excretion, and free water clearance in anesthetized water-loaded dogs. These increases were reduced by atropine, which also blocked the increase above those basal functional levels produced by acetylcholine in both innervated and denervated kidneys. An in vitro tubular cell preparation of innervated kidneys corresponding to the outer cortex showed [3H]quinuclidinyl benzilate (QNB) binding parameters characteristic of muscarinic receptors. Denervation did not change either [3H]QNB binding parameters or the ability of inner and outer cortex cells to perform the hemicholinium-3-inhibitable, sodium-dependent choline uptake and conversion of [3H]choline to [3H]acetylcholine. This cell membrane behavior is similar to that observed in tissues where cholinergic neuronal structures are present, suggesting the existence of a cholinergic innervation of the kidney, independent of the integrity of vessel-traveling nerves. Similarly, the finding of choline acetyltransferase in renal tissue, unaffected by sympathetic denervation, seems to confirm the presence of cholinergic nerve terminals. The cholinergic system may thus contribute to the regulation of tubular reabsorption of sodium and water in some conditions.
Assuntos
Rim/inervação , Sistema Nervoso Parassimpático/fisiologia , Acetilcolina/biossíntese , Acetilcolina/farmacologia , Animais , Atropina/farmacologia , Colina/metabolismo , Colina O-Acetiltransferase/metabolismo , Denervação , Cães , Rim/efeitos dos fármacos , Rim/metabolismo , Masculino , Muscarina/metabolismoRESUMO
The bilateral destruction of the ventral noradrenergic pathway induced by 6-hydroxydopamine (6-OHDA) administration into the ventral pons led to an increase in arterial blood pressure (ABP) and norepinephrine depletion in the amygdaloid complex, nucleus accumbens, septal area and olfactory bulb. Specific angiotensin converting enzyme (ACE) activity was significantly increased only in the amygdaloid complex (Control: 4.56 +/- 0.95; Vehicle: 4.08 +/- 1.07; 6-OHDA: 11.76 +/- 1.84). A significant correlation between arterial blood pressure and specific ACE activity levels in the amygdaloid complex was observed (r: 0.775; p less than 0.002). These results suggest that an increase in specific ACE activity of the amygdaloid complex after norepinephrine depletion could play a role in the development of hypertension in this model.
Assuntos
Tonsila do Cerebelo/metabolismo , Hipertensão/metabolismo , Peptidil Dipeptidase A/metabolismo , Animais , Hidroxidopaminas/toxicidade , Hipertensão/etiologia , Masculino , Vias Neurais/efeitos dos fármacos , Vias Neurais/metabolismo , Norepinefrina/metabolismo , Oxidopamina , Ponte/efeitos dos fármacos , Ponte/metabolismo , Ratos , Ratos EndogâmicosRESUMO
Superior cervical ganglionectomy (SCGx) of Wistar rats brought about a significant increase of plasma renin activity (PRA) 9 or 15 days later, an effect not observed 48 days after surgery. The same surgical procedure performed in Chbb Tom rats did not result in significant modification of PRA. In both strains of rats immobilization stress induced a 2.3-3.3-fold increase of PRA regardless of whether the animals had intact superior cervical ganglia. The injection of the angiotensin-converting enzyme inhibitor captopril to SCGx Wistar rats at the time of elevated PRA induced a severe hypotension, while it did not affect blood pressure in sham-operated animals. In both strains of rats SCGx resulted in depressed circulating aldosterone levels at all studied times after surgery.
Assuntos
Aldosterona/sangue , Renina/sangue , Simpatectomia , Animais , Pressão Sanguínea/efeitos dos fármacos , Captopril/farmacologia , Feminino , Imobilização , Ratos , Ratos Endogâmicos , Sistema Renina-Angiotensina , Estresse Fisiológico/sangue , Estresse Fisiológico/fisiopatologia , Equilíbrio HidroeletrolíticoRESUMO
Superior cervical ganglionectomy (SCGx) of Wistar rats brought about a significant increase of plasma renin activity (PRA) 9 or 15 days later, an effect not observed 48 days after surgery. The same surgical procedure performed in Chbb Tom rats did not result in significant modification of PRA. In both strains of rats immobilization stress induced a 2.3-3.3-fold increase of PRA regardless of whether the animals had intact superior cervical ganglia. The injection of the angiotensin-converting enzyme inhibitor captopril to SCGx Wistar rats at the time of elevated PRA induced a severe hypotension, while it did not affect blood pressure in sham-operated animals. In both strains of rats SCGx resulted in depressed circulating aldosterone levels at all studied times after surgery.