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Reprod Toxicol ; 65: 95-103, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27421582

RESUMO

We recently demonstrated that acetylcholine (ACh) produced reliable vasoconstrictions in the umbilical cords. This study investigated the possible mechanisms with different antagonists. ACh-mediated vasoconstrictions were decreased by voltage-operated calcium (Ca2+) channels antagonist nifedipine or inositol-1,4,5-trisphosphate-mediated Ca2+ release antagonist 2-aminoethyl diphenylborinate, indicating that both extracellular and intracellular calcium modulated the ACh-stimulated umbilical contraction. Intracellular Ca2+ concentrations were increased simultaneously with vasoconstrictions by ACh in the umbilical vessels. Inhibiting large-conductance calcium-dependent potassium (BK) channels enhanced ACh-mediated contraction, whereas inhibiting voltage dependent potassium (K+), inward rectifier K+ and ATP-sensitive K+ channels had no effects. Incubation with specific K+ channel inhibitors showed that ACh suppressed BK currents rather than 4-aminopyridine-sensitive K+ channels currents. The results suggested that blood vessels in umbilical cords had special characteristics in response to cholinergic signals. ACh-stimulated umbilical vasoconstrictions were mediated via muscarinic receptor subtype 1/3-protein kinase C/cyclooxygenase-BK channel pathways.


Assuntos
Acetilcolina/farmacologia , Canais de Cálcio/fisiologia , Agonistas Colinérgicos/farmacologia , Canais de Potássio/fisiologia , Cordão Umbilical/efeitos dos fármacos , Vasoconstrição/efeitos dos fármacos , Animais , Cálcio/fisiologia , Bloqueadores dos Canais de Cálcio/farmacologia , Artérias Carótidas/efeitos dos fármacos , Artérias Carótidas/fisiologia , Feminino , Técnicas In Vitro , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/fisiologia , Bloqueadores dos Canais de Potássio/farmacologia , Gravidez , Coelhos , Ratos Sprague-Dawley , Cordão Umbilical/fisiologia
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