RESUMO
In acute experiments on anesthetized rats, acetylcholine (Ach) constricts hepatic venous vessels, causing blood mobilization from the liver, and dilates the sphincters of hepatic veins at the exit from this organ, contributing to the intensification of the outflow of blood deposited in the liver. Vasoconstrictor reactions of capacitive vessels of the liver to Ach are realized through M-cholinoreceptors on endotheliocytes with further involvement of messenger, possibly noradrenaline, which activates alpha-adrenoreceptors on smooth muscle cells (SMC) of capasitive vessels. Dilation of Hv sphincters is carried out due to Ach-induced release of messenger in the vessel wall, probably adrenaline, which in turn activates beta-adrenoreceptors on SMC of the Hv. It is possible, that in such reaction partially involved NO.
Assuntos
Acetilcolina/farmacologia , Veias Hepáticas/efeitos dos fármacos , Fígado/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Vasoconstrição/efeitos dos fármacos , Antagonistas Adrenérgicos/farmacologia , Animais , Atenolol/farmacologia , Pressão Sanguínea/efeitos dos fármacos , Dioxanos/farmacologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Veias Hepáticas/metabolismo , Técnicas In Vitro , Fígado/irrigação sanguínea , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Fentolamina/farmacologia , Ratos , Receptores Adrenérgicos alfa/metabolismo , Receptores Adrenérgicos beta/metabolismo , Receptores Muscarínicos/metabolismo , Circulação Esplâncnica/efeitos dos fármacosRESUMO
In acute experiments on anesthetized rats was shown, that endothelin-1 constricts arterial and portal vessels of the liver, reduces blood flow in the liver, supresses tissue respiration and heat production in this organ. Thus, the level of oxygen pressure in the liver might grow. The influence endothelin-1 on tissue respiration and heat production is mediated through ET(A)-receptors.
