Characterization of endothelin receptors in isolated, perfused human spleen.

At present, there is no information on endothelin-1 (ET-1)-mediated vascular effects in the human spleen. The objectives of this study were to investigate the in vitro vascular responses to ET-1 using pharmacologic probes (selective ET receptor agonists/antagonists) and to characterize the ET receptor population in the human spleen. Spleens (n = 6) were removed from patients for treatment of underlying disease.

Ethanol reduces the endothelin-B receptor-mediated increase in portal inflow resistance in the isolated, perfused canine liver.

Ethanol can affect the regulation of liver hemodynamics through the release of vasoactive mediators such as nitric oxide and endothelins (ETs). The purpose of this study was to investigate the effects of ethanol on the changes in arterial and portal perfusion pressure induced by ET receptor activation. Ethanol significantly reduced portal, but not arterial perfusion pressure.

Involvement of nitric oxide in the smooth muscle tone of the isolated canine spleen and the responses to acetylcholine and substance P.

1. The canine isolated spleen was perfused at constant flow with warmed (37 degrees C) Krebs solution while the splenic arterial perfusion pressure (SAPP) and spleen weight were recorded continuously. An augmented smooth muscle tone was maintained by a continuous intra-arterial infusion of noradrenaline (0.

Characterisation of functional endothelin receptors in the canine isolated perfused spleen.

The endothelin receptor subtypes involved in the vasoconstriction, capsular smooth muscle contraction, prostaglandin E2 and prostacyclin release induced by endothelin-1 have been investigated in the canine isolated perfused spleen using both the endothelin ETA receptor antagonist FR 139317 and the endothelin ETB receptor agonist IRL 1620. THe isolated canine spleen was perfused with warmed (37 degrees C) and oxygenated (95% O2/5% CO2) Krebs solution at constant flow with continuous recording of splenic arterial perfusion pressure and spleen weight. Samples of splenic venous effluent were collected to determine the amounts of prostaglandin E2 and prostacyclin, measured by radioimmunoassay.

Role of endothelin ETA and ETB receptors in the arterial vasculature of the isolated canine liver.

The vascular effects of endothelin-1 (ET-1; ETA/ETB agonist), sarafotoxin 6b (S6b; ETA agonist), and IRL 1620 (ETB agonist) were investigated in the isolated canine liver arterial circuit before and after infusions of indomethacin (cyclo-oxygenase inhibitor) and N omega L-nitro arginine methyl ester (L-NAME; nitric oxide synthesis inhibitor). Norepinephrine (NE) was used as vasconstrictor control agent. The portal vein, hepatic artery, and vena cava were cannulated in vitro and the liver was perfused via the hepatic artery and portal vein with oxygenated (95%) O2/5% CO2) Krebs solution at 37 degrees C.