Reactivity of isolated bovine mesenteric and hepatic veins to vasoactive agents and specific antigen.

In an attempt to investigate the possible contribution of the mesenteric and hepatic vasculature to the haemodynamic changes occurring during bovine systemic anaphylaxis, the pharmacological reactivity of isolated bovine mesenteric and hepatic veins was studied. Both mesenteric and hepatic veins contracted in the presence of histamine, 5-hydroxytryptamine (5HT), acetylcholine, dopamine and noradrenaline, and relaxed in the presence of isoprenaline. The mesenteric veins contracted in the presence of concentrations of isoprenaline greater than 1 mug/ml. By the use of antagonists, the receptor populations of bovine mesenteric and hepatic veins were shown to be similar to those of many other vascular preparations. Hepatic veins isolated from calves previously sensitised to horse serum contracted forcefully in the presence of horse plasma (the Schultz-Dale phenomenon), whereas mesenteric veins isolated from the same animals did not. Hepatic veins may be implicated in the haemodynamics of bovine systemic anaphylaxis.