[Characteristics of alpha adrenoceptors of lymphatics and their physiological significance].
We studied isolated bovine mesenteric lymphatics to investigate the pharmacological properties of the postjunctional-adrenoceptors. Rings of the lymph vessels were mounted for isometric tension recording in organ chambers filled with Krebs-Ringer bicarbonate solution. The lymph vessels contracted when exposed to phenylephrine and clonidine. The relative sensitivity of the vessels to clonidine was larger than to phenylephrine. Yohimbine was a competitive antagonist against phenylephrine and clonidine in the lymph vessels. Prazosin caused a parallel shift to the right of the dose-response curve to phenylephrine, and not to clonidine in the vessels. The Schild's plot for yohimbine in the lymph vessels suggests that the presence of both alpha 1- and alpha 2-like adrenoceptors on lymphatic smooth muscle cells.
D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D003000:Clonidine / Q000494:pharmacology; D066298:In Vitro Techniques; D008208:Lymphatic System / Q000502:physiology*; D008643:Mesentery; D009119:Muscle Contraction / Q000187:drug effects; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D015016:Yohimbine / Q000494:pharmacology
D011942:Receptors, Adrenergic, alpha; D010656:Phenylephrine; D015016:Yohimbine; D003000:Clonidine; D011224:Prazosin