Beta-adrenoceptor subtype of the venous capacity system: characterization by venous occlusion plethysmography.

In order to characterize the beta-adrenoceptor subtype of the venous vessel wall, venous occlusion plethysmograph studies were carried out in 7 healthy volunteers. Venous distensibility (VD) was considered to be a measure of venous tone. Infusion of the beta 1- and beta 2-adrenoceptor agonist isoproterenol (I), of the predominantly beta 2-adrenoceptor agonist fenoterol (F) and of the predominantly beta 1-adrenoceptor agonist dobutamine (D) in increasing doses led to a significant increase in VD by I and F but not by D. Administration of the beta 1-adrenoceptor antagonists betaxolol (B) and metoprolol (M) did not significantly change VD. Neither beta-adrenoceptor antagonist prevented the increase in VD provoked by subsequent administration of I or F. It is concluded that beta-adrenoceptors in the venous vessel wall belong to the beta 2-adrenoceptor subtype.