Selective activation of cardiovascular adenylate cyclase in vivo

Cyclic AMP levels were measured in cardiac and vascular tissues removed from pentobarbitone-anesthetized rats pretreated with theophylline 45 mg/kg i.p. Noradrenaline, 20 microng/kg i.v., increased cardiac but not vascular cyclic AMP levels; this selective effect of noradrenaline was not altered by pretreatment with phenoxybenzamine, 1 mg/kg i.v. Tazolol, 120 microng/kg i.v., selectively increased cardiac cyclic AMP levels whereas fenoterol, 15 microng/kg i.v., selectively increased vascular cyclic AMP levels. The results suggest that adenylate cyclase activation in cardiac and vascular tissued in vivo is mediated by beta adrenoceptors which consist of different subtypes.