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.
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.