Effects of calcium channel activators on the response of rabbit aortic rings to alpha₁-receptor agonists: Evidence for two modes of action

The interaction between activators of the calcium channel and the α_i-radreno-ceptor has been studied in isolated rabbit aortic rings. The data obtained in these investigations are not consistent with the idea of a homogenous population of α_i-receptors which trigger contraction via a single pathway. Our results suggest that calcium channel activators reveal two modes of spasmogenic action for α_i-adrenoceptor agonists. Furthermore, we have shown that there may be multiple drug recognition sites on the α_i-receptor.