Differential expression of α₁-adrenergic receptor subtypes in coronary microvascular endothelial cells in culture

It has been postulated that in blood vessels under α₁-related stimulation, the endothelial intracellular calcium concentration ([Ca²⁺]_i) increases, which is necessary to induce nitric oxide synthesis, is the result of an increase in vascular smooth muscle, which subsequently, flows into the endothelial cells through gap junctions and it is not the result of a direct adrenergic stimulation of endothelial receptors. Others, however, postulate that endothelial α_1D-adrenoceptors, have a direct effect on nitric oxide synthesis. In order to clarify this phenomena, in this work we analyzed the presence of α₁receptor subtypes and their functional association with nitric oxide synthesis in rat coronary microvascular endothelial cells in culture, with pharmacological, immunological and reverse transcriptase polymerase chain reaction approaches. Our results show the presence and functional coupling with nitric oxide synthesis of α_1A and α_1D-adrenoceptor subtypes. α_1B-adrenoceptor subtype is not coupled with nitric oxide production.