Dopamine induces intracellular Ca2+ signals mediated by alpha(1B)-adrenoceptors in rat pineal cells

Abstract

We have studied the functional interaction of dopamine with a -adrenoceptor subtypes by measuring intracellular Ca2q 1 levels in pineal cells, a cell type where adrenoceptors are well characterized. We show that dopamine induces transient intracellular Ca2q signals in only 70% of cells responding to phenylephrine. Dopamine-induced Ca2q signals desensitise faster than Ca2q transients elicited with phenylephrine and are selectively blocked by desipramine, imipramine, and a -adrenoceptor antagonists. These results suggest that 1B dopamine induced Ca2q signals are mainly due to the activation of one subtype of a-adrenoceptor, the a .