Adrenomedullin and CGRP receptors mediate different effects in the rat adrenal cortex

Adrenomedullin (AM) exerts its effects through two distinct receptor subtypes: the AM receptor, and the CGRPI receptor. In most tissues activation of these subtypes brings about similar effects, with only the magnitude of the effect varying. In the rat adrenal cortex, however, this does not appear to be the case. Both CGRPI and AM receptors are present in the rat adrenal cortex. Incubation of zona glomerulosa cells with AM caused an increase in aldosterone secretion, but AM had no effect on angiotensin II-stimulated aldosterone secretion. The action of AM was not affected by CGRP8-37, the CGRP receptor antagonist, suggesting that its effect was mediated by the adrenomedullin receptor. CGRP on the other hand, did not significantly affect basal aldosterone although it attenuated the response to angiotensin II. These data suggest that the CGRP receptor and the AM receptor mediate different effects in the rat adrenal zona glomerulosa.