Effects of adrenomedullin on rat cerebral arterioles.

The effects of adrenomedullin on isolated rat intracerebral arterioles were investigated and compared with those of calcitonin gene-related peptide (CGRP) and amylin. Adrenomedullin produced dose-dependent vasodilation (maximum dilation 27.1 +/- 2.1% at 3 x 10(-7) M, median effective dose (EC50)) 1.6 x 10(-9) M). CGRP produced similar vasodilation (19.8 +/- 4.1%) at 10(-7) M with a lower EC50 of 2.8 x 10(-11) M. Amylin did not cause vasodilation at concentrations up to 10(-6) M. Adrenomedullin-induced vasodilation was significantly suppressed by CGRP-(8-37). These data suggest that adrenomedullin is a potent vasodilator for arterioles in the cerebral microcirculation that acts through CGRP receptors.