ACTION OF CALCITONIN GENE-RELATED PEPTIDE UPON BOVINE VASCULAR ENDOTHELIAL AND SMOOTH-MUSCLE CELLS GROWN IN ISOLATION AND CO-CULTURE

Bovine aortic endothelial cells (BAE) and smooth muscle cells (BASM) were grown separately and in co-culture. Calcitonin gene-related peptide (CGRP) caused dose-dependent activation of adenylate cyclase in each cell type when grown in isolation. The concentration of CGRP causing half-maximal activation in BAE and BASM was 200 nM and 310 nM, respectively. In cells grown in co-culture exposure to produced dose-dependent elevations in cyclic GMP content which were maximal 1 min after application of the agonist. CGRP (1 nM-1 μM) did not stimulate a rise in cyclic GMP in co-cultures. Displaceable CGRP binding was identified throughout the wall of the bovine aorta. We conclude that CGRP receptors coupled to adenylate cyclase are present on BAE and BASM, but there is no coupling of these receptors to the release of any agent (such as endothelium-derived relaxing factor) that activates guanylate cyclase.