Abstract
Calcitonin gene-related peptide (CGRP) is a recently discovered amino peptide that induces vasodilation, hypotension, and tachycardia. Tachycardia elicited by CGRP may be partly due to sympathetic stimulation in the alert state. However, the endocrrne effects of CGRP during halothane anesthesia still remain to be elucidated. Endocrine effects of two doses of CGRP (4 μg ⋅ kg-1 and 40 μg ⋅ kg-1) on plasma levels of catecholamines and aldosterone and plasma renin activity (PRA), were measured in halothane-anesthetized dogs. With 40 μg ⋅ kg-1 of CGRP, norepinephrine and epinephrine concentrations significantly increased during the infusion period, but no significant changes in catecholamines occurred at 4μg ⋅ kg-1 of CGRP throughout observation. PRA significantly increased at doses of 4 and 40μg ⋅ kg-1 of CGRP during the infusion period. With 40 μg ⋅ kg-1 of CGRP, aldosterone increased significantly throughout observation. In contrast, there were no significant changes in plasma aldosterone during and after the infusion with 4 μg ⋅ kg-1 of CGRP. The two doses of CGRP used produced no consistent changes in aldosterone despite significant increases in PRA. The results of the present study suggest that CGRP may be an endocrine modulator. In addition, halothane anesthesia may partially suppress activation of the sympathetic nervous system and of the renin-angiotensin-aldosterone system caused by infusion of CGRP.
