HUMAN ALPHA-CALCITONIN GENE-RELATED PEPTIDE (CGRP)-(8-37), BUT NOT (CGRP)-(28-37), INHIBITS CAROTID VASODILATOR EFFECTS OF HUMAN ALPHA-CGRP INVIVO

Human alpha-calcitonin gene-related peptide-(8-37) alone (up to doses of 30 nmol kg-1 min-1) had no significant effects on blood pressure, heart rate or common or internal carotid haemodynamics, although it caused significant, reversible, inhibition of the hypotensive, tachycardic, and common and internal carotid vasodilator effects of human alpha-CGRP (0.03 nmol kg-1 min-1) in conscious, Long Evans rats. Human alpha-CGRP-(28-37) up to doses of 300 nmol kg-1 min-1 had no cardiovascular effects itself and did not influence responses to human alpha-CGRP. These results are consistent with the carotid haemodynamic effects of human alpha-CGRP being due largely to activation of the CGRP1-receptor subtype.