Endogenous calcitonin gene-related peptide suppresses vasoconstriction mediated by adrenergic nerves in rat mesenteric resistance blood vessels

The role of perivascular calcitonin gene-related peptide (CGRP)-containing nerves in the modulation of adrenergic nerve-mediated vasoconstrictions was studied in the rat perfused mesenteric vascular bed. A frequency-dependent vasoconstriction induced by periarterial nerve stimulation (1-6 Hz) of the bed was significantly potentiated by perfusion of 1 mu M CGRP-(8-37) (CGRP receptor antagonist) or to a similar extent after treatment with 500 nM ca psaicin. In the preparations treated with capsaicin, CGRP-(8-37) caused a s mall potentiation of periarterial nerve stimulation-induced vasoconstrictio n. Exogenous CGRP (0.1-1 nM) concentration-dependently attenuated the augme nted vasoconstriction in response to periarterial nerve stimulation after t reatment with capsaicin. However, exogenous CGRP-(1 nM) did not attenuate t he periarterial nerve stimulation-induced vasoconstriction in the bed untre ated with capsaicin. These results suggest that endogenous CGRP, which is r eleased from CGRP-containing nerves, suppresses the adrenergic nerve functi on involved in mechanisms regulating the tone of resistant blood vessels. ( C) 1999 Elsevier Science B.V. All rights reserved.