Characteristics of relaxation induced by calcitonin gene-related peptide in contracted rabbit basilar artery.

✓ Increasing evidence suggests that disturbances in the modulatory influence of the vasoactive peptide, calcitonin gene—related peptide (CGRP), contribute to the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). However, only limited success has been achieved in trials attempting to ameliorate vasospasm by modifying CGRP function. To better understand the potential utility of targeting CGRP-mediated relaxation, it is important both to identify the interactions CGRP may have with other elements of the vasospastic response and to characterize the mechanisms through which CGRP elicits vasodilative effects. The present studies examined the effects of CGRP on vascular responsiveness using tension measurements of ring strips of rabbit basilar artery maintained in vitro. Pretreatment of vessels with CGRP (100 nM) inhibited vasoconstrictor responses to the potent protein kinase C (PKC) activator, phorbol 12,13-dibutyrate (PDB). This particular contractile response was selected because PKC-me...