Calcitonin gene-related peptide relaxed rat tail artery helical strips in vitro in an intracellular calcium-dependent manner

The vasoactive properties of calcitonin gene-related peptide (CGRP) were examined using the helical strip of the rat tail artery as a model. CGRP was found to inhibit norepinephrine-induced contraction but not KCl- or vasopressin-induced contraction. No significant inhibition occurred in either KCl- or norepinephrine-stimulated strips when Ca²⁺ was added incrementally to otherwise Ca²⁺-free bathing solution. However, a dose-related inhibition to norepinephrine-stimulated contraction in Ca²⁺-free bathing solution was observed. This strongly suggests that CGRP exerts its effect by inhibiting the mobilization of intracellular Ca²⁺.