Olvanil: more potent than capsaicin at stimulating the efferent function of sensory nerves.

The capsaicin analogue olvanil stimulated an increase in cutaneous blood flow when injected intradermally into the anaesthetised rabbit, as measured using a 133Xenon clearance method. Olvanil was found to be a 10-fold more potent vasodilator (on a molar basis) than capsaicin. The effect of both vasodilators was significantly inhibited by the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP-(8-37). These findings suggest that olvanil stimulates the efferent function of cutaneous sensory nerves in a more potent manner than capsaicin. We therefore suggest that olvanil is a useful pharmacological tool for studying the activity of neuropeptides released from sensory nerves.