Role of alpha‐adrenoceptors in constrictor responses of rat, guinea‐pig and rabbit small arteries to neural activation.

Abstract

1. We have investigated the adrenoceptors mediating the force and electrical responses of rat mesenteric small arteries (i.d. 100‐300 microns). Some mechanical experiments were also performed using guinea‐pig and rabbit mesenteric small arteries. 2. Vessels were mounted on an isometric myograph and stimulated either with short (3 s) trains of electric field stimuli (ca. 0.2 ms pulse width) at 25 Hz (nerve stimulation) or with 10 microM‐exogenous noradrenaline. 3. Nerve stimulation caused a force response equal to ca. 40% of the response to exogenous noradrenaline and, in the rat vessels, excitatory junction potentials (EJPs), which normally summated to give a depolarization of ca. 10 mV (alt..