Selective modulation of noradrenaline release by α 2- adrenoceptor blockade in the rat-tail artery in vitro

Abstract

1. The effects of blocking α 2-adrenoceptors on noradrenaline (NA) and adenosine 5′-triphosphate (ATP) release from postganglionic sympathetic nerves have been investigated in rat-tail artery in vitro. Continuous amperometry was used to measure NA release and intracellularly recorded excitatory junction potentials (e.j.p.'s) were used to measure ATP release. 2. Application of the α 2-adrenoceptor antagonist, idazoxan (1 μM), increased the amplitude of NA-induced oxidation currents evoked by trains of 10 stimuli at 1 and 10 Hz. 3. In cells deep in the media, idazoxan (1 μM) had no effect on the amplitude of e.j.p.'s evoked by trains of 10 stimuli at 1 and 10 Hz. In cells close to the adventit..