Effects of A1-adenosine receptor antagonists on purinergic transmission in the guinea-pig vas deferens in vitro

Abstract

1. Intracellularly recorded excitatory junction potentials (e.j.ps) were used to study the effects of adenosine receptor antagonists on neurotransmitter release from postganglionic sympathetic nerve terminals in the guinea-pig vas deferens in vitro. 2. The A1 adenosine receptor antagonists, 8-phenyltheophylline (10 μM) and 8-cyclopentyl-1,3-dipropylxanthine (0.1 μM), increased the amplitude of e.j.ps evoked during trains of 20 stimuli at 1 Hz in the presence, but not in the absence, of the α2-adrenoceptor antagonist, yohimbine (1 μM) or the non-selective α-adrenoceptor antagonist, phentolamine (1 μM). 3. Adenosine (100 μM) reduced the amplitude of e.j.ps, both in the presence and in the abse..