Angiotensin effects on vas deferens adrenergic and purinergic neurotransmission

Angiotensin effects on purinergic and adrenergic neurotransmission in the rabbit vas deferens were examined. Both angiotensins inhibited the non-adrenergic, and potentiated the adrenergic, neurogenic contraction. Angiotensin III inhibited the non-adrenergic neurogenic contraction to a greater extent than angiotensin II at all concentrations tested (maximal inhibition being 42 +/- 4 vs. 17 +/- 3% for angiotensin II). Angiotensin II was more potent than angiotensin III at potentiating adrenergic neurotransmission. Neither peptide altered the postjunctional action of either putative neurotransmitter, ATP or norepinephrine. These results are inconsistent with the hypothesis that ATP and norepinephrine are released in constant ratios. Furthermore, the different pattern of angiotensin responses is consistent with the existence of at least two separate angiotensin receptors with markedly different affinities for angiotensin II and angiotensin III.