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 postjuctional 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.
Bibliographical noteFunding Information:
The expert technical assistance of E. Stein and R. Marzsa-lek is greatly appreciated, as is the manuscript preparation by S. Kurki. This work was supported by Public Health Services Grant No. R01 HL 34600 from NHLBI.
- Adenosine triphosphate
- Adrenergic neurotransmission
- Angiotensin II
- Angiotensin III
- Purinergic neurotransmission