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Endothelin and nitric oxide release modulate aortic contraction to selected thrombin receptor agonists
H I Magazine1, O Butt, H R Yaghoutiel
1Department of Biology, Queens College, Flushing, New York 11367, USA.
The American Journal of Physiology
|June 1, 1996
Summary
Synthetic agonists TRAP-14 and TRAP-6 activate rat aorta smooth muscle. TRAP-14, but not TRAP-6, stimulates endothelin-1 release, influencing vascular contraction via endothelin-1 and nitric oxide pathways.
Area of Science:
- Vascular pharmacology
- Endothelin and nitric oxide signaling
Background:
- Alpha-thrombin receptor (PAR-1) agonists like TRAP peptides mediate vascular responses.
- Endothelin-1 (ET-1) and nitric oxide (NO) are key regulators of vascular tone.
Purpose of the Study:
- To investigate the roles of ET-1 and NO release in vascular contraction induced by TRAP-14 and TRAP-6.
- To compare the effects of TRAP-14 and TRAP-6 on ET-1 and NO pathways in rat aorta.
Main Methods:
- Isolated rat aortic rings were stimulated with TRAP-14 and TRAP-6.
- Vascular contraction was measured.
- ET-1 levels in perfusate were quantified.
- Effects of ET receptor antagonist (BQ-123) and NO synthase inhibitor (L-NNA) were assessed.
Main Results:
- TRAP-6 induced greater contraction than TRAP-14.
- TRAP-14, but not TRAP-6, increased ET-1 levels.
- Endothelial cells were not required for TRAP-14-induced ET-1 release.
- TRAP-14 potency was modulated by ET-1 and NO pathways, while TRAP-6 potency was not.
Conclusions:
- TRAP-14's vascular effects are modulated by ET-1 and NO, unlike TRAP-6.
- Thrombin receptor activation alone is insufficient to induce ET-1 and NO release in rat aorta.
- TRAP-6 exhibits limited function compared to TRAP-14 in this context.