AIMS: Glyceryl trinitrate (GTN) is the most commonly used anti-anginal agent, yet its mechanism of action has still to be fully established. Release of nitric oxide (NO) and the selectivity of GTN in the venous system are believed to be crucial to this drug's anti-anginal action.
METHODS: Rat superior mesenteric arteries and renal veins were mounted in a wire myograph with an intraluminal NO microsensor.
RESULTS: In the superior mesenteric arteries, GTN (1 nM to 10 microM) produced a dose-dependent vasodilatation without NO release, except at concentrations supramaximal for relaxation. GTN was found to be markedly less potent in a wide range of veins tested, and lowering the oxygen concentrations in the myograph to that of the venous system did not improve the venodilator activity of GTN.
CONCLUSION: This is the first time that NO release from GTN has been monitored electrochemically in real time, simultaneously with vasodilatation. Unlike the endothelium-dependent vasodilator carbachol, NO could only be measured at concentrations of GTN that are supramaximal for relaxation. GTN was found to be arterioselective in vitro, even when oxygen levels were lowered to mimic those of the venous system in vivo.
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid
- Dose-Response Relationship, Drug
- In Vitro Techniques
- Mesenteric Artery, Superior
- Nitric Oxide
- Rats, Sprague-Dawley
- Renal Veins
- Time Factors
- Vasoconstrictor Agents
- Vasodilator Agents