Abstract
The in vitro effects of angiotensin II (Ang II) in human vessels are not well studied. The development of specific Ang II-receptor antagonists has made it possible to delineate more carefully the receptor mechanisms involved. The objective of this study was twofold: to investigate the effect of Ang II on human coronary arteries and to study the effects of angiotensin II type 1 receptor blockade with losartan. The setting was contractile experiments with ring segments of coronary arteries. We observed that Ang II is a vasoconstrictor of human coronary arteries, with a pEC50 value of 9.26 +/- 0.22 and Emax of 68.7 +/- 9.61% of potassium-induced contraction. Losartan (10-100 nM) shifted the concentration-response curve of Ang II to the right, with pEC50 values of 7.64 +/- 0.10 and 7.00 +/- 0.15, respectively (p = 0.001), demonstrating the antagonistic properties of losartan. We also noted a decreased maximal response to Ang II after incubation of losartan, with Emax of 51.1 +/- 7.08% and 41.9 +/- 4.70% (p = 0.05), respectively. In conclusion, this is the first report describing the contractile effect of Ang II and the antagonizing effects of losartan in isolated human coronary arteries.
| Original language | English |
|---|---|
| Journal | Journal of Cardiovascular Pharmacology |
| Volume | 32 |
| Issue number | 4 |
| Pages (from-to) | 662-4 |
| Number of pages | 3 |
| ISSN | 0160-2446 |
| Publication status | Published - Oct 1998 |
| Externally published | Yes |
Keywords
- Angiotensin II
- Angiotensin Receptor Antagonists
- Antihypertensive Agents
- Coronary Vessels
- Dose-Response Relationship, Drug
- Humans
- Losartan
- Muscle Contraction
- Muscle, Smooth, Vascular
- Vasoconstrictor Agents
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