ENDOTHELIN AND HYPERTENSION
Meral TUNCER* °, Oguzhan YILDIZ**
* Hacettepe University, Faculty of Medicine, Department of Pharmacology, 06100 Sihhiye, Ankara, TURKEY.
**GATA and Faculty of Medicine, Department of Medicinal Pharmacology, Ankara, TURKEY.
°Corresponding Author

Summary:
The hall-mark of hypertension is an increase in peripheral vascular resistance.This increase is considered to be related to an increase in tone of resistance arteries as well as to structural changes (i.e., vascular remodeling ) of these blood vessels. Accordingly, hypertension research has focused on identifying the mediator or mediators responsible for this phenomenon. The search for additional mediator causing the increase in peripheral vascular resistance in hypertension continues. Endothelins are a family of potent vasoconstrictor peptides released by endothelial cells: endothelin-1 (endothelin), endothelin-2, endothelin-3. The question of whether endothelin is involved in hypertension and its complications, or both cannot be solved at this point; however, several aspects can be addressed. Endothelin-1 causes biphasic changes in arterial blood pressure and of peripheral resistance in several vascular beds : an initial transient decrease (due to release of nitric oxide, prostacyclin, or both from the endothelium) followed by a sustained increase (mainly due to direct activation of vascular smooth muscle). Few studies indicate that the circulating levels of the peptide are augmented in hypertension. Likewise, the information available on changes in responsiveness to endothelins in blood vessels from hypertensive animals is controversial. Until the effect of selective antogonists on the production or action of the peptide can be determined in hypertensive patients, caution must be exerted when implying a role for endothelin in the pathophysiologhy of hypertension.

Keywords:
Endothelin,hypertension