Endothelin and mechanical properties of the carotid artery in Wistar-Kyotoand spontaneously hypertensive rats

The aim of this study is to evaluate the role of endothelin in the control of the static mechanical properties of in vitro carotid arteries from 14-we ek-old Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). An in vitro preparation in which the artery was allowed to longitudinally elongat e similarly to the in situ carotid artery was employed. The diameter of in vitro carotid arteries subjected to static pressures (from 25 to 200 mmHg i n 25 mmHg steps) was determined by videomicroscopy and computer-assisted im age analysis, the cross-sectional compliance- and distensibility-pressure c urves being then derived. The role of endothelin was assessed by incubating carotid arteries with the selective ETA and ETB endothelin receptor antago nists BQ123 and BQ788, respectively. These effects were compared with those observed under control conditions, as well as with those following complet e abolition of vascular smooth muscle tone by potassium cyanide (KCN). Caro tid diameter was significantly larger, and compliance and distensibility si gnificantly smaller, in SHR compared to WKY rats. Local incubation with BQ1 23 was associated with significant dilations as well as significant increas es in cross-sectional compliance and distensibility in both strains. This w as even more pronounced with KCN, while BQ788 had no effect. The results of the present study suggest that: (i) endothelin exerts a tonic stiffening e ffect on the in vitro common carotid artery; (ii) this effect is mediated v ia the ETA endothelin receptor, and (iii) the stiffening effect of endothel in is exerted to a similar extent in the carotid arteries of normotensive W KY and SHR rats. (C) 1999 Elsevier Science B.V. All rights reserved.