Influence of the Endothelium on the Elevation of Basal Tension in Aortae from Various Strains of Spontaneously Hypertensive Rats

Publisher Website
Google Scholar
Abstract
Summary: The active tone of aortic smooth muscle of spontaneously hypertensive rats and its modulation by endothelium were studied using spontaneously hypertensive rats (SHR), stroke-prone SHR (SHRSP), and malignant SHRSP (M-SHRSP) of Okamoto strain. Wistar-Kyoto (WKY) rats were also used as control normotensive rats. Blood pressure (BP) of the animals was higher in the following order: WKY < SHR < SHRSP < M-SHRSP. The active tone was obtained by removing extracellular calcium (Ca) in the absence of a stimulant (normal Tyrode's solution). Endothelium-denuded aortae of all hypertensive strains exhibited intrinsic active tone. The tone was greater in the same order as the BP: SHR < SHRSP < M-SHRSP. No active tone was observed in the aorta from WKY rats. This indicates that the Ca permeability of the cell membrane of aortae from hypertensive rats increases as the BP of the animals rises. The presence of the endothelium depressed the active tone completely in SHR aorta and markedly in SHRSP and M-SHRSP aortae. Since the endothelium-dependent relaxation is impaired in these hypertensive rats, both the increased Ca permeability and the impaired relaxing activity of the endothelium may contribute to the development of the active tone of blood vessels in spontaneously hypertensive rats.

This publication has 0 references indexed in Scilit: