Mesenteric vascular smooth muscle cells from SHR display increased Ca2+ responses to angiotensin II but not to endothelin-1

Touyz, R.M. , Tolloczko, B. and Schiffrin, E.L. (1994) Mesenteric vascular smooth muscle cells from SHR display increased Ca2+ responses to angiotensin II but not to endothelin-1. Journal of Hypertension, 12(6), pp. 663-673.

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Objective: To determine the differential calcium responses to two vasoconstrictor peptides, angiotensin II (Ang II) and endothelin-1, in vascular smooth muscle cells derived from mesenteric arteries from young and adult normotensive and hypertensive rats.

Methods: Effects of Ang II and endothelin-1 on cytosolic free calcium concentration in primary cultured unpassaged single vascular smooth muscle cells from mesenteric arteries of Wistar-Kyoto (WKY), Wistar and spontaneously hypertensive rats (SHR) aged 3, 9 and 17 weeks were examined microphotometrically using fura-2 methodology.

Results: Basal cytosolic free calcium concentration was significantly increased in cells from SHR aged 9 and 17 weeks compared with cells from age-matched WKY and Wistar rats. Ang II and endothelin-1 significantly increased cell cytosolic free calcium in all rat groups at all ages. Responses to low concentrations of Ang II (1 nmol/l) were significantly higher in cells from SHR aged 9 and 17 weeks than in age-matched controls. This was confirmed in cells from rats aged 17 weeks with full concentration-response curves, which also showed that the pD2 for Ang II for WKY rats was significantly different from that of SHR. In cells from SHR at all ages Ang II-stimulated cytosolic free calcium remained persistently high, whereas in cells from WKY and Wistar rats basal levels were reached within 100s after the maximal response. Low concentrations of endothelin-1 elicited significantly lower cytosolic free calcium responses in cells from SHR aged 17 weeks compared with age-matched controls. The time course of cytosolic free calcium responses to endothelin-1 were similar in the groups.

Conclusions: In primary cultured unpassaged mesenteric vascular smooth muscle cells from adult SHR, cytosolic free calcium concentration responses to Angll are enhanced, whereas responses to low concentrations of endothelin-1 are slightly reduced. The differential effects of these two vasoconstrictor peptides may contribute to their relative roles in modulating vascular smooth muscle cell cytosolic free calcium in SHR.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Touyz, Professor Rhian
Authors: Touyz, R.M., Tolloczko, B., and Schiffrin, E.L.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:Journal of Hypertension
ISSN (Online):1473-5598

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