Responses of aortic ring vascular smooth muscle in rats with hyperthyroidism to phenylephrine and potassium chloride

Aim: The effects of thyroid hormones on receptor numbers and pharmacological contractile responses of vascular smooth muscle appear to be controversial. The aim of the present study was to evaluate the vascular responses to potassium chloride (KCl) and phenylephrine (PE) in a rat model of hyperthyroidismMethods:The study was approved by the Ethical Committee of The Animal Research of Ataturk University. Wistar Albino type of rats were divided into two groups: Control (n=5) and hyperthyroidism(n=5). Hyperthyroidism was induced by intraperitoneal injection of L-thyroxine (0.3mg/kg/day) for two-weeks. The thoracic aorta rings suspended in an isolated organ bath with Krebs-Henseleit buffer. Maximal tension was measured in response to KCl and PE in rings with intact endothelium. The data were evaluated by one-way ANOVA with post-hoc Tukey test.Results:Our results showed that contractile responses of the aortic rings of with hyperthyroidism to PE (10-7M) were significantly reduced compared to the control group (1.34±0.43g, 3.26±0.39g, respectively, p