| RESEARCH PAPER
|Year : 2000 | Volume
| Issue : 1 | Page : 15-20
Study of effects on the sensitivity of vascular and extravascular tissues in ethinyl estradiol-induced hypertensive rats
BS Thakre, KK Shah, JD Bhatt
Objective: To investigate the effects on the sensitivity of isolated vascular and extravascular tissues to various agonists in chronic ethinyl estradiol (EE)-treated hypertensive male rats.
Methods: The effect of chronic EE treatment (1.5 mg/kg/day, i.m.) for 3 weeks to rats on the acetylcholine (ACh)-induced relaxation of phenylephrine (PE) precontracted isolated rat aortic strip with intact endothelium and on the sensitivity of isolated rat anococcygeus muscle to various agonists were studied.
Results: Chronic EE treatment to rats significantly decreased the maximal relaxation induced by ACh in the isolated aortic strip with intact endothelium. Chronic EE treatment to rats produced significant increase in pD 2 value of PE and 5-hydroxytryptamine (5-HT) and significant decrease in pD2 value of ACh without modifying that of potassium chloride (KCI) in isolated anococcygeus muscle preparation.
Conclusions: In chronic EE-treated hypertensive model of rat, ACh-induced endothelium dependent relaxation of isolated aortic strip is significantly impaired, suggesting reduced vascular relaxation could be a contributing factor in EE-induced hypertension. Also isolated rat anococcygeus muscle exhibited supersensitivity to PE and 5-HT after chronic EE treatment confirming the neuronal uptake blocking property of estrogen.
B S Thakre
Source of Support: None, Conflict of Interest: None