Characterization of endothelium-dependent vasodilation and vasoconstriction in coronary arteries from spontaneously hypertensive rats

• Published in: American journal of hypertension 1996-05, Vol.9 (5), p.475-483
• Main Authors: Fuchs, Leslie C., Nuno, Dan, Lamping, Kathryn G., Kim Johnson, Alan
• Format: Article
• Language: English
• Subjects: acetylcholine; Adrenergic alpha-Agonists - pharmacology; Animals; Arterial hypertension. Arterial hypotension; Biological and medical sciences; Blood and lymphatic vessels; Blood Pressure - drug effects; Cardiology. Vascular system; coronary arterioles; Coronary Vessels - anatomy & histology; Coronary Vessels - physiology; endothelin-1; Endothelium, Vascular - physiology; Experimental diseases; Heart Rate - drug effects; hydralazine; Hydralazine - pharmacology; Hypertension - genetics; Hypertension - physiopathology; In Vitro Techniques; isoproterenol; Isoproterenol - pharmacology; Male; Medical sciences; Muscle, Smooth, Vascular - drug effects; phenylephrine; Phenylephrine - pharmacology; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Receptors, Adrenergic, alpha - drug effects; Receptors, Adrenergic, alpha - physiology; Space life sciences; Spontaneously hypertensive rats; Vasoconstriction - drug effects; Vasoconstriction - physiology; Vasoconstrictor Agents - pharmacology; Vasodilation - drug effects; Vasodilation - physiology; Vasodilator Agents - pharmacology; Wistar-Kyoto rats
• ISSN: 0895-7061; 1879-1905; 1941-7225
• DOI: 10.1016/0895-7061(95)00441-6

Coronary artery disease often occurs in patients with hypertension. The present study was designed to evaluate coronary vascular function in isolated coronary arteries of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats and to determine the effect of antihypertensive treatment on coronary vascular responsiveness. Male SHR and WKY rats (12 to 14 weeks old) were divided into control and hydralazine-treated (120 mg/L drinking water for 10 days) groups. After 10 days, arterial pressure and heart rate were recorded while rats were conscious and unrestrained. Left ventricular coronary arteries (200 to 300 μm diameter) were isolated and intraluminal diameter was continuously recorded while vessels were maintained at a constant intraluminal pressure of 40 mm Hg. Relaxation of coronary arteries to both acetylcholine and nitroprusside was slightly, but significantly, enhanced in vessels from SHR compared to WKY rats. The enhanced relaxation was a specific effect, since isoproterenol induced similar relaxation in coronary arteries from SHR and WKY rats. Contraction to phenylephrine, but not endothelin-1, was augmented in coronary arteries from SHR compared to WKY rats. Treatment with hydralazine significantly lowered arterial pressure in SHR and WKY rats, but did not alter the enhanced contraction to phenylephrine or the enhanced relaxation to acetylcholine and nitroprusside in coronary arteries from SHR. These results indicate that coronary arteries of 12 to 14 week-old SHR do not have impaired endothelium-dependent relaxation, but do exhibit enhanced α-adrenoreceptor-mediated contraction that is not reduced by lowering arterial pressure.