Cerebral artery responses to pressure and flow in uremic hypertensive and spontaneously hypertensive rats

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 284; no. 4; p. H1212
• Main Authors: New, D I, Chesser, A M S, Thuraisingham, R C, Yaqoob, M M
• Format: Journal Article
• Language: English
• Published: United States 01-04-2003
• Subjects: Animals; Blood Flow Velocity; Blood Pressure; Endothelium, Vascular - physiology; Hypertension - etiology; Hypertension - physiopathology; Male; Middle Cerebral Artery - physiopathology; Muscle Contraction; Muscle, Smooth, Vascular - physiopathology; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Uremia - complications; Vasoconstriction
• ISSN: 0363-6135
• DOI: 10.1152/ajpheart.00644.2002

Impaired cerebral blood flow autoregulation is seen in uremic hypertension, whereas in nonuremic hypertension autoregulation is shifted toward higher perfusion pressure. The cerebral artery constricts in response to a rise in either lumen pressure or flow; we examined these responses in isolated middle cerebral artery segments from uremic Wistar-Kyoto rats (WKYU), normotensive control rats (WKYC), and spontaneously hypertensive rats (SHR). Pressure-induced (myogenic) constriction developed at 100 mmHg; lumen flow was then increased in steps from 0 to 98 microl/min. Some vessels were studied after endothelium ablation. Myogenic constriction was significantly lower in WKYU (28 +/- 2.9%) compared with both WKYC (39 +/- 2.5%, P = 0.035) and SHR (40 +/- 3.1%, P = 0.018). Flow caused constriction of arteries from all groups in an endothelium-independent manner. The response to flow was similar in WKYU and WKYC, whereas SHR displayed increased constriction compared with WKYU (P < 0.001) and WKYC (P < 0.001). We conclude that cerebral myogenic constriction is decreased in WKYU, whereas flow-induced constriction is enhanced in SHR.