Different mechanisms of L-arginine induced dilation of brain arterioles in normotensive and hypertensive rats
Abstract
We evaluated the response of pial arterioles to L-arginine in anesthetized normotensive rats and spontaneously hypertensive rats equipped with a closed cranial window. Topical application of 10(-6)-10(-4) mol/l L-arginine, which is known to be the endogenous substrate for the synthesis of nitric oxide, induced dose-dependent arteriolar vasodilation. The response was more pronounced in hypertensive than in normotensive rats (at the concentration of 10(-4) mol/l L-arginine: 18.3 +/- 3.3% vs. 6.7 +/- 1.7%, respectively, means +/- S.E.). The stereoisomer D-arginine had no effect in hypertensive rats. Topical application of the nitric oxide synthase inhibitor N-nitro-L-arginine converted L-arginine-induced dilation to constriction in normotensive and hypertensive rats. The cyclooxygenase inhibitor indomethacin (5 micrograms/ml cerebrospinal fluid) also blocked the dilation in both strains. Photochemical endothelial injury blocked L-arginine-induced dilation in normotensive rats, but only partly antagonized the response in hypertensive animals. Intravenous or topical pretreatment with the free radical scavenger superoxide dismutase significantly reduced the dilating response to 10(-4) mol/l L-arginine in hypertensive rats. Superoxide...Continue Reading
References
Citations
Endothelium-dependent and -independent vasoreactivity of rat basilar artery in chronic heart failure
Related Concepts
Related Feeds
CSF & Lymphatic System
This feed focuses on Cerebral Spinal Fluid (CSF) and the lymphatic system. Discover the latest papers using imaging techniques to track CSF outflow into the lymphatic system in animal models.