title: Chronic exercise enhances endothelium-mediated dilation in spontaneously hypertensive rats.
abstract: This study investigated the effect of physical training on endothelial function in spontaneously hypertensive rats (SHR). After 3 months, in conscious trained- and untrained-SHR body weight, systolic blood pressure and heart rate were 220 +/- 6 g vs 271 +/- 9 g, 172 +/- 7 mmHg vs 210 +/- 8 mmHg and 314 +/- 10 vs. 348 +/- 12 beats/min, respectively. In vitro, the dose-response curves of norepinephrine in isolated intact aortic and mesenteric rings form the exercise trained-SHR were significantly lower than those from the untrained-SHR. With denuded preparations, norepinephrine concentration-response curves were shifted to the left both in the trained- and untrained-SHR. This shift in the trained-SHR exceeded that in the untrained-SHR. The vasodilator response to acetylcholine in the trained-SHR was significantly greater than that in the untrained-SHR. Either N omega-nitro-L-arginine (100 mumol/l) or methylene blue (10 mumol/l) inhibited acetylcholine-induced vasodilator effect in aorta of trained- and untrained-SHR, but not in mesenteric artery of trained-SHR. Tetraethylammonium (10 mmol/l) inhibited significantly the N omega-nitro-L-arginine and methylene blue-resistant relaxation in mesenteric artery of trained-SHR, but not only by indomethacin (10 mumol/l). Collectively, these data demonstrate that chronic exercise increases EDRF/EDHF production (presumably by increasing endothelial shear stress), and may contribute to the enhanced effects of post-exercise hypotension.
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000503:physiopathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006339:Heart Rate; D006973:Hypertension / Q000503:physiopathology*; D008074:Lipoproteins / Q000097:blood; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology; D008751:Methylene Blue / Q000494:pharmacology; D019335:Nitroarginine; D005996:Nitroglycerin / Q000494:pharmacology; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D011918:Rats, Inbred SHR; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D008074:Lipoproteins; D014665:Vasodilator Agents; D019335:Nitroarginine; D001120:Arginine; D005996:Nitroglycerin; D000109:Acetylcholine; D008751:Methylene Blue; D009638:Norepinephrine