Upregulation of neuronal nitric oxide synthase in skeletal muscle by swim training.
Exercise enhances cardiac output and blood flow to working skeletal muscles but decreases visceral perfusion. The alterations in nitric oxide synthase (NOS) activity and/or expression of the cardiopulmonary, skeletal muscle, and visceral organs induced by swim training are unknown. In sedentary and swim-trained rats (60 min twice/day for 3-4 wk), we studied the alterations in NOS in different tissues along with hindquarter vasoreactivity in vivo during rest and mesenteric vascular bed reactivity in vitro. Hindquarter blood flow and conductance were reduced by norepinephrine in both groups to a similar degree, whereas N(G)-nitro-L-arginine methyl ester reduced both indexes to a greater extent in swim-trained rats. Vasodilator responses to ACh, but not bradykinin or S-nitroso-N-acetyl-penicillamine, were increased in swim-trained rats. Ca(2+)-dependent NOS activity was enhanced in the hindquarter skeletal muscle, lung, aorta, and atria of swim-trained rats together with increased expression of neuronal NOS in the hindquarter skeletal muscle and endothelial NOS in the cardiopulmonary organs. Mesenteric arterial bed vasoreactivity was unaltered by swim training. Physiological adaptations to swim training are characterized by enhanced hindquarter ACh-induced vasodilation with upregulation of neuronal NOS in skeletal muscle and endothelial NOS in the lung, atria, and aorta.
Tatchum-Talom
R
R
Department of Pharmacology and the Cardiovascular Risk Factor Reduction Unit, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5.
Schulz
R
R
McNeill
J R
JR
Khadour
F H
FH
D000818:Animals; D001011:Aorta / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D002320:Cardiovascular Physiological Phenomena; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006614:Hindlimb / Q000098:blood supply; D008168:Lung / Q000201:enzymology; D008297:Male; D008638:Mesenteric Arteries / Q000502:physiology; D018482:Muscle, Skeletal / Q000201:enzymology*; D009206:Myocardium / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052248:Nitric Oxide Synthase Type I; D009638:Norepinephrine / Q000494:pharmacology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D013550:Swimming; D015854:Up-Regulation; D014655:Vascular Resistance / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014666:Vasomotor System / Q000502:physiology
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine