L-arginine dilates cheek pouch arterioles in hamsters with hereditary cardiomyopathy but not in controls.
The purpose of this study was to determine whether suffusion of L-arginine alone induces vasodilation in the cheek pouch of hamsters with hereditary cardiomyopathy in comparison with controls, and whether these effects are mediated by the L-arginine/nitric oxide biosynthetic pathway. Using intravital microscopy, we found that suffusion of L-arginine for 20 minutes induced a significant, stereospecific concentration-dependent vasodilation in hamsters with hereditary cardiomyopathy but not in controls (p < 0.05). These responses were abrogated by suffusion of the nitric synthase inhibitor NG-L-arginine methyl ester (L-NAME) but not by suffusion of D-NAME. Suffusion of nitroglycerin, a nitric oxide donor, induced significant vasodilation of similar magnitude in both groups (p < 0.05). L-NAME had no significant effects on nitroglycerin-induced responses in both groups. We conclude that direct application of L-arginine alone to the peripheral microcirculation in cardiomyopathy induces significant vasodilation that is mediated, most likely, via a nitric oxide-dependent mechanisms(s). We suggest that a reversible, L-arginine-responsive impairment in the constitutive L-arginine/nitric oxide biosynthetic pathway is present in the peripheral microcirculation in cardiomyopathy.
Rubinstein
I
I
Department of Medicine (M/C 787), University of Illinois at Chicago 60612-7323.
Mayhan
W G
WG
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology*; D001160:Arterioles / Q000187:drug effects; D009202:Cardiomyopathies / Q000235:genetics* / Q000503:physiopathology*; D002610:Cheek / Q000098:blood supply*; D006224:Cricetinae; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D012016:Reference Values; D014664:Vasodilation
D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester