Endothelium-dependent dilation to L-arginine in isolated rat skeletal muscle arterioles.
The vascular actions of L-arginine (L-Arg) were studied in isolated, pressurized first-order rat cremaster muscle arterioles (93 +/- 2.9 microns) bathed in a Krebs bicarbonate-buffered solution, pH 7.4, equilibrated with 21% O2-5% CO2. Arterioles were studied before and after either the administration of NG-nitro-L-arginine (L-NNA, 10(-3) M), an inhibitor of the synthesis of endothelium-derived relaxing factor (EDRF), or the removal of the endothelium. Acetylcholine (ACh, 10(-8) and 10(-6) M), sodium nitroprusside (SNP, 10(-8) M) and phenylephrine (PE, 10(-7) M) evoked dilation and constriction, respectively. L-Arg, (10(-5)-10(-3) M) the precursor of EDRF, evoked dose-dependent arteriolar dilation; whereas D-arginine (D-Arg, 10(-5)-10(-3) M) was without any significant effect. Administration of L-NNA significantly reduced basal diameters and significantly inhibited the arteriolar dilations to both ACh and L-Arg but had no effect on the dilation to SNP. Removal of the arteriolar endothelium with air inhibited dilations to both ACh and L-Arg, had no effect on responses to SNP, and potentiated vasoconstrictor responses to PE. These findings suggest that in skeletal muscle arterioles the dilations to ACh and L-Arg are endothelium dependent and that microvascular endothelium modulates constrictor responses to PE. Thus EDRF may play an important role in the local regulation of arteriolar resistance and blood flow.
Sun
D
D
Department of Physiology, New York Medical College, Valhalla 10595.
Messina
E J
EJ
Koller
A
A
Wolin
M S
MS
Kaley
G
G
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology*; D001160:Arterioles / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009132:Muscles / Q000098:blood supply*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D019335:Nitroarginine; D051381:Rats; D011919:Rats, Inbred Strains; D014664:Vasodilation / Q000502:physiology*
D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine; D000109:Acetylcholine