Evidence of L-arginine/nitric oxide pathway in endothelium and smooth muscle of human internal mammary artery.
The L-arginine-nitric oxide (NO) pathway was investigated in human internal mammary artery (HIMA) in vitro. HIMA rings were mounted in organ bath, and then incubated in Krebs buffer for 1 to 8 hrs, relaxing agents were tested. Under these conditions, L-arginine (0.1 microM - 1 mM) elicited only minor relaxation after 2 hr incubation, whereas with increased incubation time (4, 6, 8 hrs), the concentration-dependent relaxation to L-arginine increased significantly in endothelium-intact and -denuded vessels. NG-nitro-L-arginine (100 microM) or NG-monomethyl-L-arginine (100 microM) or methylene blue (2.7 microM) partially inhibited L-arginine relaxation. In endothelium-intact HIMA and in both types of rings A23187 (10 microM) and L-arginine (100 microM), respectively, increased the concentration of NO in medium and cGMP content of vascular tissues. These increases were partially inhibited by NG-nitro-L-arginine (100 microM) or methylene blue (2.7 microM).


CONCLUSIONS
in smooth muscle of HIMA L-arginine-NO conversion is calcium independent, which is different from that in endothelium.
Qi
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Lo Clinic, Oak Park, IL.
Chen
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Nottin
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Mace
L
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Herve
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P
Weiss
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M
D000109:Acetylcholine / Q000494:pharmacology; D000368:Aged; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000001:Calcimycin / Q000494:pharmacology; D006152:Cyclic GMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008323:Mammary Arteries / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D008875:Middle Aged; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D019323:omega-N-Methylarginine
D019335:Nitroarginine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000001:Calcimycin; D001120:Arginine; D006152:Cyclic GMP; D000109:Acetylcholine