Increase by NG-nitro-L-arginine methyl ester (L-NAME) of resistance to venous return in rats.
1. The effects of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), on mean circulatory filling pressure (MCFP), total peripheral resistance (TPR), cardiac output (CO) and resistance to venous return (Rv) were studied in rats. 2. In conscious, unrestrained rats, L-NAME (0.5-16 mg kg-1) dose-dependently increased mean arterial pressure (MAP) but not MCFP, an inverse index of venous compliance, either in the absence or presence of the ganglionic blocker mecamylamine (10 mg kg-1). 3. In pentobarbitone-anaesthetized rats, L-NAME (2, 4, 8 mg kg-1) increased MAP and reduced CO in a dose-related manner but did not change MCFP, TPR (+84, +140 and +192%) as well as Rv (+62, +72, +110%) were dose-dependently increased by L-NAME. 4. Our results show that L-NAME reduces CO by increasing arterial as well as venous resistances. L-NAME does not affect MCFP.
Wang
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YX
Department of Pharmacology & Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Lim
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SL
Pang
C C
CC
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002302:Cardiac Output / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects*; D007275:Injections, Intravenous; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors*; D019001:Nitric Oxide Synthase; D051381:Rats; D017207:Rats, Sprague-Dawley; D014655:Vascular Resistance / Q000187:drug effects; D014666:Vasomotor System / Q000187:drug effects; D014690:Venous Pressure / Q000187:drug effects*
D009569:Nitric Oxide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester