NG-nitro-L-arginine methyl ester-induced norepinephrine release from cardiac sympathetic nerve endings in anesthetized cats.
Using the cardiac dialysis technique in the anesthetized cat, we examined the effects of NG-nitro-L-arginine methyl ester (L-NAME, a nitric oxide (NO) synthase inhibitor, 100 mM) on sympathetic modulation. Local administration of L-NAME induced increases in dialysate norepinephrine (NE) levels, which were not affected by the addition of omega-conotoxinGVIA. High-potassium (high K+)-evoked increases in dialysate NE levels were suppressed by addition of L-NAME. To confirm the involvement of NO in the NE releasing action, we compared dialysate NE levels during the administration of L-NAME or D-NAME and no significant differences between them. L-NAME induces spontaneous non-exocytotic NE release but suppresses exocytotic NE release by high K+. L-NAME may interact with both NE transport and NE release mechanisms. However, NO may contribute little to the amounts of NE released by L-NAME.
Takauchi
Yuji
Y
Department of Anesthesiology and Surgical Intensive Care Unit, National Cardiovascular Center, Suita, Osaka 565-8565, Japan.
Yamazaki
Toji
T
Akiyama
Tsuyoshi
T
Sunagawa
Kenji
K
D000758:Anesthesia; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002415:Cats; D003956:Dialysis; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006321:Heart / Q000294:innervation; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D009411:Nerve Endings / Q000187:drug effects* / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors; D020866:omega-Conotoxin GVIA / Q000494:pharmacology
D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D020866:omega-Conotoxin GVIA; D011188:Potassium; D019331:NG-Nitroarginine Methyl Ester; D009638:Norepinephrine