Disruption of vagal efferent axon and nerve terminal function in the postischemic myocardium.
Despite the importance of vagal control over the ventricle, little is known regarding vagal efferent conduction and nerve terminal function in the postischemic myocardium. To elucidate postischemic changes in the cardiac vagal efferent neuronal function, we measured myocardial interstitial acetylcholine (ACh) levels by using in vivo cardiac microdialysis and examined the ACh responses to electrical stimulation of the vagi or local administration of ouabain in anesthetized cats. Sixty-minute occlusions of the left anterior descending coronary artery (LAD) followed by 60-min reperfusion abolished electrical stimulation-induced ACh release (20.4 +/- 3.9 vs. 0.9 +/- 0.4 nmol/l; means +/- SE, P < 0.01). In different groups of animals, 60-min LAD occlusion followed by 60-min reperfusion decreased but did not completely abolish ouabain-induced release of ACh (9.2 +/- 1.8 vs. 3.9 +/- 0.7 nmol/l; P < 0.05). These results indicate that function of the vagal efferent axon was completely interrupted, whereas the local ACh release was partially suppressed in the postischemic myocardium. The postischemic disruption of vagal efferent neuronal function might exert deleterious effects on cardiac regulation.
Kawada
Toru
T
Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Osaka 565 - 8565, Japan. torukawa@res.ncvc.go.jp
Yamazaki
Toji
T
Akiyama
Tsuyoshi
T
Mori
Hidezo
H
Uemura
Kazunori
K
Miyamoto
Tadayoshi
T
Sugimachi
Masaru
M
Sunagawa
Kenji
K
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001369:Axons / Q000502:physiology; D001794:Blood Pressure; D002415:Cats; D004195:Disease Models, Animal; D004558:Electric Stimulation; D006339:Heart Rate; D006352:Heart Ventricles / Q000187:drug effects / Q000294:innervation* / Q000503:physiopathology; D017551:Microdialysis; D017202:Myocardial Ischemia / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000378:metabolism*; D009476:Neurons, Efferent / Q000502:physiology; D010042:Ouabain / Q000494:pharmacology; D017729:Presynaptic Terminals / Q000502:physiology; D014630:Vagus Nerve / Q000503:physiopathology*
D010042:Ouabain; D000109:Acetylcholine