Effects of brief ischaemia on myocardial acetylcholine and noradrenaline levels in anaesthetized cats.
Although brief ischaemic events make the myocardium tolerant to subsequent prolonged ischaemia, known as ischaemic preconditioning, whether brief ischaemia also affects neural regulation at the in vivo heart remains unknown. We examined the effects of brief ischaemia on myocardial interstitial acetylcholine (ACh) and noradrenaline (NA) levels in anaesthetized cats (n = 6). Baseline ACh and NA levels were 0.65 +/- 0.13 and 0.66 +/- 0.17 nmol l(-1) (mean +/- SE), respectively. Two sets of 5-min brief occlusion followed by 20-min reperfusion of the left anterior descending coronary artery (LAD) significantly increased the myocardial interstitial ACh level to 4.6 +/- 0.7 nmol l(-1) (P < 0.01), while not affecting the myocardial interstitial NA level. Subsequent 60-min LAD occlusion significantly increased the ACh and NA levels to 34.9 +/- 6.0 and 96.5 +/- 17.0 nmol l(-1) (P < 0.01), respectively. Vagotomy abolished the myocardial interstitial ACh release during brief ischaemia and attenuated the ACh release during subsequent 60-min ischaemia (n = 6). In contrast, vagotomy did not affect the subsequent ischaemia-induced myocardial interstitial NA release. We conclude that the brief ischaemia affects myocardial interstitial ACh release but not NA release in the ischaemic myocardium in vivo.
Kawada
Toru
T
Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Suita, Osaka, Japan. torukawa@res.ncvc.go.jp
Yamazaki
Toji
T
Akiyama
Tsuyoshi
T
Mori
Hidezo
H
Inagaki
Masashi
M
Shishido
Toshiaki
T
Takaki
Hiroshi
H
Sugimachi
Masaru
M
Sunagawa
Kenji
K
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002415:Cats; D023921:Coronary Stenosis / Q000378:metabolism / Q000503:physiopathology; D006321:Heart / Q000294:innervation*; D019157:Ischemic Preconditioning, Myocardial; D017202:Myocardial Ischemia / Q000378:metabolism* / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D017779:Sympathetic Fibers, Postganglionic / Q000378:metabolism*; D009435:Synaptic Transmission / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology; D014630:Vagus Nerve / Q000378:metabolism*
D000109:Acetylcholine; D009638:Norepinephrine