Brief episode of myocardial ischemia before prolonged ischemia attenuates cardiac sympathetic nerve injury.
BACKGROUND
The aim of this study was to investigate the effects of brief ischemia before prolonged ischemia on cardiac sympathetic neural function. Brief ischemia inhibits the sympathetic neural release of norepinephrine (NE) during subsequent sustained ischemia. However, whether it can attenuate the neural function after sustained ischemia remains unknown.


RESULTS
Sympathetic neural function was assessed using 123I-metaiodobenzylguanidine (MIBG) in patients who with (Group I) or without angina (Group II) within 3 days prior to acute myocardial infarction. In the rat experiment, cardiac interstitial NE (iNE) with or without pretreatment of 5-min coronary ligation was determined during a 30-min occlusion. Differences between MIBG and Thallium-201 for the total defect score were significantly greater in Group II than in Group I (6.1 +/- 4.0 vs 0.4 +/- 4.4). Levels of iNE were less in rats with a 5-min pretreatment (7.3 +/- 2.3 vs 18.6 +/- 5.9 x 10(3) pg/ml, p < 0.01) and MIBG uptake of ischemic region was greater (0.061 +/- 0.029 vs 0.031 +/- 0.011 %kg dose/g, p < 0.05) compared with rats without the pretreatment.


CONCLUSIONS
A brief episode of ischemia attenuates the sympathetic neural injury caused by subsequent prolonged ischemia and this protective effect is associated with attenuation of NE release during the prolonged ischemia.
Nakadate
Teruo
T
The Second Department of Internal Medicine, University of Toyama, School of Medicine, Toyama, Japan.
Nozawa
Takashi
T
Matsuki
Akira
A
Nonomura
Makoto
M
Igarashi
Norio
N
Igawa
Akihiko
A
Inoue
Hiroshi
H
D019797:3-Iodobenzylguanidine / Q000008:administration & dosage; D000368:Aged; D000787:Angina Pectoris / Q000150:complications / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D000818:Animals; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D009638:Norepinephrine / Q000378:metabolism; D011859:Radiography; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D051381:Rats; D013564:Sympathetic Nervous System / Q000000981:diagnostic imaging / Q000293:injuries* / Q000378:metabolism / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine; D009638:Norepinephrine