Kawada T, Akiyama T, Shimizu S, Kamiya A, Uemura K, Li M, Shirai M, Sugimachi M. Detection of endogenous acetylcholine release during brief ischemia in the rabbit ventricle: a possible trigger for ischemic preconditioning.
Life Sci 2009;
85:597-601. [PMID:
19733187 DOI:
10.1016/j.lfs.2009.08.015]
[Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2009] [Revised: 08/19/2009] [Accepted: 08/25/2009] [Indexed: 10/20/2022]
Abstract
AIMS
To examine endogenous acetylcholine (ACh) release in the rabbit left ventricle during acute ischemia, ischemic preconditioning and electrical vagal stimulation.
MAIN METHODS
We measured myocardial interstitial ACh levels in the rabbit left ventricle using a cardiac microdialysis technique. In Protocol 1 (n=6), the left circumflex coronary artery (LCX) was occluded for 30min and reperfused for 30min. In Protocol 2 (n=5), the LCX was temporarily occluded for 5min. Ten minutes later, the LCX was occluded for 30min and reperfused for 30min. In Protocol 3 (n=5), bilateral efferent vagal nerves were stimulated at 20Hz and 40Hz (10V, 1-ms pulse duration).
KEY FINDINGS
In Protocol 1, a 30-min coronary occlusion increased the ACh level from 0.39+/-0.15 to 7.0+/-2.2nM (mean+/-SE, P<0.01). In Protocol 2, a 5-min coronary occlusion increased the ACh level from 0.33+/-0.07 to 0.75+/-0.11nM (P<0.05). The ACh level returned to 0.48+/-0.10nM during the interval. After that, a 30-min coronary occlusion increased the ACh level to 2.4+/-0.49nM (P<0.01). In Protocol 3, vagal stimulation at 20Hz and 40Hz increased the ACh level from 0.29+/-0.06 to 1.23+/-0.48 (P<0.05) and 2.44+/-1.13nM (P<0.01), respectively.
SIGNIFICANCE
Acute ischemia significantly increased the ACh levels in the rabbit left ventricle, which appeared to exceed the vagal stimulation-induced ACh release. Brief ischemia as short as 5min can also increase the ACh level, suggesting that endogenous ACh release can be a trigger for ischemic preconditioning.
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