BJA Advance Access originally published online on September 3, 2004
British Journal of Anaesthesia 2004 93(5):698-704; doi:10.1093/bja/aeh262
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© The Board of Management and Trustees of the British Journal of Anaesthesia 2004
Effect of lidocaine on ischaemic preconditioning in isolated rat heart
Klinik für Anaesthesiologie, Universitätklinikum Düsseldorf, Postfach 10 10 07, D-40001 Düsseldorf, Germany
* Corresponding author. E-mail: schlack{at}uni-duesseldorf.de
Background. Lidocaine is frequently used as an agent to treat ventricular arrhythmias associated with acute myocardial ischaemia. Lidocaine is a potent blocker not only of sodium channels, but also of ATP-sensitive potassium channels. The opening of these channels is a key mechanism of ischaemic preconditioning. We investigated the hypothesis that lidocaine blocks the cardioprotection induced by ischaemic preconditioning.
Methods. Isolated rat hearts (n=60) were subjected to 30 min of no-flow ischaemia and 60 min of reperfusion. Control hearts (CON) underwent no further intervention. Preconditioned hearts (PC) received two 5-min periods of ischaemia separated by 10 min of reflow before the 30 min ischaemia. In three groups, lidocaine was infused at concentrations of 2, 10 or 20 µg ml1 for 5 min before the preconditioning ischaemia. Left ventricular developed pressure (LVDP) and infarct size (IS) (triphenyltetrazolium choride staining) were measured as variables of ventricular function and cellular injury, respectively.
Results. PC reduced IS from 24.8 (SEM 4.1) % to 4.0 (0.7) % of the area at risk (P<0.05). Adding 2 or 10 µg ml1 lidocaine had no effect on IS compared with PC alone (3.7 (0.7) %, 6.9 (1.8) %). Adding 20 µg ml1 lidocaine increased IS to 14.1 (2.5) % compared with PC (P<0.05). Baseline LVDP was similar in all groups (111.4 (2.1) mm Hg). Compared with CON, PC improved functional recovery (after 60 min of reperfusion; 52.3 (5.9) mm Hg vs 16.0 (4.0) mm Hg, P<0.01). The improved ventricular function was not influenced by addition of 2 or 10 µg ml1 lidocaine (47.3 (5.7) mm Hg, not significant; 45.3 (7.3) mm Hg, not significant), but was blocked by the infusion of 20 µg ml1 lidocaine (22.5 (8.0) mm Hg, P<0.01 vs PC).
Conclusions. Lidocaine blocks the cardioprotection induced by ischaemic preconditioning only at supratherapeutic concentrations.