P. Ferdinandy et al., VENTRICULAR OVERDRIVE PACING-INDUCED PRECONDITIONING AND NO-FLOW ISCHEMIA-INDUCED PRECONDITIONING IN ISOLATED WORKING RAT HEARTS, Journal of cardiovascular pharmacology, 25(1), 1995, pp. 97-104
To examine preconditioning induced by short periods of ventricular ove
rdrive pacing (VOP) as compared with that induced by no-flow ischemia,
we subjected isolated working rat heart to 10-min coronary artery occ
lusion (test ischemia) followed by 3-min reperfusion after three inter
mittent periods of VOP (10 Hz) or 5-min no-flow ischemia, respectively
. In the nonpreconditioned group, coronary occlusion decreased aortic
flow (AF) from 46.6 +/- 2.4 to 13.7 +/- 1.7 ml/min and increased left
ventricular end-diastolic pressure (LVEDP) from 0.53 +/- 0.05 to 2.02
+/- 0.07 kPa. Preconditioning by VOP or no-flow ischemia significantly
increased AF to 25.1 +/- 2.3 ml/min (p < 0.001) and to 27.3 +/- 1.4 m
l/min (p < 0.001) and decreased LVEDP to 1.38 +/- 0.1 kPa (p < 0.001)
and to 1.65 +/- 0.05 kPa (p < 0.05), respectively, after test ischemia
. Glibenclamide 10(-7) M which blocked the antiischemic effect of the
ATP-sensitive K+-channel (K-ATP) opener cromakalim, inhibited VOP-indu
ced protection (AF 20.3 +/- 2.3 ml/min; LVEDP 1.82 +/- 0.15 kPa), but
did not affect no-flow ischemia-induced preconditioning [AF 26.6 +/- 2
.4 ml/min (p < 0.001), LVEDP 1.60 +/- 0.07 kPa (p < 0.01)]. VOP and no
-flow ischemia precondition heart, however their cardioprotective mech
anisms may be different in terms of K-ATP activation in rats.