L-PROPIONYLCARNITINE AND MYOCARDIAL PERFORMANCE IN STUNNED PORCINE MYOCARDIUM

Recently, we showed that L-propionylcarnitine did not affect recovery of regional contractile function of porcine myocardium subjected to 1 h of low-flow ischemia followed by 2 hr of reperfusion. In that study, ischemia may have been too severe and/or the duration of reperfusion too short to detect a beneficial effect of the compound. Therefore, in the present study we investigated the effects of saline (control group; n = 14) or pretreatment with L-propionylcarnitine (3 days of 50 mg/kg p.o. b.i.d. + 50 mg/kg i.v. prior to the experiment; n = 13) on recovery of regional contractile function of the myocardium in open-chest anesthetized pigs, subjected to two cycles of 10 min of left anterior descending coronary artery (LADCA) occlusion, each followed by 30 min of reperfusion. In the control animals, at the end of the second reperfusion period, systemic vascular resistance had increased by 18%, which, however, was not observed in the L-propionylcarnitine-treated pigs. In the control group, during the first occlusion, systolic segment length shortening (SSLS) of the LADCA-perfused area decreased from 18.5 +/- 5.5% to - 3.7 = 3.2%. After 30 min of reperfusion, SSLS of the LADCA-perfused area had only partially recovered to 6.2 +/- 5.9%. During the second occlusion-reperfusion cycle similar values for SSLS were observed. In the treated animals, SSLS of the LADCA-perfused area was slightly improved after the second occlusion-reperfusion cycle (p = 0.056). This effect did not result in an overall improvement in cardiac pump function. We conclude that in a model of myocardial stunning, L-propionylcarnitine prevents systemic vasoconstriction in response to ischemia and reperfusion and, possibly as a result of this effect, slightly ameliorates post-ischemic hypofunction.