RELEASE OF ISCHEMIA IN PACED RAT LANGENDORFF HEARTS BY SUPPLY OF L-CARNITINE - ROLE OF ENDOGENOUS LONG-CHAIN ACYLCARNITINE

Rat Langendorff hearts perfused with media that do not contain erythro cytes or fluorocarbon as oxygen carriers are borderline aerobic during 5 Hz pacing. This follows from the release of catabolic products meas ured: lactate, urate and Iysophosphatidylcholine (IysoPC). Addition of L-carnitine to the perfusion medium reduced the level of these compou nds, while the release of long-chain acylcarnitine (LCAC) increased. P reviously, we found (Biochim Biophys Acta 847:62-66,1985) that micromo lar LCAC protects membranes during reperfusion after ischemia, Therefo re, the observed inverse relation between LCAC and the other compounds measured suggests that LCAC is the basis of an acute relief of immine nt ischemia by carnitine addition. LCAC may be released from various c ell types, including vascular endothelium, as demonstrated. The cation ic amphiphilic nature of LCAC is responsible for protection of membran e functions in imminent ischemia.