INTERACTION OF THYROID-HORMONE AND HEPARIN IN POSTISCHEMIC MYOCARDIALRECOVERY

Background. Triiodothyronine (T-3) administration can improve postisch emic myocardial recovery. Heparin can interfere with cellular binding of T-3. Introduction of heparin into an isolated heart model may inter fere with this effect. Methods. Four groups of 8 rat hearts were place d on a modified Lanegendorff apparatus. All groups underwent 15 minute s of perfusion with modified Krebs-Henseleit solution (KH), followed b y 20 minutes of normothermic global ischemia and 30 minutes of reperfu sion. Group I underwent reperfusion with KH. Group II underwent reperf usion with KH and 1 x 10(-6) mol/L of T-3. In group III, hearts underw ent preischemic perfusion with heparinized KH (1,000 U/L) and reperfus ion with KH containing 1 x 10(-6) mol/L of T-3 and 1,000 U/L of hepari n. In group IV, rats were given heparin at 2,000 IU/kg 30 minutes befo re sacrifice, and isolated hearts were reperfused with KH and 1 x 10(- 6) mol/L bf T-3. A latex balloon in the left ventricle monitored hemod ynamic variables. Results. Left ventricular developed pressure through out postischemic reperfusion was greater in all the groups receiving T -3 when compared with group I. Group II showed significantly greater r ecovery than either group III (p < 0.05) or group IV (p < 0.05). Concl usions. Addition of T-3 to the reperfusate enhances postischemic myoca rdial recovery in the isolated heart model, whereas addition of hepari n reduces this effect.