Temperature-dependence of the effect of trifluoperazine as a protective agent during cardioplegia in the isolated working rat heart.

The duration of ischemia resulting in 50% post-ischemic recovery of hemodynamic functions was 25 min in the control isolated working rat hearts and increased to 45 min in the hearts subjected to normothermic cardioplegia plus normothermic global ischemia (36 degrees C) and to 180 min in the hearts subjected to hypothermic cardioplegia and hypothermic ischemia (22 degrees C). Addition of 10(-6) M trifluoperazine to the normothermic St. Thomas' cardioplegic solution considerably improved the protective properties of the solution as assessed by the functional recovery of the heart. Under conditions of hypothermic ischemic arrest the drug failed to improve the protective properties of cardioplegic solution, suggesting a common modality between hypothermia and trifluoperazine-induced protection.