[Study on the effect of cardioplegia induced by kalium-verapamil-propranolol in different temperatures on the function of immature rat heart].

Objective: To explore the appropriate temperature of the kalium-verapamil-propranolol (KVP) cardioplegia by observation of the effect on the function of the immature rat heart.

Methods: Isolated hearts from immature rats were perfused by Langendorff method, and assigned to 1 of the following 5 groups (n = 6-8): control, continuously perfused for 170 min at 36 degrees C, normal temperature, normal perfused for 20 min, changed to perfuse with KVP for 3 min then no perfusion 87 min (ischemia 90 min), followed by 60 min reperfusion. 3 groups of low temperature, perfused for 15 min, cool down to 32 degrees C, 28 degrees C and 24 degrees C especially in 5 min, and at 20th min. heart rate (b/min), tension (g), contraction force (g), peak systolic velocity (dT/dt(max)), peak diastole velocity (dT/dt(max)), coronary flow (Drop/min) were monitored during the whole perfusion.

Results: Compared to control group, the heart tension increased after 50 min KVP ischemia. The protection of KVP in normal temperature (36 degrees C) was better than lower temperature (32 degrees C, 28 degrees C, 24 degrees C) such as reducing bad contraction, keeping normal myocardium tension,recovering heart rate, recovering the fuction of contraction force and protecting the coronary flow.

Conclusion: The KVP cardioplegia in normal temperature has the better effect than that in hypothermia to protect the immature heart.