[Restoration of contractions of isolated heart arrested in result of progressing hypothermia with electrical stimuli and no warming up of the heart].

In the rat isolated heart, the effect of cooling with the velocity 0.2 degrees C/min and its stimulation with rectangle electrical pulses (19 Hz, 100 ms, 1-5 V amplitude) on the heart mechanical activity in mcWatt/g was studied as the product of heart shortening on contraction strength and heart rate. The heart shortening was measured by the Langendorf method. Heart contractions activated the recording system with the aid of a hook at the apex. The Ringer-Lokk solution served as perfusate pumped with peristaltic pump. After cold arrest of automatic contractions (on the average at 9.3 +/- 0.7 degrees C), the heart continued to respond with contractions to electrical pulses of 5 V amplitude, the power of the heart contractions at 10 degrees C being on the average 35 % of the initial power at 20 degrees C. Excitability and contractility of the heart terminate at 5.3 +/- 0.4 degrees C.