Motor reactivity of isolated heart of grass-snake (Natrix natrix L.) effects of temperature and pH.

It was demonstrated that isolated heart of the grass-snake perfused with a fluid of properly chosen components can pulsate without abnormalities for at least 12 hours, and the rate of its contractions depends, in a high degree, on the temperature. This relationship is a logarithmic one, although in the temperature range from 10 degrees to 22 degrees C the regression is linear. The highest temperature at which the heart rhythm was still regular was 34 degrees C. The isolated heart contracted rhythmically and normally even when pH of the nutritive solution differed considerably from the physiological value, showing greater tolerance of contractility in the case of solutions in the alkaline range of pH. It seems that the pH range from 6.5 to 9.5 is the optimal one for maintaining the function of grass-snake heart.