[Dynamics of various integral indices of individual changes of heat-resistance of isolated frog muscles kept in...

A study was made of the dynamics of the heat resistance (HR) mean level, of the correlation between the initial individual HR level and the value and direction of this level shifting, and of the pattern of correlation between HR levels of pair sartoria muscles and variability of HR level in muscles kept at 5-6 degrees C in the Ringer for 12 days. A two-phase changes in the mean HR level of muscles was revealed that involved its increase by 48% within one day of maintenance in the Ringer solution followed by its decrease by 14% in 6 days. On the first steps of muscle maintenance in the Ringer solution, a negative correlation was noticed between the initial HR level and the value and direction of its shifting, in addition to narrowing the range of variability of muscle HR level. All these events were accompanied by phase fluctuations in the correlation coefficient between HR levels of pair muscles. By the end of experiment the range of variability of the HR level was seen to increase, and the earlier positive correlation between pair muscle HR levels appeared either to change or to be a negative one. The increase in the range of variability preceded the decrease in the mean level of muscle HR.