[Biphasic changes in isometric tension after a temperature jump in skinned Ca-activated skeletal muscles of the frog].

Joulean temperature jump from 4--7 degrees to 10--25 degrees C completed in 0.2 ms induced biphasic rise of tension in suspended in the air segments of chemically skinned Ca-activated (pCa = 5.5 divided by 6) muscle fibres of the frog. Amplitudes of the 1st and 2nd phases grew up to 30--40% and 60--70% of the initial tension correspondingly when the amplitude of temperature jump increased to 17--21 degrees C. The time constant of the 1st phase (1.3--0.5 ms) decreased with temperature (Q10 = 1.8). The time constant of the 2nd phase was about 10 ms.