Dissociation of Calcium Transients and Force Development following a Change in Stimulation Frequency in Isolated Rabbit Myocardium

Figure 2

Kinetic tracings from muscles stimulated from 1 Hz to 4 Hz (). Developed force () increases rapidly and then gradually following an increase in pacing frequency. The switch in frequency is marked by a rapid decline in at approximately 60 seconds. Time to peak tension (TTP) and time to 50% relaxation (RT₅₀) rapidly decline following an increase from 1 to 4 Hz pacing frequency and stabilize within 20 seconds of the frequency change.