Figure 8.
Panel A shows a voltage-clamp protocol with two pulse patterns, where the membrane potential steps between minus 90 millivolts and minus 30 millivolts. Panel B displays superimposed cytosolic calcium concentration transients, with the vertical axis labeled in micromolar and a reference value of 1.5 micromolar. The horizontal axis spans 300 milliseconds. The traces show calcium responses elicited by the pulse patterns shown in Panel A. Panel C presents derived depletion-corrected calcium release flux, with the vertical axis labeled in millimeters per second and a reference value of 20 millimeters per second. The horizontal axis spans 300 milliseconds. The traces correspond to the pulse patterns in Panel A and illustrate suppression of calcium release during subsequent pulses despite differences in cytosolic calcium concentration.
Calcium transients and release flux activated by a train of pulses. (A–C) Superimposed cytosolic [Ca2+] transients (B) and derived depletion-corrected Ca2+ release flux (C) elicited by the two pulse patterns in A. The nearly complete (91%) suppression of release in the pulses that follow the first one is not altered in spite of the large variation in cytosolic [Ca2+]. Reproduced from Pizarro et al. (1997). Fig. 8 reprinted with permission from Journal of Physiology.