Fig. 4.
Representative traces of single action potentials showing the steady-state effects of 10K and then with elevated [Ca2+]o (1.3 to 10 mM) in surface fibers of soleus muscles. Action potentials were elicited with single 0.3-ms pulses using fine platinum electrodes. Exposure time in each solution was 4K (220 min), 10K (73 min), 10K + 10Ca (93 min), and 4K recovery (43 min). Horizontal dashed line represents 0 mV. The deflection before the upstroke of each action potential is the stimulus artifact.