Figure 4. Voltage-gated inward currents occur in schistosome muscle fibers, but they rapidly rundown.

(A) An inward current is evoked by a 200 ms depolarizing step to +20 mV from a holding potential of -70 mV in the presence of 2 mM extracellular Ca²⁺ and 15 mM extracellular Ba²⁺. The dashed line represents the baseline current level, the horizontal bars show the times from which the peak and sustained current values were derived, and the vertical scale bar is 20 pA. (B) The inward current runs down with time. On average, currents reached peak amplitude 1.5 minutes after the start of the trial and maintained an approximate steady level for the next 3-6 min followed by steady decline in amplitude. This graph shows that peak and sustained current amplitudes for the same muscle fiber depicted in (A).