Calcium-sensitive behavior of the current is confirmed in excised (inside-out) patches from freshly isolated cerebral artery myocytes of fetal baboon.

A. Original recordings of channel activity at different transmembrane voltages in I/O patches at 3 μM and 30 μM [Ca2+]free bathing of the intracellular side of the patch membrane. Arrows pointing to baseline indicate all channels closed. NPomax = maximal open probability detected for this membrane patch. Please note that current amplitude scale for +60 mV recording obtained at 3 μM [Ca2+]free differs from the scale for other records. B. Averaged NPo/NPomax-V curves show leftward shift of the current along the voltage axis at 30 μM when compared to 3 μM [Ca2+]free. Here and in C, each averaged data point was obtained from 3 patches at 30 μM (each patch obtained from a different fetus) and 14 patches at 3 μM [Ca2+]free (each patch was obtained from a different myocyte, no more than 5 patches were obtained from the artery of one fetus). C. Averaged Vhalf (voltage that is needed to reach half-maximal current) at 30 μM [Ca2+]free is significantly lower than Vhalf at 3 μM [Ca2+]free. **Statistically significant difference from 3 μM [Ca2+]free, P = 0.0001.