Evaluation of activation kinetics of macroscopic BK currents did not reveal significant differences between fetal and maternal membrane patches.

A. Original records showing macroscopic BK currents obtained from excised membrane patches from fetal and maternal cerebral artery myocytes. Currents were evoked by a series of 200 ms-long voltage steps of 10 mV from -150 to 150 mV (Vholding = -80 mV). [Ca2+]free = 3 μM. Vertical dashed lines define recording intervals at which macroscopic currents were fitted by a single-term exponential function to define τof activation. B. Averaged data reflecting activation kinetics (τact) in fetal and maternal myocyte membrane patches. C. Averaged G/Gmax-V curves from maternal and fetal artery myocyte patches. Here and in D, each averaged data point was obtained from 5 patches from fetal cerebral artery myocytes and 4 patches from maternal cerebral artery myocytes. Each patch was obtained from a different myocyte. D. Averaged Vhalf (voltage that is needed to reach half-maximal current) obtained from individual fits of G/Gmax-V data from fetal and maternal artery myocytes (P = 0.9999).