Figure 4.
Heme and hemin inhibit BKCa channels in inside-out membrane patches from cerebral artery smooth muscle cells. Bath (ie, intracellular) free [Ca2+] was 10 μmol/L. A, Original recordings at a membrane potential of +40 mV illustrating concentration-dependent BKCa channel inhibition by hemin. B, Concentration-dependent BKCa channel inhibition by hemin at +40 mV. Solid line illustrates Boltzmann fit to the data; n=1, 3, 6, 4, 5, 3, and 11 for 100 pmol/L, 300 pmol/L, 1 nmol/L, 3 nmol/L, 10 nmol/L, 30 nmol/L, and 100 nmol/L, respectively. C, Hemin inhibits BKCa channels at −40 mV. *P<0.05 compared with control.