Figure 2.

Effect of coexpressed XK-Ras2A^G12V on XENaC^F function and oocyte surface membrane area. (A) Amiloride-sensitive current (I_ami) was measured by the two-electrode voltage-clamp technique at a membrane potential of −100 mV in oocytes expressing XENaC^F, XENaC^F + XK-Ras2A^G12V, or XENaC^F in the presence of 15 μM progesterone. Progesterone-treated cells showed an approximately fourfold lower I_ami compared with control oocytes and XK-Ras2A^G12V–coinjected oocytes. (B) The membrane area of the oocytes (measured as capacitance) was decreased in maturing oocytes such that XK-Ras2A^G12V–coinjected oocytes had a higher I_ami per surface area than those of the two other groups (C). Results are expressed as means of five independent experiments ± SEM with each of four to nine oocytes per group.