Figure 4. Volume changes of a NIS-expressing oocyte during isosmotic exposure to SCN⁻.

The oocyte was clamped to −70 mV and 0.2 mm of NaSCN replaced NaCl at time zero. This initiated an increase in relative oocyte volume (ΔV_T/V_T) and an inward clamp current I_C, which rose with a time constant of about 2 s. A close approximation of CR was derived from the initial 40 s of volume changes and the integrated I_C. The experiment was simulated with CR = 315, D_i= 0.3 × 10⁻⁵ cm² s⁻¹ and V_F/V_T= 0.28 (thin line). L_p= 0.33 × 10⁻⁵ cm s⁻¹ (osmol l⁻¹)⁻¹ and r= 0.062 cm were measured separately. Washout of SCN⁻ began at 50 s.