FIGURE 3.

Dose response for inhibition of PESAC by furosemide. (A) Transmittance measurements with 0, 2, 12, and 200 μM furosemide added to the sorbitol lysis solution. Notice that the lysis time course is slowed by furosemide, but that the transmittance endpoint is not affected. (B) Calculated permeability as a function of furosemide concentration. For each furosemide concentration, P_S was calculated from transmittance and hemoglobin release experiments with Eq. 10 and then normalized with that of a control experiment (no added furosemide), performed simultaneously. The solid line represents a least-squares fit to the Hill equation, y = 1/(1 + (x/K_d)^∧L). A fit to the Michaelis-Menten equation produced a K_m of 2.7 μM and was essentially indistinguishable (not shown).