Comparison of the sensitivity of K⁺ efflux to DIOA and okadaic acid of red cells from transgenic mice expressing exclusively human hemoglobins. (A) Comparison under hypotonic conditions. We estimated K⁺ efflux into 250 mOsm hypotonic Cl^- media in red cells from HbAKO, HbSKO+γ, and HbCKO mice as described in “Materials and methods” in the presence or absence of 10 μM DIOA or 100 nM okadaic acid (OKA). The figure shows the average ± SE of 3 different experiments performed on at least 4 different mice per mouse type. (For hypotonic Cl^- HbSKO or hypotonic Cl^- HbCKO versus DIOA or OKA, P < .04). (B) Comparison under isotonic Cl^- at pH 7.0 conditions. We estimated K+ efflux into 330 mOsm isotonic pH 7.0 Cl^- media in red cells from HbAKO, HbSKO+γ, and HbCKO mice as described in “Materials and methods” in the presence or absence of 10 μM DIOA or 100 nM okadaic acid (OKA). The figure shows the average ± SE of 2 different experiments performed on at least 2 different mice per mouse type. (For isotonic pH 7.0 HbSKO or isotonic pH 7.0 HbCKO versus DIOA or OKA, P < .03).