A. The typical recordings show that IK, evoked by voltage step to +50 mV, was increased from 4.57 nA to 6.38 nA when the external solution was changed from 300mOsm to 220mOsm for 3min and the current recovered to 4.77 nA after washout. B. The peak current-voltage relationship (I–V) was shown before and during hypotonicity treatment. C. In the presence of hypotonicity, G–V curve did not shift significantly. V0.5 was −0.93±1.30 mV and −0.90±0.71 mV (n=8, paired t test, P>0.05) for 300mOsm and 220mOsm, respectively; k was 16.46±1.13 and 16.07±0.41 (n=8, paired t test, P>0.05), respectively. Data were transformed from the I–V data shown in B. D. The typical recordings show that hypotonicity increased IK and inactivation–voltage curve significantly shifted to depolarizing direction. V0.5 was −72.67±1.54 mV and −40.55±5.25 mV (n=8, paired t test, P<0.05) for 300mOsm and 220mOsm, respectively; k was −9.67±1.32 and −10.98±4.61 (n=8, paired t test, P>0.05), respectively.