Effects of natural polyamines on IKin. At −160 mV, the whole-cell current amplitudes in the presence of 1 mm tested compounds are shown as percentage of the control. CTL, control, n = 14; BUT, butylamine, n = 9; PUT, putrescine, n = 8; CAD, cadaverine, n = 9; SPD, spermidine, n = 18; SPM, spermine, n = 11. Asterisks indicate significant differences as compared with the control (P < 0.05).