Does lindane (gamma-hexachlorocyclohexane) increase the rapid delayed rectifier outward K+ current (IKr) in frog atrial myocytes?

Table 1 Effect of lindane on spontaneously beating frog atrial action potential (AP) AP was recorded using intracellular microelectrodes before and after successive and cumulative addition of lindane to the Ringer solution (control).

Treatments	RP (mV)	OS (mV)	APD₀ (ms)	APD₄₀ (ms)	APD₁₀ (ms)
control	-90.3 ± 2.0	24.3 ± 1.2	162 ± 9	450 ± 13	532 ± 13
lindane 0.34 microM	-90.0 ± 1.5	23.1 ± 1.3	157 ± 8	422 ± 5^*	514 ± 6^*
lindane 1.7 microM	-91.9 ± 1.1	26.9 ± 1.4	154 ± 8	420 ± 5	510 ± 5
lindane 3.4 microM	-91.8 ± 1.0	20.7 ± 1.3	128 ± 7⁺	424 ± 6	507 ± 5
lindane 6.8 microM	-92.7 ± 1.7	18.0 ± 1.7	111 ± 12	423 ± 7	501 ± 9

(RP) resting membrane potential; (OS) amplitude of the overshoot; (APD₀) duration of the AP measured at 0 mV; (APD₄₀) and (APD₁₀) duration of the AP measured at a membrane potential + 40 mV and + 10 mV higher than RP, respectively. The data are mean values ± s. e. mean of 12 AP recorded from 2 different atriums. P < 0.05: ^* lindane 0.34 microM versus control; ⁺ lindane 3.4 microM versus lindane 0.34 microM.