Fig. 1.
Channel-active agents studied. Shown are the following: verapamil, 1 (R1 = H, R2 = OCH3); N-methylverapamil, 1q (R1 = CH3, R2 = OCH3); devapamil, 2 (D888; R1 = R2 = H); N-methyldevapamil, 2q (R1 = CH3, R2 = H). OTs represents the p-toluenesulfonate counterion dosed with the synthetic compounds, which will exchange with buffer anions. C1 is a synthetic control substance, (diethyldimethyl)ammonium tosylate, which has in common with the active agents the quaternary ammonium center and the tosylate counterion.