Figure 7.

Maximum enhancement in the amplitude of HF oscillations in HR (HF HR) or changes in STVQT in two groups of hERG blockers tested at various dose levels in beagle dogs. (A) All hERG blockers of group I enhanced HR HF oscillation amplitude. (B) In the second group (II), hERG blockers rather caused a reduction in endogenous HF oscillations in HR. (C) Only two hERG blockers of the group I (dofetilide and terfenadine) were found to cause statistically significant increases in STVQT. (D) Compounds in group II causing the largest reduction of HF oscillations also induced the largest decrease in STVQT. All drugs were given orally: CIS, cisapride; CIP, ciprofloxacin; DOF; dofetilide; EBA, ebastine; HAL, haloperidol; MOX, moxifloxacin; NIC, nicardipine; PHE, phenytoin; RIS, risperidone; SOT, DL sotalol; TER, terfenadine; THI, thioridazine; VER, verapamil. Figures close to abbreviations indicate tested dose levels in mg·kg⁻¹ p. o. Values were determined relative to vehicle at peak of effect. Data are presented as mean values ± SEM; n = 6 per compound. *P ≤ 0.05, **P ≤ 0.01, significantly different from vehicle.