Key result
Bepridil markedly reduced sinus node automaticity, while lidocaine and l-chlorpheniramine depressed the action potential upstroke and prolonged its duration in rabbit pacemaker cells.
Bepridil, lidocaine, and l-chlorpheniramine exert distinct electrophysiological effects on rabbit sinus node pacemaker cells, with bepridil uniquely causing a marked reduction in automaticity.
Answers are grounded in this paper and cite their sources.
Supports mechanistic differentiation of antiarrhythmic effects in sinus node; leaves open translation to human therapy.
We compared the electrophysiological effects of lidocaine, l-chlorpheniramine, and bepridil on rabbit sinus node pacemaker cells. Only bepridil (0.25-2.0 mg/L) caused a marked reduction in the automaticity of the sinus node. Action potential amplitude, overshoot, and maximum rate of depolarization of phase O (MRD) were all reduced in a dose-dependent manner by bepridil. Decreases in maximum diastolic potential (MDP) and take-off potential were also observed, the former falling to approximately -40 mV when automaticity ceased. On the other hand, lidocaine (12-48 mg/L) depressed the upstroke of the action potential without significantly affecting MDP or take-off potential. The action potential duration was also prolonged at these concentrations. Both MDP and take-off potential were markedly reduced by l-chlorpheniramine (2.9-11.6 mg/L) and these changes were accompanied by reductions in amplitude, overshoot, and MRD of the action potential. A prolongation of the action potential duration was also observed. Pacing the sinus node preparations at a frequency of 4.5 Hz depressed the upstroke of the action potential and led to postoverdrive suppression. l-Chlorpheniramine abolished the postoverdrive suppression, whereas in the presence of lidocaine and bepridil a marked reduction and alternation in action potential amplitude occurred on pacing which made the accurate assessment of sinus node recovery time impossible.
No takes yet. Share an insight, caveat, or question.
Kane et al. (1983) studied Rabbit sinus node pacemaker cells. Lidocaine, l-chlorpheniramine, and bepridil was evaluated on Electrophysiological effects on sinus node automaticity and action potential. Bepridil markedly reduced sinus node automaticity, while lidocaine and l-chlorpheniramine depressed the action potential upstroke and prolonged its duration in rabbit pacemaker cells.
Synapse has enriched 10 related papers. Consider them for comparative context: