Quantifying antiarrhythmic drug blocking during action potentials in guinea-pig papillary muscle.

This report examines the blocking effects that several antiarrhythmic drugs have on rapid upstroke velocities of action potentials recorded from guinea-pig papillary muscle. A mathematical analysis is developed, that measures an effective "blocking rate' that acts during the action potential with the purpose being to compare these blocking rates for different drug structures. There is a systematic, inverse relationship observed between the concentration of amide-linked drug that must be applied in order to produce a given blocking effect and the lipid distribution capability of each drug. Ether-linked drug structures are relatively more potent than amide-linked drugs in this context.