Three distinct components of the negative inotropic action of lidocaine in dog Purkinje fiber.
1. The negative inotropic action of 10 microM lidocaine and 100 microM nicorandil was compared as a function of the pacing cycle length, ranging from 300-3000 ms, in isolated canine Purkinje fiber preparations. 2. The applied concentrations of lidocaine and nicorandil produced similar shortening of action potential duration; however, lidocaine compromised contractility stronger than nicorandil at each cycle length. 3. Normalizing the inotropic action of the drugs to their shortening effect on action potential duration, the negative inotropic action of lidocaine can be regarded as a sum of three distinct components: negative inotropy associated to the shortening of action potential duration per se, reduction of contractility likely due to direct inhibition of the fast sodium current and of the "window" sodium current by lidocaine.
Pankucsi
C
C
Department of Physiology, University Medical School of Debrecen, Hungary.
Varró
A
A
Nánási
P P
PP
D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D008012:Lidocaine / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009536:Niacinamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D020108:Nicorandil; D011690:Purkinje Fibers / Q000187:drug effects*; D013268:Stimulation, Chemical
D000889:Anti-Arrhythmia Agents; D009536:Niacinamide; D020108:Nicorandil; D008012:Lidocaine