[Voltage-dependent effects of lidocaine and its metabolite, monoethylglycine xylidide (MEGX), on maximum rate of rise (Vmax) of action potential upstroke in guinea-pig papillary muscles].
We studied the effects of lidocaine and MEGX on the sodium current, using Vmax as an indicator, at an extracellular potassium concentration ([K]o) of 10 mmol.l-1, and compared the present results with those obtained at 5.4 mmol.l-1 [K]o in our previous study. At 10 mmol.l-1 [K]o, both lidocaine (10 micrograms.ml-1) and MEGX (10 micrograms.ml-1) significantly decreased the Vmax at the steady-state of 1 Hz, caused a significant rate-dependent decrease in Vmax, and slowed the recovery kinetics of Vmax. These effects of both agents were more prominent than those obtained at 5.4 mmol.l-1 [K]o, suggesting that MEGX as well as lidocaine produce voltage-or [K]o-dependent blocking effects on Vmax.
Hiraoka
I
I
Department of Anesthesiology-Resuscitology, University School of Medicine, Ube.
Oshita
S
S
Itoh
M
M
Sakabe
T
T
Ban
T
T
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D008297:Male; D010210:Papillary Muscles / Q000187:drug effects* / Q000502:physiology
D008012:Lidocaine; C001173:monoethylglycinexylidide