Effects of tocainide on normal and myotonic mammalian skeletal muscle.
The effects of the lidocaine derivative 2-amino-2',6'-propionoxylidide hydrochloride (tocainide, W-36095) on the contraction force and on membrane resting and action potentials of rat diaphragm were tested in vitro. In a concentration of 5 x 10(-4) mol/l, tocainide reduced the amplitude of the twitch by about 25% within 15 min. This reduction was reversible on washout of the drug. Tocainide had little effect on the membrane resting potential, but considerably affected the action potential: rate of rise, maximum amplitude and rate of fall were reduced, the duration increased. The conduction velocity of the action potential was reduced by 20%. Experimental myotonia produced in excised diaphragms or in anesthetized whole animals by anthracene-9-carboxylic acid was completely abolished by low doses of tocainide.
D000200:Action Potentials / Q000187:drug effects; D000813:Anilides / Q000494:pharmacology*; D000818:Animals; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects*; D009222:Myotonia / Q000503:physiopathology*; D051381:Rats
D000813:Anilides