The effect of diphenylamine-2-carboxylate on C1- channel conductance and on excitability characteristics of rat skeletal muscle.
The effect of diphenylamine-2-carboxylate (DPC), a blocker of the C1- conductive pathway in C1- transporting epithelia, has been evaluated in-vitro on the electrophysiological variables of rat extensor digitorum longus muscle fibres. DPC (5-240 microM) caused a dose-related increase of membrane resistance which was attributed entirely to a fall in C1- channel conductance (IC50, 120 microM), since potassium conductance was not affected by the treatment. DPC also modified fibre excitability. A significant dose-dependent increase was observed in the latency of the action potential and in the excitability of the membrane. DPC was less potent on striated fibres than anthracene-9-carboxylic acid, another specific blocker of C1- channel conductance. Moreover DPC was less potent on skeletal muscle than on C1- transporting epithelia. Morphological differences in the C1- channels or of the drug binding sites may account for the differences between tissues.
Camerino
D C
DC
Dept. of Pharmacobiology, Faculty of Pharmacy, University of Bari, Italy.
De Luca
A
A
Mambrini
M
M
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D062367:ortho-Aminobenzoates / Q000494:pharmacology*
D015220:Calcium Channels; D062367:ortho-Aminobenzoates; C001209:fenamic acid; D002118:Calcium