The effects of local anaesthetics on the isometric contraction of the isolated hemidiaphragm of the rat.
Local anaesthetics (benzocaine, tetracacine, lidocaine, cocaine, procaine) were found to depress both Td and dT/dt max of the isometric contraction of the isolated hemidiaphragm of the rat during direct electrical stimulation. The same substances were found to antagonize the action of aminophylline on Td and dT/dt max of the isolated hemidiaphragm during direct stimulation. The effect of higher concentrations of aminophylline was even reversed by cocaine, procaine and lidocaine. Increasing of calcium concentrations did not reverse the antagonistic action of aminophylline on Td and dT/dt max of the isometric contraction of the isolated hemidiaphragm. It is suggested that a change in the muscle membrane is responsible for the observed action of local anaesthetics on Td and dT/dt max, as well as for their antagonistic action towards aminophylline.
D000628:Aminophylline / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003964:Diaphragm / Q000187:drug effects; D004347:Drug Interactions; D004558:Electric Stimulation; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D051381:Rats; D013997:Time Factors
D000779:Anesthetics, Local; D000628:Aminophylline; D002118:Calcium