title: Effects of sodium extrusion and local anaesthetics on muscle membrane resistance and potential.
abstract: 1. Membrane potentials and resistances of K-depleted muscles were measured in the cold and again after warming in K-containing media so that active ion movements occurred.2. On warming there was a fall of resistance and a gradual rise of potential which passed through a maximum. Later measurements of resistance in a chloride medium showed that values were, if anything, higher than initially in the warm.3. The excess potentials measured approximated to those required to induce passive inward movement of the K ions through the measured K resistance.4. Permeabilities for K(+) and Cl(-) were deduced. When cocaine, procaine, amytal or mepyramine were added or when K(+) was replaced by Rb(+) in the Cl(-)-free solution the K(+) permeability was eventually reduced. The same agents led to an enhanced initial response of potential to warming, but later the potentials in Cl(-)-free media fell to less than the K(+) equilibrium values.5. A method for obtaining the resistivity of the membrane from measurements made in conditions of non-linear voltage-current dependence was applied.
mesh_terms: D000654:Amobarbital / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D001001:Anura; D001692:Biological Transport; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002712:Chlorides / Q000378:metabolism; D003042:Cocaine / Q000494:pharmacology; D004594:Electrophysiology; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009132:Muscles / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*; D011343:Procaine / Q000494:pharmacology; D012413:Rubidium / Q000494:pharmacology; D012964:Sodium / Q000378:metabolism*
chemical_list: D000779:Anesthetics, Local; D002712:Chlorides; D006634:Histamine H1 Antagonists; D011343:Procaine; D012964:Sodium; D000654:Amobarbital; D003042:Cocaine; D012413:Rubidium; D011188:Potassium