title: On the mechanism of catecholamine-induced hyperpolarization of skeletal muscle cells.
abstract: Catecholamines (noradrenaline, adrenaline and isoprenaline) were tested for their effect on the resting membrane potential of mouse skeletal muscle cells. In freshly isolated muscles incubated in the normal solution containing 5 mol . l-1, catecholamines increased the resting membrane potential (RMP) by 3-5 mV. In Na+-loaded muscles incubated in a K+-free solution, however, catecholamines increased the RMP by 13-16 mV; consequent application of K+ to these muscles did not hyperpolarize the membrane further. A significant decrease of input membrane resistance was observed during the noradrenaline-induced hyperpolarization. This indicates that the passive membrane permeability for K+ ions was apparently increased. Noradrenaline-induced hyperpolarization requires the presence of calcium ions in the incubation solution. We therefore assume that catecholamines hyperpolarize the membrane by Ca2+-dependent K+-channels activation. The action of catecholamines on the resting membrane potential of skeletal muscle exhibits a 50% nonspecific effect as far as the adrenergic receptor is concerned, and the rest may be blocked by adrenergic blocking agents.
authors.forename: H
authors.initials: H
authors.lastname: Zemková
authors.forename: P
authors.initials: P
authors.lastname: Svoboda
authors.forename: J
authors.initials: J
authors.lastname: Teisinger
authors.forename: F
authors.initials: F
authors.lastname: Vyskocil
mesh_terms: D000818:Animals; D002395:Catecholamines / Q000494:pharmacology*; D004837:Epinephrine / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects; D007545:Isoproterenol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D009132:Muscles / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013565:Sympatholytics / Q000494:pharmacology
chemical_list: D002395:Catecholamines; D007473:Ion Channels; D013565:Sympatholytics; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D007545:Isoproterenol; D011188:Potassium; D009638:Norepinephrine; D004837:Epinephrine