title: [Effect of barium and ouabain on electrogenesis in various sites of intact and detubulated skeletal muscle fibers of the frog R. temporaria].
abstract: In loose patch clamp experiments on intact sartorious muscle fibers of the frog Rana temporaria there were revealed two types of wave forms of the extracellularly recorded action potentials (AP). Responses of the first type (T1AP) consisted of the initial positive phase with subsequent phase of strong negativity. Responses of the second type (T2AP) had an additional positive phase concluding their waveform. In the detubulated fibers, only T1AP were recorded. Application Ba2+ (10 microM) to the muscle led to a significant increase in the amplitude of the third T2AP phase, whereas the T1AP characteristics of both intact and detubulated muscle preparations remained unchanged. After the higher applied Ba2+ concentration (50 microM), in some of the studied intact fibers the late positive signal phase was replaced by the late negative phase. The amplitude of the late negative phase was increased markedly by the high-frequency stimulation. At the combined action of ouabain and Ba2+ there was summation of effects. These results can tentatively be explained by that the locally recorded T1AP and T2AP represent responses of the muscle fiber surface and T-tubular membranes and that caracteristics of the late phase of T2AP are determined by activities of T-tubular potassium channels and of Na, K-ATPase.
authors.forename: I V
authors.initials: IV
authors.lastname: Kubasov
authors.forename: M G
authors.initials: MG
authors.lastname: Dobretsov
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D001464:Barium / Q000008:administration & dosage; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000502:physiology; D010042:Ouabain / Q000008:administration & dosage; D018408:Patch-Clamp Techniques / Q000379:methods; D011896:Rana temporaria / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000502:physiology
chemical_list: D001464:Barium; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase