[Transmembrane effects in the sodium pump system. I. The effect of external potassium and rubidium on the dependence of sodium efflux on sodium concentration in the frog muscle].
The dependence of sodium efflux on intracellular sodium content with various potassium and rubidium concentration in the external medium has been studied on frog sartorious muscle. In potassium-sodium-free magnesium medium ouabain-sensitive sodium efflux was shown to be proportional to internal sodium concentration. In the presence of external ribidium (0.5--5.0 mM) the efflux concentration relations are non-linear, being closely described by assuming that 3 Na+ are transported per pump cycle. In sodium loaded muscles the efflux concentration curve was found to be dependent on the external rubidium concentration, becoming linear instead of S-shaped with the decrease in internal rubidium concentration from 5.0--2.5 to 1.0--0.5 mM. The apparent affinity constant for the internal sodium pump site increased with increasing the external rubidium (potassium) concentration. The data obtained may contribute to the kinetic evaluation of the type of Na-K pump mechanism, being more consistent with simultaneous model of pump operation.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology*; D011896:Rana temporaria; D012413:Rubidium / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*
D007473:Ion Channels; D012964:Sodium; D012413:Rubidium; D011188:Potassium
Transmembrannye éffekty v sisteme natrievogo nasosa. I. Vliianie naruzhnogo kaliia i rubidiia na zavisimost' vykhodnogo potoka natriia ot kontsentratsii natriia v myshtse liagushki.