The subcellular location of potassium flux pathways in frog skeletal muscle.
The influence of ouabain and physostigmine on 42K and 86Rb uptake in isolated from sartorii with normal [Na]i(12-14 mmol.kg -1 wet weight) and low [Na]i (6 mmol.kg-1 wet weight) was compared. Both in normal sodium and in low sodium muscles application of 10-3 M physostigmine reduces potassium influx by about 70%. About one forth of potassium-uptake in normal-sodium muscles is inhibited by ouabain (10-4 M) and only a very slight fraction of potassium uptake is ouabain-sensitive in low-sodium muscle. The effects of ouabain and physostigmine on 42K influx are additive. The greater parts of the Rb-fluxes are through the ouabain-sensitive pathway. Glycerol treatment has no effect on ouabain-sensitive channels although it inhibits markedly the K-flux through the physostigmine-sensitive pathway. The results suggest that the Na-K-ATPase is located in the surface membrane while most of the physostigmine-sensitive K-exchange is within the tubules.
D000818:Animals; D005990:Glycerol / Q000494:pharmacology; D006982:Hypertonic Solutions; D007552:Isotonic Solutions / Q000494:pharmacology; D009132:Muscles / Q000378:metabolism* / Q000648:ultrastructure; D010042:Ouabain / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology; D011188:Potassium / Q000032:analysis / Q000378:metabolism*; D011868:Radioisotopes; D011893:Rana esculenta / Q000502:physiology; D000077331:Ringer's Solution; D012413:Rubidium; D012964:Sodium / Q000032:analysis / Q000494:pharmacology
D006982:Hypertonic Solutions; D007552:Isotonic Solutions; D011868:Radioisotopes; D010042:Ouabain; D000077331:Ringer's Solution; D012964:Sodium; D010830:Physostigmine; D012413:Rubidium; D005990:Glycerol; D011188:Potassium