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Effects of magnesium, ouabain and bumetanide on 86 rubidium uptake in a human atrial cell line
Author(s) -
Borchgrevink P.C.,
Ryan M.P.
Publication year - 1988
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1988.tb11683.x
Subject(s) - bumetanide , ouabain , rubidium , magnesium , chemistry , line (geometry) , medicine , endocrinology , potassium , sodium , cotransporter , organic chemistry , geometry , mathematics
1 The effects of extracellular magnesium concentrations (0, 0.6, 1.2 m m ) on 86 Rb (used as an analogue of potassium) uptake were investigated in the Girardi human atrial cell line in the presence and absence of drugs. 2 Increasing extracellular magnesium resulted in significantly higher 86 Rb uptake. Compared to uptake in 0.6 m m (the physiological extracellular magnesium concentration), uptake of 86 Rb was significantly higher in the 1.2 m m magnesium medium and significantly lower in the magnesium‐free medium. 3 Ouabain (10 −3 m ) and bumetanide (10 −4 m ) were added to inhibit, respectively, the Na‐K‐ATPase and the Na‐K‐Cl co‐transport system in the media containing the three magnesium concentrations. The ouabain‐sensitive, bumetanide‐sensitive and residual transport were found to be 58%, 29% and 13% of the total uptake in the medium containing 0.6 m m magnesium. 4 The oubain‐sensitive 86 Rb uptake was inhibited significantly by reducing the magnesium concentrations to zero whereas the bumetanide‐sensitive and residual uptake were not significantly affected by different magnesium concentrations. 5 At three different ouabain concentrations (10 −7 m , 10 −5 m , 10 −3 m ) studied there was significantly greater uptake of 86 Rb in 1.2 m m magnesium compared to uptake in 0 m m magnesium. 6 The present findings indicate that extracellular magnesium is important for 86 Rb (potassium) transport in cardiac cells, and suggest that the main effect is on the Na‐K‐ATPase component of transport.