Reversible stimulation of the Na+/K+ pump by monensin in cultures of vascular smooth muscle.
Two ionophores, monensin and salinomycin, increased total cell Na+ and ouabain-sensitive 86Rb+ uptake in cultures of smooth muscle cells from rat aorta. Monensin was used to produce graded increases in cell Na+ in order to assess the Na+ dependence of the Na+/K+ pump in the intact cell. The relationship between internal Na+ and ouabain-sensitive 86Rb+ uptake was hyperbolic (K'Na = 3 mM). Monensin did not stimulate 86Rb+ uptake in the absence of external Na+. Loading the cells with Na+ by exposing cultures to a K+-free medium for 3 hr maximally increased cell Na+ and ouabain-sensitive 86Rb+ uptake to the same extent as monensin. Total cell Na+ and pump activity in monensin-treated cells returned to the initial values after removing the ionophore. Monensin was then able to increase total cell Na+ and ouabain-sensitive 86Rb+ uptake to the same extent as the initial treatment with the ionophore.
D000818:Animals; D001011:Aorta / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D002478:Cells, Cultured; D005663:Furans / Q000494:pharmacology*; D007476:Ionophores / Q000494:pharmacology; D008757:Methylglucosides / Q000378:metabolism; D008985:Monensin / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D011714:Pyrans / Q000494:pharmacology; D051381:Rats; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000095662:Polyether Polyketides
D005663:Furans; D007476:Ionophores; D008757:Methylglucosides; D008985:Monensin; D011188:Potassium; D011714:Pyrans; D012413:Rubidium; D012964:Sodium; C010327:salinomycin; D000095662:Polyether Polyketides