title: Non-esterified fatty acids may regulate human leucocyte sodium pump activity.
abstract: Human leucocyte sodium pump activity was studied in normal fasting subjects by measuring the ouabain-sensitive 22Na+ efflux rate constants. This 22Na+ efflux rate constant was inversely related to the fasting plasma non-esterified fatty acid level (rs = -0.73, P less than 0.0001). An oral glucose load (40 g/m2 surface area) led to an increase in the leucocyte ouabain-sensitive 22Na+ efflux rate constant after 2 h (1.97 +/- 0.25 to 2.44 +/- 0.19 h-1, P less than 0.0001, n = 11). There was a concomitant fall in the plasma non-esterified fatty acid level. Incubation of leucocytes in vitro with 100 mumol/l linoleic acid inhibited the leucocyte ouabain-sensitive 22Na+ efflux rate constant (1.52 +/- 0.27 vs 0.84 +/- 0.24 h-1, P less than 0.001, n = 8). The leucocyte Na+,K+-dependent adenosine triphosphatase (Na+,K+-ATPase) activity was inhibited in vitro by long chain non-esterified fatty acids, especially when unsaturated. Non-esterified fatty acids may account for some of the Na+,K+-ATPase inhibitory activity of plasma.
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D008041:Linoleic Acids / Q000494:pharmacology; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D012964:Sodium / Q000097:blood*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000097:blood
chemical_list: D005230:Fatty Acids, Nonesterified; D008041:Linoleic Acids; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D005947:Glucose