Leong L. Ng1, T. D. R. Hockaday1
1Sheikh Rashid Diabetes Unit, Radcliffe Infirmary, Oxford, U.K.
Tóm tắt
1. Human leucocyte sodium pump activity was studied in normal fasting subjects by measuring the ouabain-sensitive 22Na+ efflux rate constants.
2. This 22Na+ efflux rate constant was inversely related to the fasting plasma non-esterified fatty acid level (rs = −0.73, P < 0.0001).
3. 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 < 0.0001, n = 11). There was a concomitant fall in the plasma non-esterified fatty acid level.
4. Incubation of leucocytes in vitro with 100 μmol/l linoleic acid inhibited the leucocyte ouabain-sensitive 22Na+ efflux rate constant (1.52 ± 0.27 vs 0.84 ± 0.24 h−1, P < 0.001, n = 8).
5. 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.
6. Non-esterified fatty acids may account for some of the Na+,K+-ATPase inhibitory activity of plasma.
