[³H]ouabain binding and sodium content in lymphocyte sub-populations and the demonstration of increased binding in type 2 diabetes mellitus

Abstract

The number of specific [3H]ouabain binding sites in T-lymphocytes was determined and linear Scatchard plots were obtained. The number of sites was 30088 +/- 3039 (mean +/- SD) per lymphocyte in 14 healthy males and 33939 +/- 3185 in 11 males with type 2 diabetes (P less than 0.01). No difference between the dissociation constants were found (Kd = 3.91 and 3.86 mmol/l). The number of binding sites in lymphocytes from 15 healthy males with normal glucose tolerance but with a strong family history of type 2 diabetes did not differ from the controls. In T-lymphocytes a significantly higher number of specific ouabain binding sites was found than in non-T-lymphocytes (P less than 0.01). There was no difference between the dissociation constants. (Kd = 3.69 and 3.97 mmol/l). Intra-lymphocytic sodium was measured in 18 healthy individuals and the mean content was 8.1 +/- 2.3 mmol/kg lymphocytes. A lower content of sodium in T- compared to non-T-lymphocytes was also found (5.9 +/- 0.8 mmol/kg vs 15.5 +/- 0.8 mmol/kg, P less than 0.001). There was no correlation between lymphocytes and erythrocytes concerning [3H]ouabain binding sites or sodium concentration.

Necessity of Liver Biopsy for Accurate Diagnosis of Reye's Syndrome

“…A detailed questionnaire was answered by the parents of the obese children. We analyzed red cell Na-K-ATPase activity by the 3H-Oubain binding method, and measured intracellular N a + , K + and plasma Mg2+ and HPO~- (2,3).…”

Recessive inheritance of a high number of sodium pump sites

“…Hypertensive individ-uals have elevated levels of intracellular sodium [Hilton, 19861, probably owing to an abnormality in the sodium pump; Blaustein [ 19771 proposed a hypothesis relating sodium transport to blood pressure regulation. Berntorp et al [1985] found high sodium pump activity in diabetics, which may relate to stimulation of the sodium pump by insulin [Moore, 19831. The sodium pump consists of the enzyme Na' K' ATPase, which exchanges internal sodium for external potassium ions [Sweadner and Goldin, 19801. The sodium pump is selectively inhibited by ouabain, facilitating measurement of its activity.…”

Evidence for multiple genes determining sodium transport

“…However, obese subjects frequently do not exhibit reduced sodium pump activity [Ash et al, 1983;Beutler et al, 1983;Charalambous et al, 1984a;Miilunpalo et al, 1985;Simat et al, 1983;Webster et al, 19841, al-though the fault might lie in the inadequacy of erythrocytes as surrogates for highenergy-consuming cells [Charalambous et al, 1984b;Welle, 19891. Likewise, the sodium transport alterations reported for diabetic patients lack consistency [Bemtorp et al, 1985;Finotti and Palatini, 1986;Nagamatsu et al, 1986;Chimori et al, 19891. Of the three diseases, hypertension associates most consistently with sodium transport abnormalities [Rutherford et al, 19921. Garay [1990] lists five sodium transport abnormalities contributing to hypertension; the abnormalities include decreased affinity for internal sodium of the sodium-potassium pump and sodium-potassium cotransport and increased maximal rates of sodium-potassium cotransport, sodium-lithium countertransport, and passive sodium permeability.…”