Differences in erythrocyte sodium transport between human plasma and artificial medium: the role and character of sodium efflux and influx stimulating plasma factors.

The main objective of this study was to further characterize the plasma factor(s) which stimulate sodium efflux from erythrocytes, which we reported previously. Dialysis of plasma against an artificial medium using membranes with varying molecular mass cut-off points revealed relative molecular mass(es) of the factor(s) of 100-1000 Da. The factor(s) could be absorbed on Dowex at pH 1.5 and Amberlite at pH 11.0, indicating 'Zwitterionic' character. They are hydrophilic and resistant to acid hydrolysis. These characteristics and direct measurements of contents made amino acids likely candidates for the efflux stimulating properties of the factor(s). Indeed, plasma amino acids added to artificial medium could abolish the sodium efflux difference between plasma and the artificial medium. The efflux stimulating effect of amino acids appeared not to be the result of sodium influx stimulation. A coincident finding was that plasma also contains dialyzable sodium influx stimulating factor(s) which are not amino acids.

Human plasma contains low molecular weight factors which stimulate active sodium transport in erythrocytes.

The aim of this study was to establish whether differences in sodium efflux rate constants (ke) in human erythrocytes occur when artificial media are compared with plasma. Using a 22Na tracer method, a mean total ke of 0.49 +/- 0.10 h-1 and significantly (p less than 0.05) lower ke values in Hanks' solution (0.43 +/- 0.08 h-1) and Basic Salt Solution (0.37 +/- 0.07 h-1) were observed. Exhaustive dialysis of plasma against Hanks' solution over a membrane with relative molecular mass cut-off of 1000 Da resulted in a decrease of the plasma total ke value to that measured in Hanks' solution. After equilibrium dialysis of plasma against Hanks' solution a decrease of total ke was found in plasma and an increase of the ke in Hanks' solution was measured. The data suggest the presence of an excess of dialyzable, active sodium transport stimulating plasma factor(s) with relative molecular mass below 1000 Da.

Sequential development of Waldenström's macroglobulinemia and gamma-1-heavy chain disease in a single patient. Clinical, immunochemical, immunofluorescent and protein studies.

The present paper deals with the rare phenomenon of the sequential development of Waldenström's macroglobulinemia (WM) and gamma 1-heavy chain disease (gamma 1-HCD) in a single patient. The coexistence of both monoclonal proteins lasted for more than 9 years. Serial determinations were made of serum levels of IgM, IgA, intact IgG, and the gamma-HCD protein. Immunofluorescent studies of a bone marrow aspirate confirmed the diagnosis of an IgM(kappa) monoclonal gammopathy and also showed cells which were thought to synthesize the gamma-HCD protein. The molecular weight of the gamma-HCD protein was 60,000 in the dimeric form. It is concluded that the original IgM(kappa) monoclonal gammopathy predisposed the patient for a second lymphoproliferative disorder (the gamma-HCD) and that both monoclonal proteins are immunogenetically unrelated.

Erythrocyte sodium-potassium co-transport in hypertension.

This paper reports on the measurement of sodium-potassium co-transport across red cell membranes in patients with hypertension and in normotensive volunteers. No differences were found in flux values between these two groups. Antihypertensive medication such as propranolol and enalapril (converting enzyme inhibitor) had no unequivocal effect on the measured cation transport. Individual diurnal and day-to-day variation of fluxes appear to be substantial. It is concluded that uniformity in the assay procedure may be of great importance before studying any difference in cation transport between various populations.