Erythrocyte cation transport is sex-related and is modified by oral contraceptives

Alterations in sodium metabolism as an etiological model for hypertension

An adequate matching for race, sex, stage of the menstrual cycle, family history of hypertension, and the amount of sodium and other electrolytes in the diet should be a prerequisite for valid conclusions when interpreting the erythrocyte concentration and fluxes of sodium in essential hypertensive patients in comparison with normal subjects. Alterations in intracellular sodium concentration and transmembrane sodium transport systems as causes of essential hypertension are postulated. This review article describes how this abnormal sodium and calcium metabolism translates into increased systemic vascular resistance through altered vasoactive responses and/or vasculature structural changes.

Cation transport mediated by Na+,K(+)-adenosine triphosphatase in lymphoblastoma cells from patients with bipolar I disorder, their relatives, and unrelated control subjects

In an investigation of cation transport in bipolar affective disorder, we have measured parameters related to Na+,K(+)-adenosine triphosphatase, the enzyme that carries out active transport of sodium and potassium, in lymphoblastoid cells cultured from patients with bipolar affective disorder, age-matched nonaffected family relatives, and unrelated control subjects. Patients had lower ion transport per cell and per transport enzyme site than did related or unrelated control subjects. The rate of transport per cell appeared higher in nonaffected relatives of patients than in unrelated control subjects, though this difference did not reach significance. These data suggest that abnormally regulated ion transport may be associated with bipolar affective disorder independently of clinical state.

Effects of 17 alpha-ethinyl oestradiol in vitro on erythrocyte cation transport in men and women

The effects of 17 alpha-ethinyl oestradiol in vitro upon erythrocyte Na(+)-K+ cotransport were investigated in nine normal males and in eight normal females during the mid-follicular phase of the menstrual cycle. At a concentration of 10(-1) mmol/l, Na(+)-K+ cotransport was almost completely inhibited. At concentrations of 10(-12) to 10(-2) mmol/l, a minor concentration-related effect was observed in males but not females. In the same concentration range, there was a significant difference in Na(+)-K+ cotransport between sexes. Thus, erythrocyte Na+K+ cotransport is lower in females than males, probably due to chronic exposure of their erythrocytes to endogenous oestrogen.

The effects of oestradiol administration on blood pressure and erythrocyte Na+ influx in oophorectomized rats

The effects of oestrogen on blood pressure and erythrocyte Na+ influx were measured in oophorectomized rats treated with oestradiol benzoate (100ug/kg/week i.m.) or vehicle for eight weeks. A significant increase in mean blood pressure was observed in the oestradiol-treated compared to the vehicle-treated group, together with a significant increase in red cell [Na+]. Oestradiol administration produced no significant changes in total Na+ influx, cotransport, countertransport or Na+ diffusion and did not alter plasma [Na+], red cell [K+], mean corpuscular haemoglobin concentration (MCHC) or blood volume per 100g body weight. However, significant decreases in body weight, haematocrit and plasma [K+] were observed in the oestradiol-treated group. These results support previous observations that oestradiol increases blood pressure and suggest that chronic administration of oestrogen increases red cell [Na+], probably by a mechanism other than alteration in erythrocyte passive Na+ transport.

Sodium pump parameters of red blood cells in men, women and women taking oral contraceptives

Three parameters of the sodium pump, the sodium efflux rate, the intracellular sodium content (Nai) and the number of sodium, potassium ATPase sites per red blood cell (sites/rbc) were measured simultaneously on erythrocytes from normal men and women and from women taking oral contraceptives. Significant (p less than 0.002) differences were obtained between normal men and women for sodium efflux (1.68 +/- 0.15 vs 1.52 +/- 0.12 mmoles/L rbc/hr). Among the three measured parameters, there was an inverse relationship (r = -0.74) between Nai and sites/rbc and a linear correlation (r = 0.89) between efflux per site and Nai. A positive correlation (r = 0.78) between the sites/rbc and a first-order rate constant for Na efflux/rbc suggests that one component of the rate constant is the number of sites/rbc. Values for a second-order rate constant, calculated from the assumption that efflux/rbc depends on both Nai and the number of sites/rbc, were similar for normal men and women but significantly (p less than 0.001) higher for women taking oral contraceptives.