Race, sex, and family history of hypertension and erythrocyte sodium pump [3H]ouabain binding.

Abstract

We studied the binding properties of [ 3 H]ouabain to erythrocytes from normotensive children (n=83) between the ages of 10 and 18 years (mean resting arterial pressure: 102/57 mm Hg) from normotensive and essential hypertensive parents. Arterial blood pressures of 101/57 and 104/57 mm Hg (subjects with normotensive and hypertensive parents, respectively) were not significantly different between the two groups. Forty-four children had normotensive parents and 39 had hypertensive parents, 51 were white and 32 were black, and 41 were girls and 42 were boys. By using the [ 3 H]ouabain-binding technique, we determined the density of sodium pump sites and the equilibrium dissociation constants in erythrocytes from these children. Possible effects of race, sex, or parental hypertension status on pump sites and dissociation constants were tested with a three-way analysis of variance (ANOVA). Race had a major effect on the dissociation constant: blacks had a significantly higher value than did whites (p=0.002). We also found a race by sex by parental hypertension status interaction (p=0.04) with black girls with hypertensive parents having the highest value. There was no effect of race, sex, or status on sodium pump site density. Age, height, weight, resting arterial blood pressure, and plasma Na + and K + concentrations did not correlate with the dissociation constants. These data suggest that, among the groups we studied, black girls with hypertensive parents had erythrocytes with the lowest binding affinity for ouabain. In addition, race had a strong effect on the binding affinity of ouabain to human erythrocytes, with blacks having lower affinities than whites. Because the black population has a much higher prevalence of hypertension than the white population and black women have the highest prevalence of hypertension, this decrease in the affinity of ouabain-binding to the erythrocyte sodium pump molecule may be a possible predictor of adult hypertension. (Hypertension 1990;15:146- Parts of this study were presented at the 60th Scientific Sessions of the American Heart Association in Anaheim, California, November 16-19, 1987. Supported by research grants HL-35788 and HL-32270 from the National Institutes of Health and a Grant-in-Aid from the American Heart Association, Tennessee Affiliate.Address for correspondence: Dr. Emel Songu-Mize, Department of Pharmacology, University of Tennessee, Memphis, 874 Union Ave., Rm 100, Memphis, TN 38163.Received September 20,1988; accepted in revised form October 13, 1989. transport pathways in other tissues, such as the vasculature, have also been noted in some animal models of hypertension. 13- 16 In some reports, normotensive offspring of hypertensive individuals manifested some of these sodium transport abnormalities. -1718 In spite of extensive knowledge related to cation transport in hypertensive persons, findings related to ouabain-sensitive or the sodium pumpdriven transport system are less definitive than findings for other transport systems. Moreover, binding prop...

Salt sensitivity in hypertension. Renal and cardiovascular implications.

“…172 Dichtchekenian et al 173 observed higher serum levels of digoxin-like factor in salt-sensitive than salt-resistant patients with hypertension and a significant correlation of those levels with blood pressure; however, a high NaCl diet failed to increase the serum levels of the digoxin-like factor in both groups of patients. Songu-Mize et al 174 showed very low binding affinity for ouabain in erythrocytes from black girls with hypertensive parents.…”

“…Some researchers have shown a decrease 174 and others an increase 176 in the V nai of the Na + -K + cotransport system. Some have shown a direct relation between severity of hypertension, decrease in venous compliance, and the Kna, of the Na + -K + cotransport.…”

Ethnicity, pressor reactivity, and children's blood pressure. Five years of observations.

“…A third consideration is the small number of potential predictors of BP that were examined. Though constrained by finances, personnel, and the need to perform examinations expeditiousry, the measurement of additional variables, e.g., cation transport 45 or socioeconomic status, 46 might have altered the results. Despite these limitations, the data were consistent: black children demonstrated greater pressor reactivity than white children at every examination, and pressor reactivity was more strongly associated in blacks than whites with future BP.…”

Lower extremity vascular injuries: Increased mortality for minorities and the uninsured?

“…13,14 Some researchers have found genetic differences between races for particular disease states, such as diabetes 15-17 and hypertension. 18,19 Still other investigators have found that outcome disparities for the uninsured, Medicaid patients, and people of color are at least partially attributable to differences in baseline health characteristics and hospital performance. 20,21 …”