Erythrocyte Na+/Li+ countertransport and Na+,K+ cotransport are increased in some Caucasians with essential hypertension. This study examines the relative contributions of genetic and shared environmental factors to the activity of these ion carriers in French–Canadian sibling-pairs affected with essential hypertension.
The activity of Na+/Li+ countertransport and Na+,K+ cotransport (rate of Na+o-dependent Li+ efflux and bumetanide-sensitive 86Rb influx, respectively) was measured in 122 French-Canadian siblings with essential hypertension, including 36 brother/brother and 48 sister/sister pairs. Sibling/sibling correlations were estimated using the FCOR program of the S.A.G.E. package.
Na+/Li+ countertransport and Na+,K+ cotransport were respectively higher by 27% (P = 0.002) and 42% (P = 0.0009) in erythrocytes from men compared with women. Intra-individual correlation analysis did not reveal a significant effect of age on the activity of these ion transporters in both males and females, and an influence of plasma lipids (triglycerides, cholesterol, low-density lipoprotein, high-density lipoprotein) in females. In males, Na+,K+ cotransport was correlated with the level of serum triglycerides only (P = 0.01). Familial correlation analysis showed that sibling resemblance of Na+/Li+ countertransport and Na+,K+ cotransport was higher in men (r = 0.26 and 0.39) than in women (r = 0.01 and 0.03, respectively).
The present data indicate that different factors contribute to the regulation of monovalent ion carriers in erythrocytes from Caucasian men and women with essential hypertension. The activity of erythrocyte Na+/Li+ countertransport and Na+,K+ cotransport appears to be more strongly determined by inheritable factors in men than in women.