Sibling resemblance of erythrocyte ion transporters in French-Canadian sibling-pairs affected with essential hypertension

Objectives Erythrocyte Na+/Li+ countertransport and Na+,K+ cotransport are increased in some Caucasians with essential hypertension. This study examin es the relative contributions of genetic and shared environmental factors t o the activity of these ion carriers in French-Canadian sibling-pairs affec ted with essential hypertension. Design The activity of Na+/Li+ countertransport and Na+,K+ cotransport (rat e of Na-o(+)-dependent Li+ efflux and bumetanide-sensitive Rb-86 influx, re spectively) was measured in 122 French-Canadian siblings with essential hyp ertension, 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. Results Na+/Li+ countertransport and Na+,K+ cotransport were respectively h igher by 27% (P = 0.002) and 42% (P = 0.0009) in erythrocytes from men comp ared with women. Intra-individual correlation analysis did not reveal a sig nificant effect of age on the activity of these ion transporters in both ma les and females, and an influence of plasma lipids (triglycerides, choleste rol, low-density lipoprotein, high-density lipoprotein) in females. In male s, Na+,K+ cotransport was correlated with the level of serum triglycerides only (P = 0.01). Familial correlation analysis showed that sibling resembla nce 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). Conclusion The present data indicate that different factors contribute to t he 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 determ ined by inheritable factors in men than in women, J Hypertens 1999, 17:1859 -1865 (C) Lippincott Williams & Wilkins.