Erythrocyte ion transport altered in hypertensive African–Americans with dyslipidemia
MedWire News: African–Americans with essential hypertension and dyslipidemia have decreased erythrocyte ion transport compared with Caucasians, a study suggests.
Researchers found that sodium, potassium, and chloride ion co-transport (NKCC1) activity in African–Americans was half of that seen in French Canadians, although this did not appear to be caused by an altered lipid profile.
The team suggests that decreased NKCC1 activity may contribute to the pathogenesis of salt-sensitive hypertension in African–Americans.
Recent studies demonstrate a key role for NKCC1 in regulation of myogenic tone and peripheral resistance, say Sergei Orlov (Centre hospitalier de l’Université de Montréal, Canada) and colleagues.
They examined its activity in 111 French-Canadian men, 107 French–Canadian women, 26 African–American men, and 45 African–American women with hypertension and dyslipidemia.
NKCC1 ion transport in African–American men was half that of their French–Canadian counterparts, at 191 versus 381 µmol/liter of cells/hour. For African–American women the reduction was 38% compared with French–Canadian women, at 176 versus 285 µmol/liter of cells/hour.
These differences were not accompanied by alternations in passive erythrocyte membrane permeability for potassium ions.
African–American men and women were 7 years younger on average than French Canadians, and had similar body mass index, total cholesterol, and low- and high-density lipoprotein.
However, plasma triglycerides were significantly lower in African–American men and women than in their French–Canadian counterparts.
Nonetheless, plasma triglycerides correlated positively with the NKCC activity only in French–Canadian men, which the researchers say argues against differences in activity being due to altered plasma lipids affecting ion fluxes across erythrocyte membranes.
Writing in the American Journal of Hypertension, they propose that “decreased NKCC1 contributes to attenuated myogenic tone that, in turn, leads to high blood pressure-induced kidney damage and approximately four-fold greater prevalence of end-stage renal disease documented in hypertensive African–Americans compared to their Caucasian counterparts”.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Anita Wilkinson