ERYTHROCYTE NA-LI+ COUNTERTRANSPORT IN ESSENTIAL-HYPERTENSION - CORRELATION WITH MEMBRANE-LIPIDS LEVELS()

Objective To examine whether Na+-Li+ countertransport (SLC) activity i s linked to erythrocyte membrane lipid content. Design An observationa l case-control study. The maximal efflux rate of SLC, plasma cholester ol, triglycerides, phospholipids, low- and high-density lipoprotein ch olesterol levels and the erythrocyte membrane cholesterol, phospholipi ds and fatty acids contents were determined both in fasting normolipae mic normotensive subjects and in hypertensive patients. Methods The Li +-stimulated Na+ efflux was measured in Li+-preloaded erythrocytes, Me mbrane cholesterol and phospholipids levels were determined by the lat roscan technique. Membrane fatty acids were identificated by gas chrom atography, Several derived indices were also obtained. Results Erythro cyte membranes of hypertensive patients showed an increase in choleste rol:phospholipid ratio and a decrease in the total amount of polyunsat urated fatty acids, mainly at the expense of arachidonic acid and doco satetraenoic acid. SLC activity was higher in hypertensive patients an d correlated positively with the plasma triglycerides level and negati vely with the ratio of C20:4 to C20:3. Conclusion Our data from untrea ted normolipaemic hypertensive patients show that a higher SLC activit y was accompained by parameters that indicate a lower membrane fluidit y.