Hypertension, Vol 9, 437-443, Copyright © 1987 by American Heart Association
RE Ringel, JM Hamlyn, BP Hamilton, GA Pinkas, SA Chalew and MA Berman
Alterations of cellular function of Na+,K+-adenosine triphosphatase
(ATPase; Na+-K+ pump) have been implicated in the pathophysiology of
essential hypertension. Therefore, this aspect of red blood cell (RBC) Na
metabolism was studied in black men with newly diagnosed, untreated
essential hypertension (NEH) and a normotensive control group. RBC Na
content, Na+-K+ pump number (ouabain binding sites), and pump activity were
measured. No statistically significant differences were found between the
two groups for any of these three parameters. However, a group of
previously treated essential hypertensive subjects (PEH) who had been
withdrawn from therapy in the preceding 6 weeks were also studied. This
group differed significantly from the NEH subjects in regard to all RBC
Na+-K+ pump parameters. Their RBC Na content (10.27 +/- 3.23 vs 7.77 +/-
2.52 mmol Na/LRBC; p = 0.006) was higher, and their Na+-K+ pump activity
(166 +/- 50 vs 221 +/- 87 nmol inorganic phosphate/mg membrane protein/hr;
p = 0.03) and Na+-K+ pump number (213 +/- 40 vs 284 +/- 85 binding
sites/RBC; p = 0.001) were lower compared with those in NEH subjects.
Although the PEH subjects were older and somewhat less hypertensive than
their NEH counterparts, these factors were not found to influence the
Na+-K+ pump parameters. These results indicate that chronic diuretic
therapy of patients with essential hypertension is associated with a
reduced number of RBC Na+-K+ pumps. Since RBCs are not considered target
cells for diuretics, the effects of these drugs on RBC electrolyte
metabolism may occur at the time of erythropoiesis by the production of
RBCs with fewer Na+-K+ pumps.(ABSTRACT TRUNCATED AT 250 WORDS)
ARTICLES
Red blood cell Na+,K+-ATPase in men with newly diagnosed or previously treated essential hypertension