A Circulating Inhibitor of the Platelet Na +,K + Adenosine Triphosphatase Enzyme (ATPase) in Patients With Allergic Diseases*

Abstract

ABSTRACT

Previous studies have documented the presence of a sodium-potassium-stimulated adenosine triphosphatase enzyme (Na⁺,K⁺ ATPase) inhibitor bound to platelet membranes and in the plasma of adult allergic subjects. Evidence was presented that freezing caused displacement of the inhibitor from the enzyme of platelet membranes. The purpose of this study was to determine whether pediatric subjects with allergic diseases also manifest a circulating and cell-bound Na⁺,K⁺ ATPase enzyme inhibitor. The Na⁺,K⁺ ATPase activity of a particulate fraction of sonicated platelets was determined by spectrophotometry in children with and without allergic diseases. The Na⁺,K⁺ ATPase activity (mean nmoles/μg protein/ min ± STD) of allergies (1.3 ± 1.6) was lower than that of controls (4.0 ± 2.0). In contrast, when the same platelet fractions were frozen prior to assay, Na⁺,K⁺ ATPase was higher in allergies (5.0 ± 2.3) than in controls (1.5 ± 0.7). Plasma collected from these same subjects inhibited purified canine kidney Na⁺,K⁺ ATPase activity (51.7% ± 12.9% inhibition for the allergic compared to 23.8% ± 15.4% for the control group). These data show that children with allergic diseases, like adults with allergy, have a circulating and platelet-bound inhibitor of the Na⁺,K⁺ ATPase enzyme. In vivo Na⁺,K⁺ ATPase inhibition in allergy could have profound effects on intracellular cation concentrations and broad implications for the pathogenesis of allergic diseases.