Research Article: Changes in erythrocyte ATPase activity under different pathological conditions

Date Published: December , 2017

Publisher: Makerere Medical School

Author(s): Ali A Kherd, Nawal Helmi, Khadijah Saeed Balamash, Taha A Kumosani, Shareefa A AL-Ghamdi, M Qari, Etimad A Huwait, Soonham S Yaghmoor, Alaama Nabil, Maryam A AL-Ghamdi, Said S Moselhy.

http://doi.org/10.4314/ahs.v17i4.31

Abstract

Studies have shown that Na+-K+ ATPase activity was altered in disrupted red blood cell membranes and this enzyme is believed to be the site of active transport of Na+ and K+ in intact red blood cells. The enzyme is often referred to as Na+-K+ pump because it pumps Na+ out and K+ into the cell against gradients with the concomitant hydrolysis of intracellular ATP.

The aim of this study was to find out the possibility of using Na+-K+-ATPase activity as a biomarker for the diagnosis of individuals with different physiological conditions.

The activity of Na+-K+ ATPase was determined in blood samples collected from different pathological and physiological conditions such as pregnancy, smoking, diabetes and renal dysfunction compared with healthy subjects matched for age and sex.

The Na+-K+ ATPase activity in pregnancy (0.094 ± 0.0051 µM Pi/min. mg protein), smoking (0.064 ± 0.0011 µM), diabetes (0.047 µM 0.002 µM) and kidney disease (0.069 ± 0.0014 µM) was higher compared to the measurements in healthy individuals (0.0081 ± 0.0031 µM).

Na+-K+ATPase specific activity is a biomarker for the diagnosis of individuals with different physiological diseases.

Partial Text

Studies have shown that Na+-K+-ATPase activity was altered in disrupted red blood cell membranes1 and this enzyme can be the site of active transport of Na+ and K+ in intact red cells2. The enzyme is often referred to as Na+-K+ pump because it pumps Na+ out and K+ into the cell against gradients with the concomitant hydrolysis of intracellular ATP3. There are three types of ATPase: P-type ATPases, V-type ATPases and ABC transporters for ATP binding cassette. The distinguishing functional characteristic of P-type ATPases is that the hydrolysis of ATP that occurs during the catalytic cycle results in the phosphorylation of the transport protein itself. This phosphorylation results in a change in the conformation of the protein that, in turn, plays a part in the translocation of one or more substrate molecules across the membrane4.

Sucrose, magnesium chloride hexahydrate, ascorbic acid, sodium chloride, potassium chloride, ammonium molybdate, ethylenediaminetatra-acetic acid (EDTA), sodium hydroxide, sodium dodecyl sulphate (SDS), sulfuric acid , hydrochloric acid and Tris tris [hydroxymethyl] aminoethane were purchased from BDH limited Poole, England. Adenosine-5′- triphosphate disodum salt and ouabain were obtained from Sigma Chemical Company St. Louis, MO, USA.

The data were logged into personal computer and analyses of data were performed using SPSS statistical package version 22. T-test was used for comparing means. P value was considered to be statistically significant if it was < 0.005. In pregnancy, as shown in Figure 1, the mean activity of Na+, K+ -ATPase of healthy females (n= 21) was compared with pregnant women of the same age group. The mean of enzyme activity for pregnant women 0.0094 ± 0.001 nmol Pi/min. mg protein was higher than in healthy women 0.0086 ± 0.001 nmol Pi/min. mg protein and there was a highly significant difference between these two groups (P= 0.007). The Na+/K+-ATPase is a membrane enzyme which is involved in the regulation of membrane potential, cell permeability of Na+, K+ and Ca2+ and excitatory neurotransmitters. It is also important in cell cycle and differentiation. The balance of Na+ and K+ between the intracellular and extracellular is the main requirement for cellular homeostasis and for different functions3. The rationale of this study was the possibility of utilization of Na+/K+-ATPase as a biomarker for blood diseases.   Source: http://doi.org/10.4314/ahs.v17i4.31

 

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