||Temperature-Specific Inhibition of Human Red Cell Na(1+)/K(1+) ATPase by 2450-MHz Microwave Radiation.
Allis, J. W. ;
Sinha-Robinson, B. L. ;
||Health Effects Research Lab., Research Triangle Park, NC. Experimental Biology Div.
Radiation effects ;
In vitro analysis ;
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The ATPase activity in human red blood cell membranes was investigated in vitro as a function of temperature and exposure to 2450 MHz (CW) microwave radiation. Assays were conducted spectrophotometrically during microwave exposure with a custom-made spectrophotometer-waveguide apparatus. Temperature profiles of total ATPase and Ca+2 ATPase (ouabain-inhibited) activity between 17 and 31 C were graphed as an Arrhenius plot. Each data set was fitted to two straight lines which intersected between 23 and 24 C. The difference between the total and Ca+2 ATPase activities, which represented the Na+/K+ ATPase activity, was also plotted and treated similarly to yield an intersection near 25 C. Exposure of membrane suspensions to a 6 W/kg dose rate at 1 C intervals between 23 and 27 C, resulted in an activity change only for the Na+/K+ ATPase at 25 C. The activity decreased by approximately 35% compared to sham-irradiated samples. An hypothesis based on the interaction of microwave radiation with enzyme structure during a conformational rearrangement is proposed as an explanation for the effect.