Study type: Medical/biological study (experimental study)

Microwave radiation effects on the thermally driven oxidase of erythrocytes. med./bio.

Published in: Int J Hyperthermia 1986; 2 (2): 201-212

Aim of study (acc. to editor)

To study the effects of 2450 MHz microwave irradiation on oxidation/autoxidation processes in erythrocytes in sheep red blood cells (SRBCs)

Background/further details

The sheep red blood cells (SRBCs) were labelled with a concanavalin A-luminol-bovine serum albumin conjugate specific for the transmembrane anion transport protein (Band 3; i.e. the conjugate binds to Band 3). The band 3 transmembrane protein is the predominant membrane transport protein in red blood cells and plays a central role in structure and function of those cells.
The authors consider a mechanism involving the anion (superoxide) channel (composed of dimeric units of the transmembrane protein Band 3) and membrane-associated haemoglobin and enzymes.
Following exposure to microwave or air heating, the decrease in residual chemiluminescence was measured as an indication of oxidase activity (important in the oxygen release process from haemoglobin). The source of the chemiluminescence is the oxidation of luminol (of the conjugate) by superoxide, hydrogen peroxide and, perhaps, hydroxyl-free radical formed during the thermally induced autoxidation of oxyhaemoglobin; superoxide escapes the erythrocytes through the anion channel (composed of dimeric units of the transmembrane protein Band 3; see above).
The temperature was held constant at 25, 37, 40, 42 or 45°C.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: CW
Exposure duration: 10 min
  • SAR: 91 mW/g mean (cf. remarks) (+/- 4 W/kg)

Exposure 1

Main characteristics
Frequency 2.45 GHz
Exposure duration 10 min
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup Aliquots of SRBCs in PBS were heated in cellulose nitrate tubes (1.2 cm x 5.1 cm) in the microwave exposure device.
Parameters
Measurand Value Type Method Mass Remarks
SAR 91 mW/g mean calculated cf. remarks +/- 4 W/kg

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

Air heating resulted in a significant decrease in residual chemiluminescence at temperatures above 37°C. Microwave radiation inhibited the decline in residual chemiluminescence above 37°C (at 45°C the inhibition was 40%).
The results suggest microwave irradiation either reversibly altered the thermodynamics of oxygen binding to haemoglobin or failed to energize a significant portion of the haemoglobin molecules to the thermal threshold of haemoglobin autoxidation.
The release of superoxide and peroxides from red blood cells in small blood vessels subjected to hyperthermia could result in oedema and an influx of granulocytes into surrounding tissues. Microwave radiation, with exposure parameters based on these results, is expected to minimize these effects.

Study character:

Study funded by