Effects of weak amplitude-modulated microwave fields on calcium efflux from awake cat cerebral cortex
✍ Scribed by W. R. Adey; S. M. Bawin; A. F. Lawrence
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- English
- Weight
- 817 KB
- Volume
- 3
- Category
- Article
- ISSN
- 0197-8462
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✦ Synopsis
Abstract
Calcium (^45^Ca^2+^) efflux was studied from preloaded cortex in cats immobilized under local anesthesia, and exposed to a 3.0‐mW/cm^2^ 450‐MHz field, sinusoidally amplitude modulated at 16 Hz (modulation depth 85%). Tissue dosimetry showed a field of 33 V/m in the interhemispheric fissure (rate of energy deposition 0.29 W/kg). Field exposure lasted 60 min. By comparison with controls, efflux curves from field exposed brains were disrupted by waves of increased ^45^Ca^2+^ efflux. These waves were irregular in amplitude and duration, but many exhibited periods of 20–30 min. They continued into the postexposure period. Binomial probability analysis indicates that the field‐exposed efflux curves constitute a different population from controls at a confidence level of 0.96. In about 70% of cases, initiation of field exposure was followed by increased end‐tidal CO^2^ excretion for about 5 min. However, hypercapnea induced by hypoventilation did not elicit increased ^45^Ca^2+^ efflux. Thus this increase with exposure does not appear to arise as a secondary effect of raised cerebral CO~2~ levels. Radioactivity measurements in cortical samples after superfusion showed ^45^Ca^2+^ penetration at about 1.7 mm/hr, consistent with diffusion of the ion in free solution.