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Effects of weak amplitude‐modulated microwave fields on calcium efflux from awake cat cerebral cortex
Author(s) -
Adey W. R.,
Bawin S. M.,
Lawrence A. F.
Publication year - 1982
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.2250030302
Subject(s) - efflux , calcium , chemistry , amplitude , cerebral cortex , anesthesia , endocrinology , medicine , nuclear magnetic resonance , biophysics , biology , biochemistry , physics , quantum mechanics
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.