Metabolic and Vasomotor Responses of Rhesus Monkeys Exposed to 225-MHz Radiofrequency Energy

摘要

A previous study showed a substantial increase in the colonic temperature of rhesus monkeys (Macaca mulatta) exposed to radio frequency (RF) fields at a frequency near wholebody resonance and specific absorption rates (SAR) of 2 to 3 W/kg. The present experiments were conducted to determine the metabolic and vasomotor responses during exposures to similar RF fields. Five adult male rhesus monkeys were exposed to 225 MHz radiation (E orientation) in an anechoic chamber. The monkeys were irradiated at two carefully-controlled ambient temperatures, either cool (20 C) or thermoneutral (26 C). Power densities ranged from 0 (sham) to 10.0 mW/sq cm with an average whole-body SAR of 0.285 (W/kg)/(mW/sq cm). Two experimental protocols were used, each of which began with a 120-min preexposure equilibration period. Then, one protocol involved repetitive 10-min RF exposures at successively higher power densities with a recovery period between exposures. In the second protocol, a 120-min RF exposure permitted the measurement of steady-state thermoregulatory responses. Metabolic and vasomotor adjustments in the rhesus monkey exposed to 225 MHz occurred during brief or sustained exposures at SARs at or above 1.4 W/kg. Metabolic and vasomotor responses were coordinated effectively to produce a stable deep body temperature. The results show that the thermoregulatory response of the rhesus monkey to an RF exposure at a resonant frequency limits storage of heat in the body. However, substantial increases in colonic temperature were not prevented by such responses, even in a cool environment. Keywords: Microwave, Metabolic heat production, Vasodilation.