Effects of field orientation during 700-MHz radiofrequency irradiation of rats

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Physiological Chemistry and Physics and Medical NMR; (USA)

OSTI ID:6991410

Frei, M R; Jauchem, J R; Padilla, J M ^[1]

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1. School of Aerospace Medicine, Brooks AFB, TX (USA)

Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 700-MHz continuous-wave radiofrequency radiation (RFR) in both E and H orientations. Irradiation was conducted at whole-body average specific absorption rates (SARs) of 9.2 and 13.0 W/kg (E and H, respectively) that resulted in approximately equivalent colonic specific heating rates (SHRs). Exposures were performed to repeatedly increase colonic temperature by 1 degree C (38.5 to 39.5 degrees C). Tympanic, tail, left and right subcutaneous (toward and away from RFR source), and colonic temperatures, arterial blood pressure, and respiratory rate were continuously recorded. In spite of equivalent colonic SHRs and the reduced E-orientation average SAR, the right subcutaneous, tympanic, and tail SARs, SHRs and absolute temperature increases were significantly greater in E than in H orientation. The cooling rate at all monitoring sites was also significantly greater in E than in H orientation. Heart rate and mean arterial blood pressure significantly increased during irradiation; however, changes between orientations were not different. Respiratory rate significantly increased during irradiation in H, but not in E orientation. These results indicate that during resonant frequency irradiation, differences occur in the pattern of heat deposition between E- and H-orientation exposure. When compared with previous investigations performed at supraresonant frequencies, the lower level of cardiovascular change in this study was probably related to the lower periphery-to-core thermal gradient.

• OSTI ID: 6991410
• Journal Information: Physiological Chemistry and Physics and Medical NMR; (USA), Vol. 21:1; ISSN 0748-6642
• Country of Publication: United States
• Language: English

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