Comparison of blood pressure and thermal responses in rats exposed to millimeter wave energy or environmental heat

Nancy J. Millenbaugh, Johnathan L. Kiel, Kathy L. Ryan, Robert V. Blystone, John E. Kalns, Becky J. Brott, Cesario Z. Cerna, William S. Lawrence, Laura L. Soza, Patrick A. Mason

    Research output: Contribution to journalArticlepeer-review

    14 Scopus citations

    Abstract

    Electromagnetic fields at millimeter wave lengths are being developed for commercial and military use at power levels that can cause temperature increases in the skin. Previous work suggests that sustained exposure to millimeter waves causes greater heating of skin, leading to faster induction of circulatory failure than exposure to environmental heat (EH). We tested this hypothesis in three separate experiments by comparing temperature changes in skin, subcutis, and colon, and the time to reach circulatory collapse (mean arterial blood pressure, 20 mmHg) in male Sprague-Dawley rats exposed to the following conditions that produced similar rates of body core heating within each experiment: (1) EH at 42°C, 35 GHz at 75 mW/cm, or 94 GHz at 75 mW/cm under ketamine and xylazine anesthesia; (2) EH at 43°C, 35 GHz at 90 mW/cm, or 94 GHz at 90 mW/cm under ketamine and xylazine anesthesia; and (3) EH at 42°C, 35 GHz at 90 mW/cm, or 94 GHz at 75 mW/cm under isoflurane anesthesia. In all three experiments, the rate and amount of temperature increase at the subcutis and skin surface differed significantly in the rank order of 94 GHz more than 35 GHz more than EH. The time to reach circulatory collapse was significantly less only for rats exposed to 94 GHz at 90 mW/cm, the group with the greatest rate of skin and subcutis heating of all groups in this study, compared with both the 35 GHz at 90 mW/cm and the EH at 43°C groups. These data indicate that body core heating is the major determinant of induction of hemodynamic collapse, and the influence of heating of the skin and subcutis becomes significant only when a certain threshold rate of heating of these tissues is exceeded.

    Original languageEnglish (US)
    Pages (from-to)625-632
    Number of pages8
    JournalShock
    Volume25
    Issue number6
    DOIs
    StatePublished - Jun 1 2006

    Keywords

    • Hyperthermia
    • Microwaves
    • Nonionizing
    • Radio frequency radiation
    • Skin
    • Stroke

    ASJC Scopus subject areas

    • Emergency Medicine
    • Critical Care and Intensive Care Medicine

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