The ultrawide-band (UWB) electromagnetic pulses are used as a new modality in radar technology. Biological effects of extremely high peak E-field, fast rise time, ultrashort pulse width, and ultrawide band have not been investigated heretofore due to the lack of animal exposure facilities. A new biological effects database is needed to establish personnel protection guidelines for these new type of radiofrequency radiation. Functional indices of the cardiovascular system (heart rate, systolic, mean, and diastolic pressures) were selected to represent biological end points that may be susceptible to the UWB radiation. A noninvasive tail-cuff photoelectric sensor sphygmomanometer was used. Male Wistar-Kyoto rats were subjected to sham exposure, 0.5-kHz (93 kV/m, 180 ps rise time, 1.00 ns pulse width, whole-body averaged specific absorption rate, SAR = 70 mW/kg) or a 1-kHz (85 kV/m, 200 ps rise time, 1.03 ns pulse width, SAR = 121 mW/kg) UWB fields in a tapered parallel plate GTEM cell for 6 min. Cardiovascular functions were evaluated from 45 min to 4 weeks after exposures. Significant decrease in arterial blood pressures (hypotension) was found. In contrast, heart rate was not altered by these exposures. The UWB radiation-induced hypotension was a robust, consistent, and persistent effect.

Animals↗

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Focal sarcoplasmic reticulum calcium stores and diffuse inositol 1,4,5-trisphosphate and ryanodine receptors in human myometrium.

Intracellular calcium stores of human uterine myocytes in primary and second passage cell culture were visualized using the low-affinity calcium-sensitive fluorescent dye, fluo-3FF. The calcium stores appeared as numerous small (0.2-0.5 microm diameter) focal fluorescences. The stores were not depleted by exposing the cells to oxytocin or ryanodine under standard conditions. The stores were rapidly depleted by oxytocin or ryanodine exposure when sarcoplasmic reticulum (SR) calcium re-uptake was inhibited by pretreatment with thapsigargin. Immunofluorescence experiments indicated that both ryanodine and inositol 1,4,5-trisphosphate (IP(3)) receptors were smoothly distributed throughout the SR, and neither receptor co-localized with the calcium stores. Since IP(3) and ryanodine calcium channels are tightly associated with their receptor, these results suggest that SR calcium release occurs via second messenger channels that are remote from the SR calcium stores. These observations are consistent only with a mechanism for release of calcium stores where the SR serves three functions: (1) as site of calcium storage, (2) as the structure that contains the IP(3)- and ryanodine receptors and their associated release channels, and (3) as a conduit between the calcium stores and the release channels.

Calcium↗