Bawin and her coworkers have reported changes in binding of calcium after exposure of avian brain tissue to nonionizing electromagnetic radiation. Because calcium is intimately involved in the electrical activity of the brain, their results reveal a heretofore unrecognized potential for nonionizing radiofrequency radiation to affect biological function. We have verified and extended their findings. The forebrains of newly hatched chickens, separated at the midline to provide treatment-control pairs, were labeled in vitro with radioactive calcium. Samples of tissue were exposed for 20 minutes in a Crawford irradiation chamber to 147-MHz radiation, which was amplitude modulated sinusoidally at selected frequencies between 3 and 30 Hz. Power densities of incident radiation ranged between 0.5 and 2 mW cm -2.
Compared with nonirradiated samples, a statistically significant increase in efflux ofcalcium ions (P < 0.01) was observed in irradiated samples at a modulation frequency of 16 Hz and at a power density of 0.75 mW cm -2. Our data confirm the existence of the frequency "window" reported by Bawin et al., as well as a narrow power-density "window" within which efflux of calcium ions is enhanced. 0048-6604/79/1112-S014501.00 93 94 BLACKMAN ET AL.
The dopamine agonist bromocriptine has been widely used to facilitate pregnancy in hyperprolactinaemic women, with a success rate of 80% in relevant cases. Neither the inappropriate hyperprolactinaemia consequent upon bromocriptine withdrawal after conception nor the relative hypoprolactinaemia caused by treatment throughout gestation appears to affect adversely the course and outcome of pregnancy or the endocrine status of the fetus. No teratogenic effect of bromocriptine has been evidenced in humans, and no disturbances in the physical, psychomotor, and intellectual development of the offspring have been observed. Pituitary-tumor enlargement during closely supervised pregnancies very rarely leads to severe and irreversible complications; both the re-institution of bromocriptine treatment in the event of tumor enlargement and its preventive use throughout pregnancy have been shown to be effective measures. It is interesting, moreover, that a reduction of hyperprolactinaemia, compared with pregestational levels, may be seen after bromocriptine-facilitated pregnancies.
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