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Local exposure to light with hollow cathode lamp radiating band spectrum typical of manganese, copper, potassium, sodium, calcium, and magnesium enhances migration of these elements from the solution applied to the skin to the blood in rats. This effect is most pronounced at low initial blood level of manganese. Its serum concentration increased 17-fold after application of manganese salts and exposure to hollow cathode lamp radiating manganese spectrum.

This study was designed to test the authors' hypothesis that dopamine passes from dopamine-synthesizing cells in the brain to the systemic circulation prior to the formation of the blood-brain barrier during ontogenesis. High-performance liquid chromatography studies demonstrated that peripheral blood dopamine levels before formation of the blood-brain barrier-in rat fetuses and neonates-are significantly higher than after formation of the barrier in adult rats, providing indirect evidence in support of the hypothesis. Furthermore, formation of the blood-brain barrier is accompanied by a significant increase in dopamine levels in the rat brain. Direct evidence for the hypothesis was obtained in the form of a sharp decrease in blood dopamine levels in fetuses after lesioning of dopamine-synthesizing neurons in the brain by encephalectomy.