Abstract
Investigations on the effect of X-rays on cells cultivated in vitro have been limited with few exceptions to an analysis of irradiation effects on the outgrowth and mitotic activity of cell colonies. 1 Our knowledge of the radiosensitivity of other aspects of cell activity is slight. We considered it justified, therefore, to undertake comparative studies in cell cultures on the sensitivity to irradiation of a variety of cell functions. The following is an account of experiments on the effect of X-rays on muscular contraction and ciliary movement.
Few attempts have been made to influence the kinetic activity of cells and tissues in vitro by means of X-rays. (Prime, 2 Gassul, 3 Haberlandt and Sanders, 4 Heeren, 5 Heine, 6 Scott. 7 ) In all these experiments no definite inhibiting effect was obtained owing to the small doses employed.
In our experiments we used an X-ray tube which was operated at a tension of ca 35 KV and a current of 30mA with a copper anti-cathode. The window was aluminium foil 30μ in thickness. Absorption analysis showed that the rays which penetrated through the window and the 0.03 mm thick mica coverglass of the culture were mainly copper-K-rays. The X-ray intensity was about 95,000 r/min at the distance of the irradiated subject.
The following experiments were carried out:
1. Effect of X-rays on the contraction of heart muscle. Fragments of myocardium of 7-day-old embryos in hanging drop cultures were used. Irradiation was carried out 2-4 hours after ex-plantation and its effect was observed about 10 minutes after completion of irradiation. A total of 92 heart muscle cultures were irradiated.
To obtain complete and immediate cessation of heart muscle contraction in culture it is necessary to use doses of 500-700,000 r.
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