THE FROG'S EYE ELECTRORETINOGRAM AS AN IMMEDIATE X-RAY EFFECT
The electroretinogram (ERG) was recorded in the isolated, dark-adapted eye of Rana temporaria, and compared with the light-induced ERG, by the use of 45 kv x rays, the dose rate being varied by aluminum filters of appropriate thickness. With x-ray dose rates ranging from 2 to 67 r/ sec it was possible to register an ERG which qualitatively had a similar shape as a normal light ERG. In most cases it clearly showed an on-effect (b-wave) and an off-effect (d-wave). With decreasing doses the height of the waves proportionally decreased. Sometimes only an on-response was noted using a dose rate of 50 r/sec, and successive reduction of the b-waves with time was observed. The fatigue phenomenon was always present if the interval between two stimulations was less than 1 min. With intervals >1 the amplitudes remained constant; this period appears to correspond to the time for complete recovery. Diminution of the amplitude with time continued until a min value was reached, the same stimulation now causing a further decrease. Complete disappearance of the waves was never seen, not even using the frequent stimulation cycle of 1 sec on and 1 sec off. In this case the amplitudes were all of the same height with the exception of the first one being much higher. Apparently, after the first stimulus an equilibrium sets in between the fatiguing effect and its recovery. If, after the amplitudes become constant, visible light of intensity was added during the period of observation, a new decrease of the height occurred. The reverse could be demonstrated too; i.e., an ERG induced by light could be reversibly attenuated by x irradiation. A more striking effect of x irradiation on the light ERG was demonstrated when a small light intensity was used; with increasing light intensities the x-ray inhibition of the light ERG decreased. The d-wave of the x- ray ERG, if present, generally varied similarly to the b-wave. However, its decrease was not as obvious because of the much lower amplitude of the d-wave. The influence of x rays on the off-effect in the light ERG was different. In 16 out of 30 experiments a slight increase was noted, in 10 a decrease of the height, and in the remaining 10 no effect. It is concluded that an x-ray ERG can be recorded with small doses of x rays. (BBB)
- Research Organization:
- State Univ., Groningen, Netherlands
- NSA Number:
- NSA-18-000084
- OSTI ID:
- 4171790
- Journal Information:
- Koninkl. Ned. Akad. Wetenschap, Proc., Vol. Vol: Ser. C, 64; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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