MOVEMENT OF SUBSTANCE PROXIMO-DISTALLY IN NERVE AXONS AS STUDIED WITH SPINAL CORD INJECTIONS OF RADIOACTIVE PHOSPHORUS
Small volumes of radioactive phosphorus (P/sup 32/) were injected into the lumbar 7th spinal cord of cats by means of fine glass capillaries to study the movement of substance down the motor axons. A gradient of flow over a period of days was indicated when the ventral roots were divided into portions proximal and distal from the cord and each measured for its content of P/sup 32/ activity. The ratio of P/sup32/ activity of the lower to upper portions increased exponcntially when plotted as a function of the number of days after injection. The possibilities of intra-axonal distal flow following an uptake of P/sup 32/ by the cell body and dendrite,and an adventitious interaxonal lendoneural) distal flow was examined. Activity in the ventral roots was always greater than that in the dorsal roots. The asymmetry supports thc concept of an intraaxonic movement since interaxonic flow should bc equally possible in the ventral and dorsal roots. A group of animals had the L7 segments of their cords asphyxiated by means of local pressure which destroyed the motoneurons. In these animals, P/sup 32/ was injected 1 week later. There was a greatly diminished P/sup 32/ content in the ventral roots of animals so treated when sampled 1 week after injection. This evidence also supports the concept of an intra-axonic movement of substance distally in the axons. (auth)
- Research Organization:
- Univ. of Texas, Galveston
- NSA Number:
- NSA-12-015314
- OSTI ID:
- 4324948
- Journal Information:
- American Journal of Physiology (U.S.), Journal Name: American Journal of Physiology (U.S.) Vol. Vol: 194; ISSN AJPHA
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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