AXOTOMY-INDUCED CHANGES IN CA2-GANGLION CELLS( HOMEOSTASIS IN RAT SYMPATHETIC)

Some of the marked biochemical and electrophysiological changes provok ed by section of the axon in mature neurons suggest that the intracell ular calcium concentration ([Ca2+](i)) may be increased. We have measu red the [Ca2+](i) using the fluorescent indicator Indo-1 microinjected into rat superior cervical ganglion neurons. No differences in restin g [Ca2+](i) levels were found between control neurons and cells which had been axotomized 7-10 days before. However, the rise in [Ca2+](i) e voked by orthodromic or antidromic stimulation and the recovery after the stimulating train were considerably slower in axotomized neurons t han in control cells. We also found that the number of calbindin-D28k- immunopositive cells in the ganglion increases after axotomy, which co uld be related to the observed differences in calcium homeostasis.