Incorporation Du Radiophosphate Plasmatique Dans Les Fractions Phosphates Minéral, Organiques Acido-Solubles Et Phospholipidiques Des Nerfs Sciatiques De Lapin, Normal Et En Voie De Degénérescence Wallérienne

Abstract

Inorganic phosphate exchanges between plasma and sciatic nerve have been measured in the rabbit using a 32PO4 tracer technique. Inorganic phosphate is taken up at the rate of 0.13 microng per hour and per 100 mg fresh weight. Incorporation of plasma radiophosphate is markedly increased into the inorganic and organic acid soluble phosphate fractions of the distal part of the sectioned sciatic nerve. This increase is already signficant within one hour after surgical division, spreading at least 3 cm distally within 6 hours. This high level of incorporation persists until the 29th day of degeneration. These results favour the hypothesis that the axonal continuity maintains the metabolic activity of the Schwann cells at an inframaximal level. We confirm the rapid decrease in total phospholipid concentration in the nerve undergoing Wallerian degeneration as well as the marked increase in their specific activity. We show however that this increase in specific activity is due partly to the increased specific activities of the precursors (organic acid soluble phosphates), partly to the disappearance of a metabolically insert pool (myelin phospholipids). The Schwann cells of the nerve undergoing Wallerian degeneration do not have a more active phospholipid metabolism than their normal counterparts.