Quinacrine and release of purines from the rat hypothalamus.

The acridine derivative quinacrine accumulates in certain endocrine cells and nerve endings. It has been suggested that it binds to ATP stored in granules in such cells. For this reason the uptake and release of quinacrine and the ATP-precursor adenine was studied in slices and in crude synaptosomes from the rat hypothalamus. Both quinacrine and purines were taken up and after uptake there was a spontaneous release. The rate of purine release could be stimulated by nerve stimulation, the depolarizing agent veratridine, and by omitting glucose from the medium. Veratridine-induced purine release was inhibited by dipyridamole, an inhibitor of carrier-mediated nucleoside transport, whereas release induced by glucose deprivation was not. None of the procedures caused release of labelled quinacrine. The results are not compatible with the opinion that the bulk of the purines are released from specific storage vesicles that have the capacity specifically to bind quinacrine.