Temporal profile of levels of monoamines and their metabolites in striata of rats implanted with dialysis tubes.

We have measured the levels of monoamines and their metabolites in rat striata implanted with a dialysis tube, in contralateral nonimplanted striata, and in dialysates obtained from the dialysis tube. The perfusion was done with Ringer solution. The animals were perfused either for a continuous period of 7 h at 1 day after implantation or for periods of 2 h on days 1, 4, and 7 after implantation. In animals perfused for 7 h, levels of monoamine metabolites in dialysates remained stable for the first 4 h of perfusion, but a reduction was observed during the last 3 h. In animals perfused for 2 h on days 1, 4, and 7 after implantation, we observed a progressive reduction in levels of metabolites in dialysates with respect to the first day of perfusion. The levels of dopamine and its metabolites in the striata in which a dialysis cannula had been implanted showed a progressive reduction during the period postimplantation comparable to that observed in dialysates. The levels of 3-methoxytyramine, 3,4-dihydroxyphenylacetic acid, and homovanillic acid were elevated 24 h after implantation in the implanted striata with respect to the contralateral nonimplanted striata, but 7 days after implantation, the levels of dopamine were decreased in the implanted striata, and the levels of metabolites were unchanged.