Factors influencing the calculation of results from studies of the release of tritiated neurotransmitters from superfused slices of guinea pig striata.
Slices of guinea pig striata were incubated with tritiated choline, dopamine, or serotonin and the release of radioactive transmitter was studied in a superfusion system. Some experiments were also done on the release of [3H]acetylcholine from rat striatal slices. For analysis of the results, various parameters of the system were determined in order to establish the most reliable method of assessing drug effects on transmitter release. Peaks of radioactivity (S1 and S2) above basal release of radioactivity (B1 and B2) were observed after two depolarizations of the nerve endings with high K+ buffer. Each stimulation was for 2 min, and S2 occurred 20 min after S1. There was a highly significant correlation between S1 and the protein content of the slices for acetylcholine release from guinea pig striata. Basal release of radioactivity, and the ratio S2/S1, were not sensitive to minor changes in the experimental conditions. It was concluded that S2/S1, rather than S1 or S1/B1, should be used as a measure of drug effects on release. The experiments also demonstrated that re-uptake of released neurotransmitter is operative in the superfusion system for dopamine, but not for serotonin. Differences were observed between the rat and the guinea pig with respect to the release of [3H]acetylcholine.
Dawson
R M
RM
Materials Research Laboratory, Defence Science & Technology Organization, Ascot Vale, Victoria, Australia.
D000109:Acetylcholine / Q000032:analysis / Q000378:metabolism; D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000032:analysis / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009419:Nerve Tissue Proteins / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000032:analysis / Q000378:metabolism*; D009627:Nomifensine / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000032:analysis / Q000378:metabolism
D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; D009627:Nomifensine; D012701:Serotonin; D000109:Acetylcholine; D004298:Dopamine