Stimulation of piriform- and neo-cortical tissues in an in vitro flow-system: metabolic properties and release of putative neurotransmitters.

TLDR: Multiple samples from the piriform cortex and neocortex of the guinea pig were maintained in separate incubation vessels through which incubation solutions based on Krebs‐Ringer bicarbonate glucose media were caused to flow for chosen periods at specified rates.

Abstract: — (1) Multiple samples from the piriform cortex and neocortex of the guinea pig were maintained in separate incubation vessels through which incubation solutions based on Krebs-Ringer bicarbonate glucose media were caused to flow for chosen periods at specified rates. (2) The tissues were held in defined positions in relation to electrodes; in some experiments electrical stimuli were applied and in others incubation media were changed with respect to their oxygen, K+ or glutamate content. (3) With media flowing at 3–4 ml/min, the incubated tissues were similar in contents of K salts and phosphocreatine, and in rate of glycolysis to those incubated in non-flowing media. The tissues responded to electrical stimulation by increase in glycolysis and decrease in phosphocreatine and K content. (4) During pre-incubation periods in non-flowing media, samples of piriform cortex were exposed to solutions containing 3H-labelled glycine, noradrenaline or 5-hydroxytry-ptamine and on anlaysis were found to contain the labelled compounds at concentrations four to seven times those of the surrounding media. The labelled compounds were gradually released into the flowing incubation media, and the release of noradrenaline and 5-hydroxytryptamine was accelerated by electrical stimulation. (5) Release of the two bases was also modified by added reagents and the course of their release is discussed in relation to other metabolic changes concomitantly observed.