Effects of morphine and pentobarbitone on acetylcholine synthesis by rat cerebral cortex.

1. The synthesis of carbon-14-labelled acetylcholine ((14)C-ACh) from carbon-14 uniformly labelled glucose (U-(14)C-D-glucose) under different conditions was studied.2. The ability of cerebral cortex slices and minces from morphine-treated and pentobarbitone-treated rats incubated in 4 mM K(+) medium to form (14)C-ACh was markedly reduced as compared with those from control animals.3. The ability of slices from drug-treated and control animals incubated in 31 mM K(+) medium to form (14)C-ACh was similar.4. Cerebral cortex homogenates from both groups of animals in either 4 or 31 mM K(+) medium formed similar amounts of (14)C-ACh.5. These findings add further support to the hypothesis that the concentration of ACh at the site of synthesis governs the rate of formation of the neurotransmitter.