The source of acetyl coenzyme A for acetylcholine synthesis in the perfused rat phrenic nerve-hemidiaphragm.

Acetylcholine release by the phrenic nerve was measured in the isolated, perfused rat hemidiaphragm. In controls, the rate of release of acetylcholine increases with time; however, when (--)-hydroxycitrate, an inhibitor of ATP-citrate lyase, is added to the perfusate, the release of acetylcholine stabilizes at a level 40% below the final control value. In this preparation, the capacity of the citrate cleavage pathway to transfer acetyl coenzyme A from the nerve cell mitochondria to the cytosol increases with time; this is not the case for other transport processes.