Changes in Plasma Tryptophan and Melatonin Content in Penned Sheep

Abstract

The present study was undertaken to examine the relationship between the plasma levels of melatonin and its precursor tryptophan. No circadian changes in plasma total tryptophan content were evident which could be related to the marked night-time rise in plasma melatonin. An automated programmable blood sampling device suited to studies of circadian rhythms in blood constituents is described.