Diurnal variation of plasma concentrations of cortisol, aldosterone and electrolytes in the ram.

The peripheral plasma concentrations of cortisol, aldosterone and electrolytes were measured simultaneously in 2 groups of 20 + 8 rams sampled respectively every 3 hours in June 1974 and hourly in June 1975 over a 24-hr period, in the Algiers area. In spite of large individual variations, the mean plasma concentrations of cortisol and aldosterone exhibited synchronous diurnal changes: they were highest in the morning, decreased during the afternoon until 18.00 h, and remained lowest during the first part of the night.