Abstract
Plasma corticosterone, Ca++, Mg++, Zn++ and Cu++ concentrations were determined at four hour intervals in male rats subjected to two
different lighting schedules (12L:12D and 12D:12L). Although diurnal rhythms were
observed in these cations when rats were on 12L:12D schedule, only at specific times
did plasma Zn++and Cu++ appear to be related to plasma corticosterone levels; however, when the lighting
schedule was reversed (12D:12L), a new diurnal rhythm in corticosterone, but not in
plasma cations, was established. These data suggest that at physiologic concentrations
corticosterone does not significantly influence the plasma levels of cations, nor
do these cations affect plasma corticosterone levels.
Key words
Diurnal Corticosterone and Cations - Calcium - Magnesium - Zinc - Copper
1 Supported in part by internal grants of the University of Illinois and by the Office
of Naval Research Contract NR 201-020. The authors are indebted to K.Pazderska for
her excellent technical assistance.
