Circadian Rhythm in Uptake of Tritiated Thymidine by Kidney, Parotid, and Duodenum of Isoproterenol-Treated Mice

The total uptake of [(3)H]thymidine by the mouse parotid gland, kidney, and duodenum exhibits a circadian rhythm. A single injection of isoproterenol changes the phasing and amplitude of these rhythms. Depending on the organ, there are certain points in the circadian time structure when isoproterenol stimulates or inhibits the uptake of thymidine; at other time points there is no difference between the responses to isoproterenol and to saline.