Phase shifting of liver-glycogen rhythm in intact mice

¹ Medical School, University of Minnesota, Minneapolis; and Cambridge State School and Hospital, Cambridge, Minnesota

After the abrupt inversion of a regimen providing for alternating 12 hours of light and darkness the liver-glycogen rhythm of mice feeding ad libitum shifted gradually, rather than suddenly. This progressive shift of liver-glycogen rhythm was slow during the first 4 days after reversal of lighting regimen and faster thereafter. It was completed within 9 days, in intact mature male C mice. Shift-time and shift-rate change are physiologic characteristics of theoretical and applied interest. Phase shifting of rhythms by environmental means proceeds within temporal bounds set by internal phase controls. The interdependence of superficially related periodic functions can be analyzed by phase shifting through study of their shift times.