Circadian rhythms of renal phosphohydrolases analysed by Cosinor method

Rhythmometric analysis of hydrolytic enzymes of mouse kidney has been performed on circadian time scale using the F test. Significant rhythms were detected in glucose-6-phosphatase (G6Pase), inorganic pyrophosphatase (InPPase) and alkaline phosphatase (AlPase) on protein and fresh weight basis. Acrophase (time for peak activity) of G6Pase, InPPase and AlPase per mg protein was at 9.9 degrees (1.0 hr), 88.5 degrees (6.0 hr) and at 342.3 degrees (20 hr) respectively. ATPase, which did not show significant rhythm (mean +/- SD = 4.51 +/- 0.30), had a peak value at 32.1 degrees (2.14 hr) with an amplitude of 0.31 units on protein basis. However, G6Pase and AlPase oscillated with high amplitudes (0.18 and 0.71) across the mean value (mesor) of 0.68 +/- 0.3 and 1.43 +/- 0.46 units respectively and with a phase shift of 5 hr. Since G6Pase is a multicomponent and multifunctional enzyme having several overlapping enzyme activities (viz. InPPase), coordinated events of G6Pase, InPPase and ATPase in the regulation of daily renal functions have been mapped in the intact animals, along a physiologic time scale.