Acute treatment of constant darkness increases the efficiency of ATP synthase in rat liver mitochondria.
The circadian oscillations of many physiological processes provide an endogenous temporal program for the adaptive synchronization of mammals to the fluctuating external world. The lack of exposure to light causes the circadian system to undergo a process of dark adaptation similar to dark adaptation in the visual system. The aim of the present work was investigate the effect of acute treatment of constant darkness on mitochondrial ATP synthase activities and membrane fluidity in liver from male rat. We found that ATP synthase activity was not changed by the treatment. However ATPase activity and membrane fluidity were significantly diminished and pH gradient driven by ATP hydrolysis was incremented, in comparison from samples from rats kept on normal light/dark cycles. Additionally, the treatment of constant darkness diminishes the passive proton permeability of the inner mitochondrial membrane. In conclusion constant darkness induces a more efficient coupling between proton transport and catalysis, and increment the efficiency of the enzyme because the ratio of ATP synthase/ATPase activity was higher. These results exhibited the physiological adaptation of liver mitochondria to acute treatment of constant darkness in order to satisfy the cellular energy demand.
Ramírez-Iñiguez
Ana Laura
AL
Departamento de Ingeniería Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara, Jalisco, México.
Ortiz
Genaro Gabriel
GG
El Hafidi
Mohammed
M
Rincón-Sánchez
Ana Rosa
AR
Macías-Rodríguez
Ernesto
E
Pacheco-Moisés
Fermín Paul
FP
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D003624:Darkness; D006863:Hydrogen-Ion Concentration; D008297:Male; D008560:Membrane Fluidity / Q000502:physiology; D008930:Mitochondria, Liver / Q000201:enzymology*; D051336:Mitochondrial Membranes / Q000502:physiology; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism*; D023421:Models, Animal; D051381:Rats; D017208:Rats, Wistar
D025261:Mitochondrial Proton-Translocating ATPases