Kidneys have an innate clock that affects many metabolic processes in the body

Many of the body's processes follow a natural daily rhythm or circadian clock that is based on regular light-dark cycles as Earth rotates. Dmitri Firsov, PhD, Natsuko Tokonami, PhD (University of Lausanne, in Switzerland) and their colleagues have now demonstrated that the kidney possesses such an intrinsic circadian clock that regulates and coordinates a variety of the organ's functions. "Since urine formation and excretion by the kidney is one of the most easily detectable rhythmic processes (we are forming and excreting much more urine during the day), we hypothesized that at least a part of this rhythmicity is dependent on the circadian clock mechanism," said Dr. Tokonami.

By blocking kidney cells' expression of a gene that is critically involved in the circadian clock system, the team found that the clock is responsible for the temporal adaptation of kidney function to the light and dark phases of the day that correspond to activity and rest. Such adaptations have an important effect on the levels of various amino acids, lipids, and other components of blood in the body. Furthermore, in individuals who take medications, the kidney's circadian clock controls the process of drug elimination from the body and therefore can influence the duration of a drug's action and the effectiveness of the therapy.

"We've shown that the circadian clock in the kidney plays an important role in different metabolic and homeostatic processes at both the intra-renal and systemic levels and is involved in drug disposition," said Dr. Firsov.