The kidneys contain a circadian clock that is responsible for many metabolic processes, say researchers.
Study coauthor Dr. Dmitri Firsov, PhD, of the University of Lausanne, Switzerland, and colleagues recently published their findings in the Journal of the American Society of Nephrology.
The circadian clock is the body's natural time-keeping mechanism, located in the suprachiasmatic nucleus of the brain. It controls our circadian rhythms - changes to physical, mental and behavioral processes that closely follow a 24-hour cycle.
In humans and most other living things, circadian rhythms primarily respond to sunlight and darkness. For example, at nighttime, the circadian clock tells the body it is time to sleep by triggering an increase in melatonin production.
Now, Dr. Firsov and colleagues describe how a circadian clock in the kidneys plays a key role in many of their functions.
A key role of the kidneys is to clear waste products and excess fluids from the blood. The kidneys contain millions of nephrons, which are functional units that filter the blood. Any unwanted products are excreted from the body in the form of urine.
According to the National Kidney Foundation, around 2 quarts of fluid are removed from the body through urination every 24 hours.
Kidney clock regulates adaptation to light-dark cycles
Study coauthor Dr. Natsuko Tokonami, also of the University of Switzerland, notes that the kidney forms and excretes significantly more urine during the day, making it "one of the most easily detectable rhythmic processes."
"We hypothesized that at least a part of this rhythmicity is dependent on the circadian clock mechanism," she added.
For their study, the researchers inhibited the expression of a gene in the kidneys called Bmal1, which plays a crucial role in the organs' circadian clock mechanism.
By doing so, they found that the innate circadian clock regulates the kidney's ability to adapt to light and dark stages of the day that correlate with activity and rest. The researchers explain that these adaptations play an important role in blood levels of amino acids, lipids and other products.
What is more, the team found that the circadian clock in the kidneys is responsible for eradicating drugs from the body. As such, this internal clock can affect how long a medication stays in the body and how effective it is.
Commenting on the results, Dr. Firsov says:
"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."
Medical News Today recently reported on a study that found eating saturated fats at certain times may interfere with internal body clocks.