Study explains why shift workers are vulnerable to heart problems

Recent research by the Medical Research Council (MRC) demonstrates how circadian rhythms in heart cells help to change heart function. It might help elaborate the predominance of heart problems in shift workers.

Study explains why shift workers are vulnerable to heart problems
Image Credit: UK Research and Innovation.

The study is the first of its kind to depict that heart cells regulate their circadian rhythms by daily changes in the ion levels inside the cell.

It was earlier considered that ion concentrations inside the cell were constant. But researchers recently identified that these concentrations of ions alter based on the daily demands of lives, enabling the heart to better accommodate and sustain a higher heart rate when active.

Important new insights

The presence of daily clocks in heart cells and other tissues generally synchronized by hormonal signals adjust to the internal daily rhythms with the day and night cycle is well known.

The presence of daily rhythms of heart function is known for years. It was attributed to the increased stimulation by the nervous system during the daytime.

The recent research by the Medical Research Council (MRC) Laboratory for Molecular Biology in Cambridge illustrates that these circadian rhythms within each heart cell are also capable of affecting heart rate. The research was supported by

  • MRC
  • AstraZeneca Blue Sky Initiative

Explaining heart problems

The researchers remark that comprehending how the changes in ion levels modify heart function over the day might help elucidate the susceptibility of heart problems in shift workers.

This occurs as the ion rhythms induced by the clocks in the heart can become “out of sync” due to the stimulation from clocks in the brain. The observation from the study can result in enhanced treatments and preventative measures for fighting heart conditions.

Developing our understanding

The research was carried out using mice and cells in the laboratory. The observations were supported by recent associated research by collaborators, headed by Professor David Bechtold at the University of Manchester.

The research illustrated that circadian rhythms in heart rate and electrical activity are obvious in mice and humans. A quick change in sleep patterns or behavioral routine may upset the normal heart rhythms.

Both pieces of research together indicate that lifestyles that challenge the natural internal clock might result in the decoupling of internal circadian rhythms within heart cells. In other words, the heart clocks no longer foresee the fluctuations needed, for most people, would be greater in the daytime.

Pushing effective treatments

The ways in which heart function changes around the clock turned out to be more complex than previously thought. The ion gradients that contribute to heart rate vary over the daily cycle. This likely helps the heart cope with increased demands during the day when changes in activity and cardiac output are much greater than at night when we normally sleep.”

Dr John O’Neill, Laboratory of Molecular Biology, Medical Research Council, UK Research and Innovation

It opens up the exciting possibility of more effective treatments for cardiovascular conditions, for example by delivering drugs at the right time of day,” added Dr O’Neill.

This really interesting research supported through the MRC AstraZeneca Blue Sky Initiative shows the incredible potential for innovative academic-industry relationships to push the frontiers of discovery science. It addresses fundamental, unanswered questions about how the body works and points to exciting new possibilities for therapeutic innovations.”

Dr Megan Dowie, Head, Molecular and Cellular Medicine, Medical Research Council, UK Research and Innovation

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