The ability of the heart to function as a pump that drives blood around the body depends on the electrical behaviour of muscle cells from various regions of the heart. Different cardiac regions have distinct electrical events, specialised for their particular roles in the heart.

While studying the electrical activity of heart muscle cells, doctors Jules Hancox and Yin Hua Zhang from Bristol University's School of Medical Sciences found that insulin activates a distinct electrical signal in cellular proteins called 'ion channels'. This particular electrical signal was found to be different from those of known ion channels in the heart and led them to conclude that it was likely to be from a new heart ion channel.

Defects in ion channels are known to be responsible for inherited medical conditions such as cystic fibrosis and some disorders of heart rhythm. A number of drugs used to treat heart rhythm disturbances work by affecting ion channel activity, so new targets for drugs, as well as new drugs, are constantly being sought.

Dr Hancox said: 'Insulin has been tremendously valuable in allowing us to observe this electrical event. What is particularly exciting is that if drugs that modify the activity of this ion channel can now be found, it could in time offer a new means of regulating the heart.'

A report describing this new effect of insulin has just been published in the international journal Circulation Research. It is hoped that further laboratory investigations will identify the new ion channel protein and provide greater insight into how its activity is controlled.

The ability of the heart to function as a muscular pump that drives blood around the body depends on both the electrical and contractile behaviour of muscle cells from the various regions of the heart. Different cardiac regions have distinct electrical events (action potentials), specialised for their particular roles in the heart. The particular profile of action potentials from the various regions depends on the combined activity of special proteins in the cell membrane called ion channels. Much current work on the heart aims to understand the role of particular ion channels in generating the electrical behaviour of heart cells.

As well as being part of Bristol's Physiology Department, Dr Jules Hancox's research group is situated within the Cardiovascular Research Laboratories in Bristol University's Medical School.