The puzzle of excess calcium

Too much calcium in the heart can cause sudden cardiac arrest in heart failure patients but scientists have been puzzled by how and why this happened – until now

Research from the University of Bristol has revealed that protein kinase C (PKC) can cause excessive openings in RyR2 channels which can allow too much calcium to be released into the cardiac muscle.

Calcium is known to regulate cardiac muscle contraction, and with each heartbeat, calcium is released from intracellular stores – the sarcosplasmic reticulum (SR) – through specialised channels called ryanodin receptors, or RyR2. PKC disrupts this flow of calcium and causes a disturbance in the normal rhythm of the heart, or arrhythmias.

“Our experiments measure the opening and closing of single calcium channels,” said Dr Rebecca Sitsapesan, a reader in pharmacology at the university. “We have been able to show that PKC changes the way in which in which the calcium channels open and this may be one of the reasons why too much calcium is released in heart cells at the wrong time and why patients with heart failure are at risk of sudden cardiac death.”

Sitapesan hopes the research – which was funded by the British Heart Foundation – will open up new possibilities for combating heart disease.

“Our findings reveal a novel mechanism for opening calcium channels inside heart cells,” she said. “This new information will help us to design new treatments to prevent this occurring, and help in the fight against heart disease.”