Medications called calcium channel blockers are sometimes used to treat high blood pressure. Calcium channels allow calcium into the cells and so are linked to muscle contraction; by restricting them, the blocker medications work to reduce the heart beat. However, the channels also have another important function; they are fundamental to the electrical currents which keep the heart beating.
The heart beats through an electrical signal that starts at the top of the heart in the sinoatrial (SA) node. As the electrical signal travels down through the heart, it causes consecutive contractions of the muscle of the different chambers. This electrical signal is generated due to creation of current and a change in voltage when there is an influx of calcium into the cells in the SA node.
It is the calcium channels that are responsible for bringing this calcium into these cells; so the channels are fundamental for a steady heart beat. A reduction in the working capacity of the calcium channels would cause a fall in blood pressure and lead to fainting and, if left untreated, potentially death. Patients who have the above symptoms generally need to be fitted with a cardiac pacemaker.
The new research by Dr. Matthew Lancaster and Dr. Sandra Jones from the University of Leeds found that the calcium channels weaken with age and fail. This failure is a likely factor in arrhythmia and heart attacks in elderly people. However by blocking these calcium channels in people with high blood pressure, doctors might unwittingly also be increasing the likelihood of the patients?? developing other problems including heart conditions.
Dr. Lancaster said, ??Many people suffer from an irregular heartbeat as they grow older and large numbers have pacemakers fitted. Making the link between these heart problems and the failure of the calcium channels as we age has flagged up a warning sign that some common medical treatments may be making the condition worse.?
??Clinicians should think carefully before prescribing calcium channel blockers and ensure that, in treating one heart condition, they aren??t exacerbating others,? he added. In his opinion the discovery of the link between age and loss of calcium channels opens up now avenues for treatment of heart conditions.
Dr. Jones said, ??It may be possible to mitigate the effects of the loss of calcium channels through gene therapy, as the treatment would only be required in one specific area ?? the sinoatrial node ?? so should be fairly easy to administer.?
The researchers believe exercise might also be a factor and are now looking at whether exercise training helps reduce the loss of the calcium channels in the SA node.