London, July 14 (IANS): Even low exposure to ionising radiation, such as X-rays, may increase the risk of cardiovascular diseases, a study has cautioned.

The findings indicated that an individuals' exposure to X-rays, even at around 0.5 Gy -- which is equivalent to recurrent CT scan imaging -- is associated with a significantly increased risk of cardiovascular damage, up to decades after exposure. 

Further, exposure to X-rays also caused several other permanent alterations in the human coronary artery endothelial cells that had the potential to adversely affect their essential functions.

Endothelial cells, which form the inner layer of blood vessels, were found to produce reduced amounts of nitric oxide -- an essential molecule in several physiological processes including vascular contraction. 

This raises questions about the nature of long-term alterations in the heart's vascular system caused by such doses, said Soile Tapio from Helmholtz Zentrum Munchen, the German Research Centre for Environmental Health.

The results were published in the International Journal of Radiation Biology. 

Cells damaged by low-dose radiation also produced increased amounts of reactive oxygen species (ROS), leading to damage in DNA and proteins.

In addition, the exposed cardiac endothelial cells were found to have reduced capacity to degrade oxidised proteins and to be ageing prematurely. 

All these molecular changes are indicative of long-term premature dysfunction and suggest a mechanistic explanation to the epidemiological data showing increased risk of cardiovascular disease after low-dose radiation exposure, Tapio said.