There is increasing evidence of an elevated risk of adverse cardiovascular effects after an exposure to low LET radiation, typically developing with a long latency. However, much less is known about the potential cardiovascular risks associated with an exposure to high LET particles. High LET particles represent an important component of the space radiation field and thus, may affect the cardiovascular system of astronauts. Likewise, heavy ions are increasingly used in cancer therapy and the risk for long-term side effects such as radiation-induced heart disease should be assessed.
To study cardiac effects of heavy ions, we established an in vitro model system. It is based on avian cardiomyocytes isolated from embryonic chicken (stage E8). Cells are seeded onto a microelectrode array system (MEA). A MEA chip contains an array of 60 microelectrodes with a diameter of 30 µm and allows a non-invasive multi-parametric analysis of electrical endpoints such as beating frequency, arrhythmia and conduction velocity. In first experiments we examined the effects of various doses of C-ions (25-mm extended Bragg peak, LET=75 keV/um) or X-rays up to one week after exposure. The experiments revealed a high robustness of the cells to radiation injury and even after an exposure to high doses (>20 Gy) the functionality of the cells was only slightly affected. The networks remained active and uniformly contractive. Also no influence on signal amplitude and shape was observed. However, slight changes in beating rate and signal propagation were detected at higher doses. Currently, further experiments are performed to statistically verify these data.