Combined effects of ionizing radiation and cardio-active drugs on human iPSC-derived cardiomyocytes

There are multiple cardio-active pharmaceuticals available on the market, extracting various electrophysiological effects upon the human heart. These effects are well known and well characterized [1]. However, there is virtually no information on the combined effects of applied heart pharmaceuticals in conjunction with ionizing radiation. A deeper insight in these effects, however, is of great interest for occupationally exposed groups, heart patients receiving radiation treatments, as well as astronauts. Therefore we examined the influence of X-rays on drugtreated human induced pluripotent stem cell (hiPSC)derived cardiomyocyte cultures. As a test substance isoproterenol, an analogon of the stress hormone adrenaline, was applied. The applied X-ray dose was 2 Gy. Electrophysiological parameters of the cultures were measured using microelectrode array (MEA) technology for 7 days after radiation exposure. Our results show an increase in the beat rate enhancing property of isoproterenol one day after irradiation. Direct radiation effects on the drug itself could be excluded. This poses many questions on the combined effects of ionizing radiation and stress response. Materials&Methods