American scientists simulated conditions of long-duration space flight on rats and found that radiation exposure leads to the development of perivascular heart fibrosis. It was also discovered that this effect occurs independently of microgravity's influence.
The study showed that microgravity itself affects immune cells and the cytokine secretion process. However, neither radiation nor microgravity alone, nor their combined effect, influences the maintenance of calcium homeostasis.
The results of this work were published in the scientific journal PLoS One.