[Impact of simulated microgravity on the expression and distribution of cardiac gap junction protein CX43]

To observe the expression and distribution changes of connexin 43 (CX) in rats' myocardium after simulated microgravity and explore the partial mechanism of arrhythmia.

Male Wistar rats were randomly assigned to either tail-suspension group (SUS) or control group (CON). Immunohistochemistry and Western Blot were used to detect the expression and the distribution of CX43. Electromicroscope was used to observe the ultrastructural changes.

In SUS group, the decrease of CX43 and the distribution disturbance were obvious (P<0.05), the proportion of the side-to-side gap junction increased (P<0.05), and space between some gap junctions disappeared.

The results show that CX43 decreased significantly and distributed irregularly after simulated microgravity. These can cause the changes of cardiac electric conduction velocity and direction. As a result, conduction block and reentry may occur. And these might be the partial mechanism of cardiac arrhythmia.