Background & Objective: Endurance activity and "mediator complex subunit 13" significantly influence on structure and tissue of heart. The purpose of this study was to investigate the effects of a long time endurance activity program on "mediator complex subunit 13" gene expression in the left ventricle.

Materials and Methods: 14 rats under controlled conditions were housed and after familiarization randomly were assigned into control and Experimental groups, the experimental group performed an endurance activity program (14 weeks) on motorized treadmill, and then 48 hours after the end of the last session were anesthetized and sacrificed. The left ventricle of the heart was removed. Real time RT-PCR method was used to determine the expression levels of "mediator complex subunit 13" gene in the left ventricle. Finally t-test was used to evaluate collected data.

Results: The results of this research showed, physical activity not only influences on heart weight indices, but also it enhances "mediator complex subunit 13"gene expression in left ventricle of trained rats.

Conclusions: Given to the effects of endurance activity on the size of left ventricle and its indices, it seems part of these effects were related to "mediator complex subunit 13" gene expression.

Keyword:"mediator complex subunit 13"gene, endurance activity, left ventricle