Total DNA and protein content of human skeletal muscle and adipose tissue.

The research into human adipose tissue has significantly lagged behind skeletal muscle in the field of exercise physiology. It was the emergence of tissue crosstalk that resulted in adipose tissue becoming more relevant to the understanding of exercise responses and adaptations (1, 8, 80, 83, 115). One way to gain insight into the biology of these tissues before, during and after exercise is profiling the expression of biomolecules, such as DNA and protein. To do this, the DNA and protein contents of the tissues must be known to guide downstream assays. These have been established for skeletal muscle but remain relatively unknown for adipose tissue. The goal of this project was to determine a basic profile of DNA and protein contents of human adipose tissue and compare them to those of skeletal muscle. Basal skeletal muscle and adipose tissue samples were obtained from 10 (7M, 3F) recreationally active participants (25 ± 1 y; VO2max: 3.49 ± 0.19 L·min-1). DNA and protein were extracted and then analyzed for quantity. The DNA content of adipose tissue averaged 52 ± 4 ng DNA·mg tissue-1 and ranged from 29 to 79 ng DNA·mg tissue-1, while muscle averaged 189 ± 14 ng DNA·mg tissue-1 and ranged from 95 to 250 ng DNA·mg tissue-1. The protein content of adipose tissue averaged 4 ± 0 µg protein·mg tissue-1 and ranged from 3 to 5 µg protein·mg tissue-1, while muscle averaged 177 ± 3 µg protein·mg-1 and ranged from 161 to 187 µg protein·mg tissue-1. The primary finding was that skeletal muscle had 3.6x more DNA per mg of tissue than adipose, and 44x more protein per mg of tissue than adipose. This study provides a basic profile of human adipose and skeletal muscle tissue DNA and protein contents, information that is necessary for guidance of future studies.