Enzyme Changes in Rat Liver After Space Flight
- Paper number
IAC-06-A1.2.09
- Author
Dr. Peter Stein, University of Medicine and Dentistry of New Jersey, United States
- Year
2006
- Abstract
Baldwin et al. reported that in space flown rats there was a decrease in the ability of the soleus muscle to oxidize long chain fatty acids after space flight. Other studies have shown that that disuse atrophy I associated with an increased reliance on glucose for energy. We subsequently showed in a ground based HLS study that these changes were accompanied by increases in glucose synthetic potential in rat liver (J. Nutr. Biochem. 16: 9-16, 2005). Specifically there were increases in the activities of three of the four enzymes involved in the regulation of the gluconeogenesis pathway. The same measurements were made for the 5 flight (FL) and 5 ground control rats. Results (control, HLS/FL). Units are µmole. min-1.mg protein-1. Pyruvate carboxylase (HLS 0.35 + 0.02 vs 0.36 + 0.02, p=ns p=ns; FL 0.38 + 0.02 vs 0.37 + 0.02, p=ns), phosphoenolpyruvate carboxykinase (HLS 0.031 + 0.002 vs 0.038 + 0.012, p<0.05); FL 0.030 + 0.003 vs 0.050 + 0.002 (p<0.05); glucose-6-phosphatase (0.14 + 0.01 vs 0.17 + 0.01 p<0.05; FL 0.14 + 0.01 vs 0.14 + 0.02 p=ns); Fructose 1,6, Bisphophosphatase (0.048 + 0.002 vs 0.054 + 0.002, p<0.07; 0.035 + 0.005 vs 0.042 + 0.006, p=ns). In addition liver glycogen was depleted for both HLS and flight rats. HLS 151 + 14 vs 105 + 15; flight, 211 +31 vs 136 + 42. Units are mg-1.kg.wet wt-1. Although the number of flight rates (and controls) is small, similar responses were found wit FL as with HLS. Conclusions: Liver carbohydrate metabolism responses to HLS and space flight are similar.
- Abstract document