Modified gravitational field and lactate dehydrogenase activity

Area of Science:

• Physiology
• Biochemistry
• Space Medicine

Background:

• Gravitational changes, such as reduced muscle activity (hypokinesia) or increased force (centrifugation), can impact physiological processes.
• Lactate dehydrogenase (LDH) is an enzyme crucial for energy metabolism, and its isoenzyme activity can indicate tissue stress or damage.

Purpose of the Study:

• To investigate the effects of altered gravitational environments on lactate dehydrogenase (LDH) activity and isoenzyme distribution in rats.
• To compare the impact of hypokinesia versus centrifugation on LDH activity.

Main Methods:

• Rats were subjected to either hypokinesia (reduced muscle solicitation) or centrifugation (increased gravitational solicitation) for 7 days.
• Lactate dehydrogenase (LDH) activity and its isoenzyme profile (LDH1-5) were analyzed in serum and myocardium.

Main Results:

• Hypokinesia significantly elevated LDH5 isoenzyme activity by 40% in serum and 30% in myocardium compared to controls.
• Centrifugation resulted in a smaller increase in LDH5 activity, 20% in serum and 18% in myocardium.
• All LDH1-5 isoenzymes were present in the cardiac muscle of all groups, while serum primarily showed LDH2 and LDH5.

Conclusions:

• Altered gravitational conditions significantly affect lactate dehydrogenase (LDH) activity, particularly the LDH5 isoenzyme.
• Hypokinesia appears to induce a more pronounced elevation in LDH5 activity compared to centrifugation.
• LDH isoenzyme analysis can serve as a biomarker for physiological responses to gravitational stress.