Energy economy of human uterine muscle strips under different in vitro conditions and its dependence on tissue redox potential

Objective: To study the energy economy of human myometrium in vitro. Study design: Myometric biopsies were kept for 10 min or 4 h in a buffer solution at +4°C before preparation into ‘early’ and ‘late’ strips, respectively. The strips were perifused at +37°C for different periods of time. Adenylates, energy charge (EC), adenosine and NAD + were determined in individual strips. Results: Mean EC and ATP values were low, the ‘late’ strips displaying 5% and 20% lower values than the ‘early’ strips, respectively. During perifusion the EC increased slightly, ADP decreased significantly and the strips began to contract. A correlation fitting a multiplicative function was evident between EC and NAD + ( r = 0.89, P < 0.001). Conclusion: Human myometrium, being operative at an unusually low EC level, maintained its energy economizing and contractile functions in vitro for 4 h, displaying a tight relationship between EC and NAD +, suggestive of a compromised energy balance.