Journal of applied physiology
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Isolated perfused lung systems are commonly used to assess lung function in experimental studies. Assessment of hemodynamics and gas-exchange function in these systems is limited by the availability of venous blood. This study describes and validates a rat lung perfusion circuit in which a double-lung block ventilated with a hypoxic gas mixture [inspired O2 fraction (FIO2) 0.04; inspired CO2 fraction 0.08; deoxygenator (Deoxy) block] is used to provide blood with blood gases that are similar to mixed venous values to perfuse a study lung (FIO2 0.21; left lung only). ⋯ Finally, in protocol 4, perfusion of a damaged study lung did not impair the function of the system. We conclude that this model permits reliable assessment of pulmonary function in rats under controlled ventilation and perfusion conditions. The use of a Deoxy double-lung block simplifies the perfusion apparatus and eliminates the main cause of instability of other systems that use an anesthetized host animal to provide venous blood.
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The study's objective was to determine whether estradiol (E2) deficiency alters the functional relationship of muscle to bone and causes a differential increase in injury susceptibility. Ovariectomized 6-wk-old mice were administered E2 (40 micrograms. day-1. kg-1; n = 8) or the oil vehicle (n = 8) for 21 days. The anterior crural muscles of the left hindlimb were then stimulated to produce 150 maximal in vivo eccentric contractions. ⋯ In fact, the decrement in P(0) was only 36.9 +/- 3.8% in exercised EDL muscles from E2-deficient mice compared with 50.6 +/- 4.2% in exercised muscles from E2-treated mice (P = 0.03). Tibia stiffness was 3.9% higher in bones from exercised legs than in bones from unexercised legs (72.64 +/- 2.77 vs. 69.95 +/- 2.66 N/mm; P = 0.05) with ultimate load showing a similar trend (P = 0.07); no effect of E2 status was observed on these differences (P > or = 0.53). In conclusion, the functional relationship of bone to muscle and the susceptibility to injury in bone are not altered by the presence of E2 in ovariectomized mice; however, E2 does increase injury susceptibility in the EDL muscle.