Treadmill Exercise In Rats Research Articles

Pulmonary gas exchange during hypoxic exercise in the rat

Pulmonary gas exchange and O 2 transport were studied at rest and during maximal treadmill exercise in rats in acute hypoxia ( Pi O 2 ∼71 Torr ), and in littermates acclimatized to Pb = 380 Torr ( Pi O 2∼71 Torr ) for 3 weeks (chronic hypoxia). to obtain valid estimates of blood gas partial pressures, particularly during exercise, the temperature coefficients of blood pH, P O 2 and P CO 2 were determined (Appendix). In both acute and chronic hpoxia, the following changes were observed: alveolar adn arterial P O 2 increased considerably, but the difference, A-aP O 2 , did not change significantly; arterial O 2 concentration (Ca O 2 ) decreased, and apparent pulmonary diffusing capacity for O 2, D app, increased. The increase in D app, together with hyperventilation, may prevent further drop in Ca O 2 due to a large rightward shift in the blood-O 2 equilibrium curve caused by lactic acidosis in conjunction with a large Bohr coefficinet characteristic of this species. Comparison with corresponding results obtained in man reveals that during hypoxic exercise, the rat shows a larger increase in Pa O 2 , an increase, instead of a decrease, in Pa O 2 , and a larger increase in D app.

AMP deaminase binding in rat skeletal muscle after high-intensity running.

Skeletal muscle deaminates a substantial fraction of its adenylate pool to inosine 5'-monophosphate (IMP) when the rate of energy expenditure exceeds supply. How AMP deaminase is activated in vivo is unclear because the substrate affinity is quite low (Michaelis constant approximately 1-2 mM) relative to estimated concentrations of free AMP in skeletal muscle (0.2-1 microM). AMP deaminase:myosin binding causes a large increase in substrate affinity; whether this binding occurs during physiological exercise is uncertain. Exhaustive high-speed (60 m/min) treadmill exercise in rats results in an extensive depletion of adenine nucleotide and a stoichiometric accumulation of IMP (1.5-2 mumol/g) in the superficial vastus lateralis muscles (predominantly fast-twitch white). We measured AMP deaminase:myosin binding after intense exercise and found the bound fraction of AMP deaminase to be increased from 9 +/- 1% at rest to 48 +/- 4% at approximately 45 s after exercise. The extent of binding lessened during recovery from exercise, falling to 32 +/- 4% after approximately 75 s and 21 +/- 2% after approximately 105 s. This postexercise dissociation of AMP deaminase from myosin appeared to be a first-order process (approximately 50 s half time). Treadmill running that leads to deamination also results in AMP deaminase:myosin binding. Binding should activate AMP deaminase and thus favor IMP formation at low physiological concentrations of AMP.

Cardiovascular responses to treadmill exercise in rats: effects of training.

Cardiovascular responses to treadmill exercise in rats: effects of training.