Some effects of reserpine and hydraliazine upon tissue respiration and the concentration of adenosine nucleotides in certain tissues.

The effects of reserpine and hydrallazine upon the oxygen uptake of preparations of rat brain, liver, and kidney and rabbit aorta have been investigated using the Warburg "Direct" method. In these tissues reserpine did not significantly stimulate respiration at any of the doses used. Concentrations of 10 or 50 mug./ml. had no significant effect upon respiration, but higher doses (330 mug./ml.) depressed it in all the tissues studied. This effect was also seen in rat brain at a reserpine concentration of 100 mug./ml. which had no significant effect in other tissues. Hydrallazine (50 or 100 mug./ml.) depressed respiration in all tissues studied. Stimulation at lower doses was not seen.After sublethal doses of reserpine, depletion of energy rich phosphate compounds occurred in brain and liver but not in skeletal muscle and heart. Hydrallazine also depleted brain of energy rich phosphate compounds, but did not affect liver, heart, or skeletal muscle. The bearing of these results on the mode of action of reserpine and hydrallazine is discussed.