Effects of dopamine and dobutamine on skeletal muscle oxygenation in normoxemic rats

The effects of two vasoactive drugs, dopamine and dobutamine, on skeletal muscle tissue oxygenation were studied in a normoxemic rat model. It is usually claimed that drugs may increase or decrease oxygen delivery to tissues. However, this claim is only valid on the global level. Our interest is directed towards individual organs. Two groups of rats (n = 7 each) were studied. One group received dopamine, the other dobutamine. Blood gases, hematocrits, and mean arterial blood pressures were measured in addition to tissue pO2. Infusion of dopamine 2.5 micrograms/kg/min resulted in a statistically significant decrease in skeletal muscle pO2. Higher doses of dopamine, and all doses of dobutamine, did not influence pO2 at all. The results raise the question of whether blood flow to vital organs may be negatively affected by dopamine 2.5 micrograms/kg/min. Direct measurements of tissue oxygenation are warranted in, e.g., the liver and gut.