Differential effects of xanthine oxidase inhibition and exercise on albumin concentration in rat tissues.

Albumin is a protein present in almost all kinds of mammalian cells. It has binding sites for several molecules, and possesses antioxidant and other important properties. The aim of this study was to examine the effects of 2 different oxidative stress stimuli - exercise and allopurinol administration - and their combination on albumin concentration in several rat tissues. Samples of soleus, extensor digitorum longus (EDL), and gastrocnemius muscles, and the liver and heart were collected before, immediately after, and 5 h after exercise, and collected at the respective time points after allopurinol administration. Albumin dimmers, markers of oxidative stress, were also assessed in EDL muscle. Albumin concentration increased in the skeletal muscles examined, whereas it decreased in the heart and remained unaffected in the liver after exercise. Allopurinol alone did not affect albumin concentration in any of the tissues. Albumin concentration increased in soleus and EDL muscles, decreased in gastrocnemius muscle and the liver, and remained unaffected in the heart after exercise and allopurinol combination. Albumin dimmers also increased postexercise in EDL muscle. Our findings suggest that the increase in albumin concentration in skeletal muscles may be an antioxidant mechanism response, but may depend on the type of oxidative stress and be stimulation- and tissue-specific.