Scintigraphic demonstration of exercise-induced changes in the distribution in vivo of indium-111-labelled platelets

The origin of platelets released in response to physical exercise, especially with regard to the magnitude and nature of the nonsplenic platelet pool, is studied, using indium-111 labeled platelets in seven healthy males. A considerable variability exists as to the mechanism of platelet release into the peripheral blood in response to physical exercise. In most cases the spleen is the dominating platelet-releasing organ, but very often the liver and to a lesser degree the lungs participate in platelet release. The bone marrow may play an additional role in some cases