engleski

Blood cell concentrations in response to simulated breath-hold diving in humans.

Human spleen sequestrate 200-250 ml of densely packed blood cells, of which up to 50% is ejected to systemic circulation during strenuous exercise or apneic diving. The contribution of splenic contraction following repeated breath-hold apneas to observed changes in erythrocyte, leucocyte and platelet blood concentration remains elusive. Measurement of blood cells concentration in venous blood, as well as noninvasive cardiopulmonary parameters, were performed in 18 trained apnea divers, 18 control subjects, and 7 splenectomized men. They performed 5 successive maximal apneas with face immersion in cold water. Breath-holds were separated with 2 minutes intervals allowing for withdrawal of venous blood samples, which were also taken 10, 20, 40, and 60 minutes after the last apnea. Significant increases in erythrocyte and leucocyte concentrations in venous blood were observed immediately following the repeated apneas in trained divers and control subjects, whereas splenectomized subjects showed no change in erythrocyte concentration, and only small and gradual increase in leucocyte concentration. Platelet concentration in systemic venous blood showed no change in any group investigated. The well-known diving responses (bradycardia, elevated blood pressure) were observed in all subjects. We conclude that breath-hold induced splenic contraction produces increase in erythrocyte and leucocyte concentrations in venous blood, and causes no change in platelet concentration. Supported by Croatian Ministry of Science, Education and Sport

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