Local haemorheological changes and intracellular erythrocyte Ca++ content in exercising ischaemic limb

Abstract

In patients affected by Peripheral Obliterative Arterial Disease (POAD), an increase of blood viscosity was observed in basal conditions in blood samples collected from brachial veins. To investigate the role of regional haemorheological changes in venous and arterial blood during isotonic exercise, an experimental model was set up in POAD patients. The exercise was performed on a pedal ergometer with a dynamic brake until the onset of limb claudication. The evaluation of haemorheological parameters in femoral artery, in femoral vein and in brachial vein was performed before and after the exercise. Whole blood viscosity at various shear rates, whole blood filterability were controlled and correlated to the variations of oxygen transfer, of acid-base equilibrium, of lactic acid production, of fibrinolysis and of biological markers of platelet and leukocyte activation (beta-thromboglobulin and lactoferrin) in sample coming from regional artery and vein and from systemic vein. The results confirmed that the exercise induced an impairment on local blood fluidity with simultaneous reduction of venous pO2 and increase of lactic acid production. Beta-thromboglobulin and lactoferrin increased to indicate the activation of platelets and leukocytes; also an increase of the fibrinolysis was observed. Subsequently, on the same experimental model, also the role of intracellular Ca++ content of blood cells was investigated. The results seems to show that, after exercise, the intraerythrocytary Ca++ content increases. Considering that Ca++ plays an important role on cell membrane fluidity, the worsening of blood viscosity could be explained also by reduction of red cell deformability due to the increased Ca++ in the erythrocytes.