ИСТИНА

Nowadays a number of people suffering diabetes mellitus (DM) increases rapidly due to unhealthy eating and lifestyle. DM is a group of metabolic diseases in which there are high blood sugar levels over a prolonged period. Diabetes occurs due to either the pancreas not producing enough insulin or the cells of the body not responding properly to the insulin produced. This can lead to severe alterations of vitally important systems of the organism including the cardiovascular system. Some of the major DM complications are related to the damage to blood vessels and capillaries, impairment of blood rheological properties. Aggregation is one of key factors which determining blood flow and thereby affect on blood rheology. Therefore control and monitoring the blood aggregation and disaggregation parameters which are expected to be altered in DM patients is very important. The are several instruments currently avaliable for assessment of blood aggregation. In this work we used two commercially available aggregometers – LADE-6 (RheoMedLab, Russia) and Rheoscan-D300 (Rheomeditech, Korea). Operation of these devices is based on laser aggregometry technique [1]. Laser aggregometry allows to study the kinetics of the spontaneous aggregation (time dependence of light intensity backscattered from a sample of whole blood in the rest) and shear-induced disaggregation (shear stress dependence of light intensity backscattered from a sample of whole blood under shear flow) [1]. Experiments with LADE are carried out with samples of whole blood placed in Couette chamber consisting of two coaxial glass cylinders with 1 mm gap between them. The outer glass can be rotated with high speed to produce shear flow for destroing aggregates. The obtained aggregation kinetics curves (dependance of backscattered light on time) are approximated by a sum of two exponential functions where the exponential coefficients are related to the characteristic times of linear and three-dimensional aggregates formation. Disaggregating kinetics curves (dependance of backscattered light on shear stress) are approximated by exponential function where the exponential coefficient is related to the hydrodynamic strength of aggregates. The Rheoscan operates with a disposable plastic unit having a disc-shaped sample chamber that is 4 mm in diameter and 0.3 mm hight containing a metal bar. The device have a motor that rotates a magnet beneath the sample chamber, thereby rotating the metal bar in the sample chamber to achieve disaggregation. The obtained aggregation kinetics (dependence of light transmitted through the blood sample on time) is analyzed and characteristic time of aggregation calculated. All experimental measurements were performed with human blood samples drawn from patients with diabetes milletus (N=10) and without (N=8) as well as with rat blood drawn from healthy animals (N=10) and from rats with experimentally induced DM (N=10). All blood samples were stabilized with EDTA to prevent blood clotting. The experimental results obtained using LADE shows that DM is characterized by about 30% increase in time of the formation of linear aggregates that, however, have close to normal hydrodynamic strength. Time of 3D aggregates formation decreases by about 10-25 % in comparison with that in the control group. Alterations of the related parameters obtained with Rheoscan are quantitatively different and more pronounced. These differences are discussed.