Maya Mantskava, Nana Momtselidze,  Nugzar Pargalava, George Mchedlishvili.

Microcirculation Research Center, I. Beritashvili Institure of Physiology, 14 Gotua St., 0160, Tbilisi, Georgia
N. Bochua Center of Angiology and Vascular Surgery, 1. Chachava St., 0159, Tbilisi, Georgia

Abstract. The aim of the present study was to evaluate blood rheological disorders, in particular RBC enhanced aggregation, and compare changes in these parameters in patients with type I and II diabetes mellitus. For evaluation of RBC aggregability in the present study we applied the “Georgian technique”, which was developed and applied for several years in our laboratory. Its advantage is that it is a direct and quantitative method. In all the investigated patients, diabetes mellitus was compared with the foot gangrenes. The patients were divided into two groups: (a) with type I and with type II diabetes mellitus. We matched the RBC aggregability indices in both groups of diabetic patients and compared the obtained results with those in the healthy control group. We found that rheological disorders were considerably pronounced.

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The RBC aggregability index increased by 62 per cent (p<0.001) in type I and by 57 per cent (p<0.001) in type II diabetic patients as compared to the control group. However, there were insignificant differences of the RBC aggregability changes between the two groups of the patients. Therefore we conclude that blood rheological disorders are similar in both types of diabetes mellitus. The disturbed blood fluidity related to the increased RBC aggregability in the microcirculation promotes, in particular, the development of the gangrene in both types of diabetes mellitus.Text[/su_animate]

1. Introduction

Blood rheological disorders ply an essential role in the pathogenesis of most complications of the diabetes mellitus (retinopathy, nephroangiopathy, and the microangiopathy of lower extremities). One of the most wide-spread complications of type I and II diabetes mellitus are the microangiopathies of the lower extremities: 19 per cent of all diabetic patients suffer from these pathologies.
H\The hemorheological properties (RBC aggregation, their deformation, blood plasma viscosity and hematocrit) play an important role just in the smallest blood vessels, whose diameters are commensurable with the red blood cells. For appraisal of the hemorheological disorders in patients with type I and II diabetes, we have investigated the RBC aggregability index that is certainly the most significant blood rheological property of the microcirculation.

2. Material and methods

A total of 11 patients with type I diabetes (mean age 42±18) and 18 patients with type II diabetes (mean age 53±21) were examined in the present study. The acute form of microangiography with accompanying foot gangrene was investigated in all patients. 25 healthy subjects, aged 48±12 years, served as the control group. In order to assess the hemorheological disorders in patients with types I and II diabetes, we studied the index of the erythrocyte aggregability.
The erythrocyte aggregability index, which is an expression of the relationship between the aggregated and unaggregated red blood cells, was evaluated using the “Georgian technique” [7]. Blood samples 94 ml) were centrifuged 3000 g during 15 minutes. Then, about 0.1 ml of the blood was diluted 1:200 in the patient’s plasma in a Thoma pipette preliminary rinsed with 5% sodium citrate su\olution without addition of any anticoagulants to the blood under study. Following standard mixing, the diluting blood was placed into a glass chamber 0.1 mm high. The quantitative index of erythrocyte aggregability was assessed with a special program at the texture analysis system (TAS-plus, LEITZ, Germany), which was composed of the microscope “Ortoplan” (x630), micro-video recording camera, Computer “PD P-II”, Display “PT II SJ” and printer.
The data presented below are arithmetic means and their standard deviations. The difference were considered significant when P<0.001.

3. Results

The date obtained show that in the group of diabetic patients with type I diabetes, with foot gangrene, the average index of the erythrocyte agregability was significantly higher 49.8± 8.2 as compared to the control group (the index equaled 29.4±5,6) (two-sample T-test p<0.001). On the other group of patients with type I diabetes with foot gangrene, an average index of the erythrocyte aggregability increased 47.2±6.8 as compared to the control group (Two-Sample T-test p<0.001). These data indicate that the erythrocyte aggregability index in the group of patients with type I of diabetes was higher than in the control groups (Fig.1), as well as in type II diabetes mellitus (Fig.2).

4. Discussion

Notwithstandading the different mechanisms of type I and type II diabetes development, the microangiopathies are characteristics of both types of diabetes. The diabetic microangiopathies are characterized by development of atherosclerotic plaques on the intima of arteries. These plaques may be calcified and uncerated, hence promoting occurrence of local thrombosis and occlusion of the vessels lumen [2]. However, there are authors who suggested that the diabetic pathologies appear as a result of the hemorheological disorders [2.3], i.e., that blood rheological disorders are one of the most significant factors that lead to the appearance of diabetic microangiopathies [1]. Therefors, it was essential to investigate RBC aggregability in patients with diabetic microangiopsthies.
Increase of the erythrocyte aggregability in the blood of patients with foot diabetic gangrene can be explaned by high plasma glucose levels. In a hypothesis of the mechanism of RBC aggregability mechanism, the pronounced changes of blood plasma osmolarity induce the release of colloids from the inter-erythrocyte spaces, which carry out water, as a result of which splicing of the erythrocytes does occur [8]. Other investigators explain these mechanisms in the following way: if the polymers, contacting with the erythrocytes, lose their configuration entropy, which mean while is not balanced with adsorption energy, a medium with lesser concentration of polymers than in the plasma develops between two erythrocytes [4]. It should be noted as well

That during diabetic microangiopathies, especially when there are lesions in the lower extremities, the pH does increase and the latter entails increased RBC aggregability [5]. The data ibtained document that, independently of the diabetes type, in presence of foot gangrene, aggregability of the erythrocytes increases significantly, as compared to the normal values. In order to verify this notion we carried out in vitro experiments [6]. Into the vial with the blood of healthy subjects glucose was added and an index of the erythrocyte aggregability was measured. The RBC aggregability was increased sharply, therefore documenting that excessive volume of glucose entails increase in the erythrocyte aggregability in both type I and type II diabetes.

References

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[2] M. Balabolkin. Endocrinology, Yaroslavl, 1997.
[3] A.L. Coply Hemorheologic therapy to control diabetic vascular disease. Clinical Hemorheology 12 (1992), 787-796.
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[5] N. Maeda, M. Seiko, Y, Suzuki and T. Shiga. Effect of pH on the velocity of erythrocyte aggregation. Biorheology 25 (1998), 25-30.
[6] M.Mantskava. Analysis of microcirculation and microrheology during some peripheral microangiopathy. PhD Dissertation, Microcirculation Research Center, I. Beritashvili Institute of physiology, Georgia,2004.
[7] G. Mchedlishvili, N.Beritashvili, D. Lominadze, B. Tsinamdzgvrishvili.. Technique for direct and quantitative evaluation of erythrocyte aggregability in blood samples. Biorheology. 30, (1993), 153-161.
[8] B. Neu and H.J. Meiselman. Depletion-mediated red blood cell aggregation in polymer solutions, Biophysics 83 (2002)2482-2490.