Antithrombin III Activity and Concentration in Diabetes Mellitus

Diabetes mellitus: a hypercoagulable state

Eighty percent of patients with diabetes mellitus die a thrombotic death. Seventy-five percent of these deaths is due to cardiovascular complications, and the remainder is due to cerebrovascular events and peripheral vascular complications. Vascular endothelium, the primary defense against thrombosis, is abnormal in diabetes. Endothelial abnormalities undoubtedly play a role in the enhanced activation of platelets and clotting factors seen in diabetes. Coagulation activation markers, such as prothrombin activation fragment 1+2 and thrombin-anti-thrombin complexes, are elevated in diabetes. The plasma levels of many clotting factors including fibrinogen, factor VII, factor VIII, factor XI, factor XII, kallikrein, and von Willebrand factor are elevated in diabetes. Conversely, the level of the anticoagulant protein C (PC) is decreased. The fibrinolytic system, the primary means of removing clots, is relatively inhibited in diabetes due to abnormal clot structures that are more resistant to degradation and an increase in plasminogen activator inhibitor type 1 (PAI-1). Increased circulating platelet aggregates, increased platelet aggregation in response to platelet agonists, increased platelet contractile force (PCF), and the presence of higher plasma levels of platelet release products, such as beta-thromboglobulin, platelet factor 4, and thromboxane B(2), demonstrate platelet hyperactivity in diabetes. This constellation of findings supports the clinical observation that diabetes is a hypercoagulable state. This article briefly reviews the published evidence for this conclusion and the putative roles played by hyperglycemia and hyperinsulinemia in its development.

Physiological inhibitors of blood coagulation and prothrombin fragment F 1 + 2 in type 2 diabetic patients with normoalbuminuria and incipient nephropathy

Microalbuminuria and haemostasis derangements have been considered as independent risk factors for cardiovascular death in type 2 (non-insulin-dependent) diabetic patients. Few studies have assessed coagulation inhibitors in type 2 diabetic patients with normoalbuminuria and microalbuminuria. Therefore, 32 type 2 diabetic patients with normoalbuminuria (albumin excretion rate, AER < 20 mg/min, mean 7 +/- 1) and 28 type 2 diabetic patients with microalbuminuria (AER 20-200 mg/min, mean 84 +/- 11) were studied. The patients were matched for age, sex, disease duration and treatment, body mass index (BMI), blood pressure and glycohaemoglobin. Protein C and S activity, antithrombin III, thrombomodulin and prothrombin fragments 1 + 2 (F 1 + 2) were assessed together with fibrinogen, triglycerides, total and high density lipoprotein (HDL)-cholesterol concentrations. Fibrinogen, total and low density lipoprotein (LDL) concentrations were similar in the two groups, while a significant difference was observed for triglycerides (normoalbuminuric group: 128 +/- 10 mg/dl, microalbuminuric group: 184.1 +/- 17 mg/dl; P < 0.007) and HDL-cholesterol (normoalbuminuric group: 45 +/- 2 mg/dl, microalbuminuric group: 39 +/- 2 mg/dl; P < 0.05). The coagulation parameters were as follows: normoalbuminuric group: protein C activity 109% +/- 5%, protein S 95.4% +/- 5%, thrombomodulin 49.3 +/- 3 ng/ml, antithrombin III 93.3% +/- 3%, F 1 + 2 1.05 +/- 0.04 nmol/l; microalbuminuric group: protein C activity 107% +/- 4%, protein S 98.4% +/- 4%, thrombomodulin 64.4 +/- 4 ng/ml, antithrombin III 93.3% +/- 3%, F 1 + 2 1.03 +/- 0.05 nmol/l. The difference was significant for thrombomodulin (P < 0.007). A significant direct correlation was observed in the microalbuminuric group between AER and thrombomodulin (r = 0.38, P < 0.05). In conclusion, our data do not support the hypothesis that a reduction in the activity of anticoagulant physiological inhibitors (protein C, protein S, antithrombin III) could contribute to explain the higher cardiovascular risk in type 2 diabetic patients with microalbuminuria. The elevation of plasma thrombomodulin concentration in type 2 diabetic patients could be the consequence of widespread vascular damage in diabetic patients with incipient nephropathy.

Platelet-dependent thrombin generation in patients with diabetes mellitus: effects of glycemic control on coagulability in diabetes

OBJECTIVES

This study sought to assess the usefulness of platelet-dependent thrombin generation as an index of coagulability in diabetes and to determine the effect of glycemic control on coagulability in diabetes.

BACKGROUND

It is important to investigate the interaction of platelets and the coagulation factors to clarify the processes of the coagulation system in detail.

METHODS

Platelet-rich plasma (150 X 10(9)/liter), 0.5 ml, was prepared, and 40 mmol/liter of calcium chloride was added to initiate clotting. S-2238 was added to each sample in a microtiter plate every 10 min, and the absorbance of the released color product at 2 min was measured spectrophotometrically at a wavelength of 405 nm using a microtiter plate reader as thrombin generation. We measured the platelet-independent thrombin generation in patients with non-insulin-dependent diabetes mellitus grouped according to glycemic control.

RESULTS

Platelet-dependent thrombin generation at 30 min after calcium chloride addition was significantly higher in 23 patients with poorly glycemic-controlled non-insulin-dependent diabetes mellitus without complications, such as diabetic retinopathy, nephropathy and neuropathy (hemoglobin [Hb] A1c >/= 9.0%) than in 46 healthy normal subjects (448 +/- 75 vs. 165 +/- 28 mU/min, p < 0.001). Thrombin generation in 31 well controlled diabetic patients without complications (Hb A1c < 9.0%) was intermediate (240 +/- 72 mU/min) between those of the poorly controlled group and healthy normal subjects. Platelet-poor plasma from diabetic patients increased platelet-dependent thrombin generation in normal subjects.

CONCLUSIONS

Coagulability is evidently enhanced in patients with non-insulin-dependent diabetes mellitus compared with that in healthy normal subjects on the basis of assessments of the platelet-dependent thrombin generation, and good glycemic control may help to correct a hypercoagulable state in diabetic patients.

Antithrombin III stimulates prostacyclin production by cultured aortic endothelial cells

Prostacyclin (PGI2) is a potent vasodilator and an inhibitor of platelet aggregation. We found that antithrombin III (AT III), an anticoagulant present in circulating blood, stimulated PGI2 production by cultured bovine aortic endothelial cells in a dose- and time-dependent manner. The stimulation of PGI2 production by AT III was observed at physiological concentrations and was inhibited by the addition of anti-AT III antiserum and heparin. These results suggest that AT III may stimulate PGI2 production by binding to heparin-like molecules on the endothelial cell membrane.

A comparison of two anesthetic techniques for the study of rat skeletal muscle high-energy phosphates in vivo using 31P-NMR

31P-Nuclear magnetic resonance (NMR) spectroscopy was used to evaluate in vivo rat quadriceps ATP, phosphocreatine (PCr), inorganic phosphate (Pi) and tissue pH during anesthesia with ketamine/xylazine (K/X) or isoflurane (IS). A surface coil was used to receive signals from the quadriceps muscle of rats positioned in a wide-bore horizontal magnet. The PCr/beta-ATP ratios determined from the NMR spectra were 4.34 +/- 0.19 (K/X) and 4.40 +/- 0.28 (IS). Tissue pH was 7.09 +/- 0.05 (K/X) and 7.13 +/- 0.07 (IS). Metabolic stability of quadriceps PCr and ATP was demonstrated during both K/X and IS anesthesia, but the K/X-anesthetized animals had longer sleep time, lower food consumption, and lower body weight post-anesthesia than the IS-anesthetized animals. The PCr/beta-ATP ratio in quadriceps of repetitively IS-anesthetized rats did not fluctuate diurnally. In addition, the animals recovered rapidly and continued to gain weight following the multiple brief IS anesthetic procedures. These data indicate that serial in vivo investigations of high-energy-phosphate metabolism in small animals can be accomplished using 31P-NMR spectroscopy and IS anesthesia, which has several advantages over K/X anesthesia for these types of studies.