[Effect of hypoxic preconditioning on the level of s-NGAL (lipocalin-2) in myocardial revascularization in the conditions of extracorporeal haemocirculation].

OBJECTIVE

To assess the effect of hypoxic preconditioning (HPC) on the level of s-NGAL (lipocalin-2) in myocardial revascularization under conditions of extracorporeal haemocirculation (EH).

PATIENTS AND METHODS

We examined a total of 40 patients presenting with CAD (mean age 57.62±1.20 years) and subjected to coronary artery bypass grafting (CABG) under conditions of EH. All patients were subdivided into 2 groups. The study group comprised 20 patients who during CABG were subjected to HPC, and 20 patients made up the comparison group. Preconditioning was carried out in the mode of one cycle of 10-minute hypoxemia followed by a 5-minute period of reoxygenation. All patients were subjected to measuring the concentration of lipocalin in blood serum prior to CABG and 5 hours after the beginning of the operative intervention with the help of the test system Human Lipocain-2 NGAL, ELISA.

RESULTS

Prior to operative treatment the average levels of lipocalin in blood serum of the patients of the compared groups significantly did not differ, with the inverse correlation between the levels of s-NGAL and the ejection fraction of the left ventricle (r=-0.37, p=0.02), as well as the glomerular filtration rate (according to the findings of radionuclide renoscintigraphy) and the level of lipocalin (r=-0.28, p=0.046). Five hours after the CABG, there was a statistically significant increase in the s-NGAL concentration as compared with the preoperative value both in the HPC group patients and the comparison group (from 70.65±10.72 to 127.58±22.59 ng/ml and from 65.01±8.64 to 171.65±20.10 ng/ml, respectively). There was a direct relationship between the duration of EH and the dynamics of the s-NGAL level in patients of the both groups. However, an increase in the NGAL concentration in the comparison group patients was considerably more manifested vs the study group patients (p=0.02). The median value of the difference between the pre- and postoperative values of the lipocalin level in Group I amounted to 56.94±19.76 ng/ml, being in Group II 106.64±18.94 ng/ml (p=0.004).

CONCLUSION

Hypoxic preconditioning during myocardial revascularization under the conditions of extracorporeal haemocirculation prevents a critical elevation of the lipocalin-2 level, thus suggesting a decrease in the degree of the lesion of the renal parenchyma in cardiosurgical patients.