Association of endothelial nitric oxide synthase gene G894T polymorphism with blood oxygen transport.

Background: Nitric oxide (NO) is involved in formation of oxygen transport function of blood and oxygen transport in tissues by means of interaction with haemoglobin. Endothelial nitric oxide synthase gene G894T polymorphism affects the expression and the activity of the NO synthase enzyme. The influence of this polymorphism on the formation of oxygen-dependent processes in the body has not been completely investigated.

Objective: To evaluate the associations between G894T polymorphism of the endothelial nitric oxide synthase gene and the condition of oxygen transport function of blood in healthy male volunteers.

Methods: The study subjects were healthy young males aged 18-24 years (n = 165). The blood was drawn from the cubital vein at rest after 12 h following the last food intake. G984T polymorphism and the blood oxygen indices pO, CvO, SO, pH, р50 (the temperature was 37°С, рН = 7.4, рСО = 40 mm Hg) and р50 (actual temperature, рН and рСО), etc. were determined.

Results: In persons with the TT-genotype, the oxygen content in venous blood was 48.7% (q = 0.019) lower compared to subjects with the GT-genotype and 49.4% (q = 0.019) lower compared to subjects with the GG-genotype. The saturation of blood in carriers of the TT-genotype was 32.4% (q = 0.021) and 35.9% (q = 0.019) lower as opposed to subjects with the GT-genotype and the GG-genotype, respectively. In blood of subjects with the TT-genotype, the oxygen tension was 26.1% (q = 0.019) lower as compared to subjects with the GT-genotype and 27.4% (q = 0.019) lower as opposed to the GG-genotype. In turn, volunteers having a common allele in their genotype (GG + GT) demonstrated oxygen tension to be 26.7% (q = 0.019) higher compared to subjects with the TT-genotype. The blood pH values of the subjects having the recessive genotype were 0.022 units lower compared to the GG (q = 0.044) and GT (q = 0.042) genotypes. In volunteers with the TT-genotype, the p50 parameter was 5.8% (q = 0.027) lower compared to subjects with the GT-genotype and 6.8% (q = 0.019) lower compared to volunteers with the GG-genotype. In persons with two T-alleles in their genotype, p50 was 5.4% (q = 0.019) lower compared to subjects with the GT-genotype and 6.4% (q = 0.019) lower compared to persons with the GG-genotype.

Conclusion: The T-allele of G894T polymorphism is associated with low values for oxygen content, oxygen tension, acidic pH shift and increased haemoglobin affinity for oxygen under standard and real conditions. The presence of a minor allele in G894T polymorphism of the NOS3 gene contributes to formation of oxygen transport function of blood.