The G894T Polymorphism of the Endothelial NO-Synthase Gene Influences Human Blood Oxygen Transport

Background: Nitric oxide (NO) interacts with haemoglobin to help blood carry oxygen to tissues. The polymorphism G894 T of endothelial nitric oxide synthase (G894T eNOS) affects NO synthase activity and expression. Polymorphism's effects on oxygen-dependent biological processes are currently unknown.Methods: Study subjects were healthy young males aged 18 to 24 years (n = 172). Blood samples were drawn from the cubital vein at rest, 12 hours after the last food intake. G894T polymorphism and the blood oxygen indices (pO₂, CvO₂, SO₂, pH, p50 standard [temperature = 37 °C, pH = 7.4, pCO₂ = 40 mm Hg], and p50 actual [measured at actual temperature, pH, and pCO₂]) were determined. Results: In persons with the TT-genotype, the oxygen content in venous blood was 48.7% (p=0.006, q=0.016) lower compared to subjects with the GT-genotype and 49.4% (p=0.012, q=0.017) lower compared to subjects with the GG-genotype. The saturation of blood in carriers of the TT-genotype was 32.4% (p=0.014, q=0.018) and 35.9% (p=0.007, q=0.016) lower as opposed to subjects with the GT-genotype and the GG-genotype, respectively. In the blood of subjects with the TT-genotype, the oxygen tension was 26.1% (p=0.008, q=0.016) lower as compared to subjects with the GT-genotype and 27.4% (p=0.012, q=0.017) lower as opposed to the GG-genotype. Volunteers with a common allele in their genotype (GG + GT) had an oxygen tension approximately 36.5 % higher than subjects with the TT genotype, whereas subjects with the TT genotype exhibited oxygen tension about 26.7 % lower than those carrying a common allele (p = 0.008). The blood pH values of the subjects having the recessive genotype were 0.022 units lower compared to the GG (p=0.038, q=0.038) and GT (p=0.034, q=0.036) genotypes. In volunteers with the TT-genotype, the p50stand parameter was 5.8% (p=0.019, q=0.023) lower compared to subjects with the GT-genotype and 6.8% (p=0.009, q=0.016) lower compared to volunteers with the GG-genotype. In persons with two T-alleles in their genotype, p50act was 5.4% (p=0.008, q=0.016) lower compared to subjects with the GT-genotype and 6.4% (p=0.005, q=0.016) 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 the G894T polymorphism of the NOS3 gene contributes to the formation of the oxygen transport function of blood.Keywords: Blood Oxygen, Nitric oxide, polymorphism G894 T, Endothelium NOS, Genotype