Association between HMOX-1 genotype and cardiac function during exercise

Abstract

The human gene for heme oxygenase-1 (HMOX-1) plays an important role in the regulation of cardiovascular function and its adaptive response to a variety of stressors. The purpose of this study was to examine the possible association between HMOX-1 genotypes (for –1135A/G, –413A/T, and rs5755720 polymorphisms) and cardiac structural and functional parameters at rest and during submaximal cycle-ergometer exercise (50, 100, and 150 W) in a pre-training state (baseline) and after endurance training (18 weeks, 95%~105% individual ventilatory threshold). The study population consisted of 102 Chinese young males (non-athletes) of Han origin. For the –1135A/G polymorphism, we found a significant genotype effect (p < 0.05) in cardiac output (Q) corrected for body surface area (BSA; Q·BSA–1) at 50 W and stroke volume (SV) corrected for BSA (SV·BSA–1) at 100 W. For the –413A/T polymorphism, we found a significant genotype effect (p < 0.05) in ejection fraction (EF) at 100 W. For the rs5755720 polymorphism, we found a significant genotype effect (p < 0.01 or p < 0.05) in most variables (Q·BSA–1 across all workloads, SV·BSA–1 at 100 W, and EF at 50 and 100 W). Briefly, rs5755720 individuals with a CC genotype presented overall higher values in the different cardiac variables than their CT and (or) TT counterparts. In summary, although more research is needed with diseased populations and other ethnic groups, we found preliminary evidence of an association between cardiac response to submaximal exercise and HMOX-1 genotype. The present preliminary findings could provide insights to future studies searching for cardioprotective genotypes.