associations of uncoupling protein 2 ala55val and uncoupling protein 3-55c/t polymorphisms with heart rate variability in young oarsmen-a pilot study

Background: human heredity is known to determine about 50% of heart rate variability (hrv) based on a twin study; however, genetic polymorphisms causing increased hrv in athletes are not known. objectives: this article is aimed at studying the associations of uncoupling protein 2 (ucp2) ala55val (rs660339) and ucp3-55c/t (rs1800849) polymorphisms with heart rate variability (hrv) in trained oarsmen. methods: hrvindices (standard deviations of nnintervals (sdnn), rootmeansquare of successive differences (rmssd), hf, lf, vlf), stroke index and cardiac index of the young oarsmen (age 17.6±1.6 years old, n = 23) were determined by impedance cardiography method in the supine and standing positions. themaximumoxygen consumption (vo2max) was examined with a rower ergometer by means of a gas analyzer. polymorphisms of the ucp2 ala55val and the ucp3-55t/c were genotyped by polymerase chain reaction (pcr) method and length analysis of restriction products. results: it was found that both polymorphisms were not associated with vo2max. the ucp2 val/val genotype compared to the combined variant (ala/ala + ala/val) containing the 55 ala allele, as well as the ucp3 t/t genotype compared to the combined variant (c/t + c/c) containing the -55c allele were associated with low hr and increased hrv: sdnn, rmssd and hf vagal indices in the supine position. moreover, the athletes with the ucp3-55t/t genotype had a pronounced increase in heart rate (anova, p < 0.001) and a decrease in stroke index (anova, p = 0.005) in response to active orthostasis compared to c/t and c/c genotypes. conclusions: the ucp2 val/val and the ucp3 t/t genotypes may be genetic markers of increased hrv in the highly trained athletes, suggesting an influence of these ucp2/ucp3 polymorphisms on autonomic cardiovascular regulation.