[Change and significance in the levels of plasma urotensin II and catestatin in children with postural orthostatic tachycardia syndrome].

OBJECTIVE: To explore possible mechanisms by analyzing cardiovascular bioactive peptides levels in children with postural orthostatic tachycardia syndrome (POTS). METHODS: Forty-six children diagnosed as POTS (POTS group, aged 12.1±2.8 years) and 20 healthy children (control group, aged 11.5±3.6 years) were enrolled as controls in this clinical controlled study. Two kinds of cardiovascular bioactive peptides named urotensin II (UII) and catestatin (Cs) were measured by using enzyme immunoassay. The comparisons between the two groups were made by independent t test or non-parametric test. Correlation analyses between plasma levels of bioactive peptides and changes in heart rate during standing test or head-up tilt test (HUT) were conducted using bivariate correlations. RESULTS: The plasma UII levels were significantly lower in POTS group as compared with those of controls [0.41 (0.27, 0.85) μg/L in POTS group vs. 0.46 (0.35, 1.41) μg/L in control group, P<0.05]. The plasma UII level was negatively correlated with the increase in heart rate during standing test or head-up tilt test (correlation coefficient-0.363, P<0.05). No difference was found in plasma Cs levels between the two groups [ 0.48 (0.20, 1.91) μg/L in POTS group vs. 0.48 (0.20, 1.91) μg/L in control group, P>0.05]. CONCLUSION: POTS children had low levels of plasma UII, and disturbance of vascular tone regulation might play a role in POTS of children.