Abstract
Recent evidence demonstrates that masked hypertension (MH) is a significant predictor of cardiovascular disease, while apelin and relaxin are two novel factors with a significant role in vascular regulation. Apelin is an adipokine that elicits endothelium-dependent vasorelaxation and reduces arterial blood pressure, while relaxin is a protein hormone that induces the production of nitric oxide and vascular endothelial growth factor and inhibits endothelin and angiotensin II. This study aimed to investigate whether apelin and relaxin plasma levels are affected in patients with MH and compare the findings with those of healthy normotensives. One hundred-thirty (60 men, 70 women) healthy patients with a mean age of 45±12 years who had clinic blood pressure <140/90 mmHg were studied. The whole study population underwent 24-hour ambulatory blood pressure monitoring (ABPM). According to the ABPM recordings, 24 individuals (8 men, 16 women) had MH and the remaining 106 patients (52 men, 54 women) had normal ABPM recordings. Apelin and relaxin plasma levels were determined in both groups (enzyme-linked immunosorbent assay method). The apelin (220±121 vs 315±147 pg/mL, P=.001) and relaxin (35.2±6.7 vs 56.8±13.6 pg/mL, P<.001) plasma levels were significantly lower in the masked hypertensive group compared with normotensive controls. Our findings suggest that patients with masked hypertension have significantly lower apelin and relaxin levels. This observation may have prognostic significance for future cardiovascular events in patients with MH and needs further investigation.