Novo dispositivo de medida de rigidez arterial - pOpmètri® e suas correlações com análises morfométricas e densidade de colágeno em artérias de ratos de diferentes idades

Abstract

Arterial stiffness measurement, evaluated by pulse wave velocity (PWV), is a predictor of cardiovascular events. Among the main factors that affect arterial stiffness are cross-sectional area, medial wall thickening, wall-to-lumen ratio and collagen density. Recently, a device using finger-toe pulse wave velocity was validated for humans study, but to better understand the mechanisms that change arterial stiffness, it is necessary to use the arterial vessel for genic, proteic and histological analysis. Therefore, a new device – popmètre® – was designed for measurements of PWV in animals and it was not validated yet. The aim of this study was to evaluate the validity, reliability and objectivity of a new device pOpmètri® 1.0 for animal studies. Forty-two Wistar rats were allocated into 3 groups of different ages: Young: 1 month; Adult: 4 months and Older: 12 months. Two photodiodes were positioned on the right thoracic and pelvic members for PWV measurement, on anesthetized rats. Then, aorta, carotid, femoral and renal arteries were extracted and prepared for morphometric and histological analysis (cross sectional area – CSA, wall thickness and collagen density). Results of PWV and vessel structure were then correlated using Pearson correlation test (p<0.05). As expected, PWV was 46% higher in adult rats compared with young rats and 20% higher in aged rats compared with adult ones. Cross sectional area was significantly higher in aged rats compared with young rats in aorta (+151%), carotid (+94%), femoral (+62%) and renal (251%) arteries. Wall thickness was not altered among groups. Also, collagen density was higher aged rats compared with young rats in (aorta: 276%; femoral: 290% and carotid: 234%). A significant correlation was observed between CSA and PWV in all arteries: aorta (r=0.5642; p<0.001); carotid (r=0.6854 p<0.001); femoral (r=0.6642 p<0.001) and renal (r=0.7817; p<0.0001). Wall thickness did not correlate with PWV. In addition, collagen density correlated with PWV in aorta (r=0,8854), femoral (r=0,9031) and carotid (r=0,9051). The results of this present study allow us to suggest that PWV measurement, obtained by a new device pOpmètri® for small animals, was able to detect age-related vessel structure in rats. The device was approved of tests of validity, reliability and objectivity.