Involvement of pentraxin-3 in the development of hypertension but not left ventricular hypertrophy in male spontaneously hypertensive rats

Abstract

Hypertension drives the development of concentric left ventricular hypertrophy (LVH). However, the relative contribution of pentraxin-3 (PTX-3), a novel marker for inflammatory cardiovascular disease, in the hypertrophic response to pressure overload has not been adequately elucidated. We investigated the role of PTX-3 in the development of LVH in spontaneously hypertensive rats (SHR), untreated and treated with either captopril (an ACE inhibitor) or hydralazine (a non-specific vasodilator). Three-month-old SHR received either 20 mg/kg/day hydralazine (SHR + H, n = 6), 40 mg/kg/day captopril (SHR + C, n = 6), or plain gelatine cubes (untreated SHR, n = 7) orally for 4 months. Wistar Kyoto rats (WKY, n = 7) were used as the normotensive controls. Blood pressure (BP) was measured using the tail-cuff method. Cardiac geometry and function were determined using M-mode echocardiography. Circulating concentrations of inflammatory markers were measured in plasma by ELISA. LV fibrosis and cardiomyocyte width were assessed by histology. Relative mRNA expression of PTX-3 was determined in the LV by RT-PCR. Untreated SHR exhibited greater systolic BP and relative wall thickness (RWT) compared to WKY. Captopril and hydralazine normalized BP but only captopril reversed RWT in SHR. Circulating PTX-3 and VCAM-1 levels were elevated in untreated SHR and reduced with captopril and hydralazine. Circulating PTX-3 was positively associated with systolic BP but lacked independent relations with indices of LVH. LV relative mRNA expression of PTX-3 was similar between the groups. PTX-3 may not be involved in the development of LVH in SHR, but plausibly reflects the localized inflammatory milieu associated with hypertension.