Adverse remodeling of the obtuse marginal artery in compensatory hypertrophied myocardium from spontaneously hypertensive rats.

Abstract

BACKGROUND: Spontaneously hypertensive rats (SHR) serve as a model of genetic hypertension. Adverse remodeling of a coronary artery has been reported in SHR. This model is used to study new therapies in regression vascular remodeling. However, no data are available that show remodeling of the intramyocardial branch of the obtuse marginal artery in 10-month-old SHR. This study was designed to assess remodeling (changes in vascular structure and fibrosis) of this coronary artery. METHODS AND RESULTS: The study was performed on 10-month-old male SHR (n=7) and normotensive control Wistar Kyoto rats (WKY) (n=7). Using histology, we show that the external diameter, lumen diameter, wall width, and cross-sectional area of the intramyocardial artery were significantly greater in SHR than in WKY. The wall-to-lumen ratio was similar in SHR and WKY. The collagen volume density of the intramyocardial artery in SHR was significantly greater than in WKY. CONCLUSIONS: Our results show hypertrophic outward remodeling in the intramyocardial branch of the obtuse marginal artery of the left ventricle in SHR. This artery can serve as a new vascular bed from adult SHR to study novel therapies in regression coronary artery remodeling.