Differences in the microcirculation disturbance in the right and left ventricles of neonatal rats with hypoxic pulmonary hypertension

Abstract

Microcirculation disturbance is a crucial pathological basis of heart damage; however, microcirculation alterations induced by hypoxic pulmonary hypertension (HPH) remain unknown, and the left ventricle (LV) in HPH is conventionally ignored. Herein, we investigated the changes in the cardiac structure, function and microcirculation after HPH and further compared the differences between the right ventricle (RV) and LV. Using a neonatal rat model of HPH, we found RV myocardial hypertrophy, dysfunction and poor myocardial perfusion in HPH rats. Additionally, RV microcirculation disturbance manifested as the abnormal expression of endothelin-1/eNOS and increased expression of intercellular cell adhesion molecule-1 (ICAM-1) or E-selectin 3 days after hypoxia, followed by vascular inflammation, coronary arterial remodeling and microvascular sparseness. Impairment in LV vasodilation was detected in rats after 3 days of hypoxia; however, no obvious microvascular rarefaction or inflammatory reaction was observed in the LV. In conclusion, our results suggest that HPH mainly triggers RV microcirculation disturbances, causing low myocardial perfusion damage and cardiac dysfunction. Despite the differences in the RV and LV, their impaired microvascular function, mediated by endothelial cells, occurs almost simultaneously after HPH, earlier than cardiac functional or structural abnormalities.

Keywords: Biventricular differences; Cardiac damage; Hypoxic pulmonary hypertension; Myocardial microcirculation; Newborn rats.