Sexual dimorphism in right ventricular adaptation to pressure overload involves differential angiogenic response.

This study investigated the sexual dimorphism in right ventricle (RV) remodeling in right heart failure susceptible Fischer CDF rats using the pulmonary artery banding (PAB) model. Echocardiography and hemodynamic measurements were performed in adult male and female Fischer CDF rats at 1- or 2-weeks post-PAB. RV systolic pressure and RV hypertrophy were significantly elevated in PAB rats compared to sham control at 1- and 2-weeks post-PAB; however, no differences were observed between male and female rats. Increase in cardiomyocyte cross-sectional area and RV end-diastolic diameter was observed in male rats compared to female rats at 2-weeks post-PAB. Conversely, higher fractional area change and cardiac index were observed in female rats compared to male rats at 2-weeks post-PAB. To explore the mechanisms, a focused PCR array was performed and higher expression of angiogenic genes, including sphingosine kinase-1 (Sphk1), was observed in the RV of female rats compared to male rats. Consistent with the higher angiogenic gene expression, female rats had a higher RV vascular density at 2-weeks post-PAB compared to male rats. Female RV endothelial cells (RVEC) had better angiogenic ability compared to male cells that was potentiated by estradiol. Furthermore, effect of estradiol on RVEC was inhibited by Sphk1 inhibitor (PF-543). Together, female Fischer CDF rats develop adaptive RV remodeling post-PAB compared to mal-adaptive remodeling in male rats. Moreover, the adaptive remodeling in female rats is associated with better RV angiogenic response that may result from better angiogenic ability of female RVEC and proangiogenic effects of estradiol through Sphk1.