Incomplete Reverse Remodeling in Aged Mice Exposed to Pulmonary Hypertension-Induced Right Ventricular Failure

Right ventricle (RV) function is the strongest predictor of survival in pulmonary hypertension (PH) and age-related HF; however no therapies exist to improve RV function. Understanding mechanisms by which the RV undoes pathological remodeling (reverse remodeling) might aid in identifying therapies for this unmet need. Our objective was to determine whether the aged RV can undergo reverse remodeling following pathological afterload (PH). We hypothesized that return to normoxia after hypoxia-induced PH would result in attenuation of RV mass and improved RV function. We exposed male and female aged (~18 months) C57Bl6 mice to hypobaric hypoxia (HH) for 4 weeks before returning them to normoxia for 3 (WK3RR) or 6 (WK6RR) weeks. HH induced RV hypertrophy by RV myocyte area which was attenuated at Wk3RR and WK6RR in both male (Con: 425 μm2 ± 104, HH: 740 μm2 ± 125, WK3RR: 447 μm2 ± 129, WK6RR: 530 μm2 ± 187) and female mice (Con: 340 μm2 ± 116, HH: 770 μm2 ± 35, WK3RR: 516 μm2 ± 186, WK6RR: 655 μm2 ± 224). HH stimulated fibrosis by collagen deposition that was also reversed during normoxia re-exposure in male mice only (Con: 4.1% ± 1.0, HH: 10.8% ± 0.8, WK3RR: 4.2% ± 0.8, WK6RR: 2.5% ± 0.7). However, HH decreased RV systolic function by fractional area change (FAC) that was also not rescued by normoxia re-exposure. The aged RV can undergo morphological reverse remodeling in response to HH; however RV function does not improve with resolution of afterload. Further investigation into the mechanisms of reverse remodeling may identify potential drug therapies for maladaptive RV remodeling. AHA-Predoctoral Fellowship 897622 (BDM). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.