left-atrial-stenosis-induced-pulmonary-venous-arterialization-group-2

Left Atrial Stenosis Induced Pulmonary Venous Arterialization and Group 2 Pulmonary Hypertension in Rat

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of ...

The Jikei University School of Medicine

Hepatic fibrosis progresses with right heart failure, and becomes cardiac cirrhosis in a severe case. Although its causal factor still remains unclear. Here we evaluated the progression of hepatic fibrosis using a pulmonary artery banding (PAB)-induced right heart failure model and investigated whether cardiac output (CO) is responsible for the progression of hepatic fibrosis.

Low Cardiac Output Leads Hepatic Fibrosis in Right Heart Failure Model Rats.

Interstitial myocardial fibrosis is one of the factors responsible for dysfunction of the heart. However, how interstitial fibrosis affects cardiac function and excitation-contraction coupling (E-C coupling) has not yet been clarified. We developed an animal model of right ventricular (RV) hypertrophy with fibrosis by pulmonary artery (PA) banding in rats. Two, four, and six weeks after the PA-banding operation, the tension and intracellular Ca2+ concentration of RV papillary muscles were simultaneously measured (n = 33). The PA-banding rats were clearly divided into two groups by the presence or absence of apparent interstitial fibrosis in the papillary muscles: F+ or F- group, respectively. The papillary muscle diameter and size of myocytes were almost identical between F+ and F-, although the RV free wall weight was heavier in F+ than in F-. F+ papillary muscles exhibited higher stiffness, lower active tension, and lower Ca2+ responsiveness compared with Sham and F- papillary muscles. In addition, we found that the time to peak Ca2+ had the highest correlation coefficient to percent of fibrosis among other parameters, such as RV weight and active tension of papillary muscles. The phosphorylation level of troponin I in F+ was significantly higher than that in Sham and F-, which supports the idea of lower Ca2+ responsiveness in F+. We also found that connexin 43 in F+ was sparse and disorganized in the intercalated disk area where interstitial fibrosis strongly developed. In the present study, the RV papillary muscles obtained from the PA-banding rats enabled us to directly investigate the relationship between fibrosis and cardiac dysfunction, the impairment of E-C coupling in particular. Our results suggest that interstitial fibrosis worsens cardiac function due to 1) the decrease in Ca2+ responsiveness and 2) the asynchronous activation of each cardiac myocyte in the fibrotic preparation due to sparse cell-to-cell communication.

Impairment of Excitation-Contraction Coupling in Right Ventricular Hypertrophied Muscle with Fibrosis Induced by Pulmonary Artery Banding.

A rat model of left atrial stenosis-associated pulmonary hypertension due to left heart diseases was prepared to elucidate its mechanism.

Article	Year
Low Cardiac Output Leads Hepatic Fibrosis in Right Heart Failure Model Rats. PloS one\| PubMed ID: 26863419	2016
Impairment of Excitation-Contraction Coupling in Right Ventricular Hypertrophied Muscle with Fibrosis Induced by Pulmonary Artery Banding. PloS one\| PubMed ID: 28068381	2017
Pulmonary hypertension due to left heart disease causes intrapulmonary venous arterialization in rats. The Journal of thoracic and cardiovascular surgery\| PubMed ID: 28755882	2017
Elusive mechanisms responsible for pulmonary hypertension. The Journal of thoracic and cardiovascular surgery\| PubMed ID: 29245199	2018

Yoshitaka Fujimoto

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