Stage­dependent changes of ß2­adrenergic receptor signaling in right ventricular remodeling in monocrotaline­induced pulmonary arterial hypertension.

Right ventricular (RV) remodeling coupled with extensive apoptosis in response to unrestrained biomechanical stress may lead to RV failure (RVF), which is the immediate cause of death in the majority of patients with pulmonary arterial hypertension (PAH). Overexpression of ß2­adrenergic receptor (ß2­AR) signaling has been reported to induce myocardiotoxicity in patients with left heart failure. However, the role of ß2­AR signaling in the pathophysiology of PAH development has remained elusive. To address this issue, the present study investigated the changes in cardiopulmonary function and structure, as well as the expression of regulators of fibrosis and apoptosis in RVF following monocrotaline (MCT; 60 mg/kg, i.p.)­induced PAH in rats. Cardiopulmonary function and structure, remodeling and apoptosis, as well as G protein­coupled receptor (GPCR) and ß2­AR signaling, were documented over a period of 6 weeks. In the early stages, elevated pulmonary arterial pressure, pulmonary lesions, RV hypertrophy, evidence of left ventricular (LV) hyperfunction and accelerated heart rate were observed in animals with MCT­induced PAH. The levels of angiotensin II receptor type 1b (Agtr1b), Agtr2 and Agt were markedly upregulated and the expression of ß2­AR phospho­Ser(355,356) steadily decreased in the right heart. As the disease progressed, LV dysfunction was observed, as evidenced by decreased LV systolic pressure and increased LV end­diastolic pressure, which was accompanied by a sustained increase in circulating brain natriuretic peptide levels. Of note, increased levels of cardiomyocyte apoptosis and concomitant RV remodeling, including hypertrophy, dilatation, inflammation and fibrosis, were observed, despite the enhanced RV contractility. Furthermore, alterations in GPCR signaling and activation in ß2­AR­Gs­protein kinase A/Ca2+/calmodulin­dependent kinase II signaling were observed in the late stages of PAH. These results suggested that treatment with MCT results in adaptive and maladaptive RV remodeling and apoptosis during the progression of PAH, which is accompanied by distinct changes in the ß2­AR signaling. Therefore, these results enable researchers to better understand of pathophysiology of MCT­induced PAH, as well as to determine the effects of novel therapies.

cAMP-PKA-CaMKII signaling pathway is involved in aggravated cardiotoxicity during Fuzi and Beimu Combination Treatment of Experimental Pulmonary Hypertension.

Aconiti Lateralis Radix Praeparata (Fuzi) and Fritillariae Thunbergii bulbus (Beimu) have been widely used clinically to treat cardiopulmonary related diseases in China. However, according to the classic rules of traditional Chinese medicine, Fuzi and Beimu should be prohibited to use as a combination for their incompatibility. Therefore, it is critical to elucidate the paradox on the use of Fuzi and Beimu combination therapy. Monocrotaline-induced pulmonary hypertension rats were treated with either Fuzi, Beimu, or their combination at different stages of PH. We demonstrated that at the early stage of PH, Fuzi and Beimu combination significantly improved lung function and reduced pulmonary histopathology. However, as the disease progressed, when Fuzi and Beimu combination were used at the late stage of PH, right ventricular chamber dilation was histologically apparent and myocardial apoptosis was significantly increased compared with each drug alone. Western-blotting results indicated that the main chemical ingredient of Beimu could down-regulate the protein phosphorylation levels of Akt and PDE4D, whereas the combination of Fuzi and Beimu could up-regulate PKA and CaMKII signaling pathways. Therefore, we concluded that Fuzi and Beimu combination potentially aggravated the heart injury due to the inhibition of PDK1/Akt/PDE4D axis and subsequent synergistic activation of ßAR-Gs-PKA/CaMKII signaling pathway.

The mechanism study in the interactions of sorghum procyanidins trimer with porcine pancreatic α-amylase.

To examine the mechanisms in the interaction of sorghum procyanidins trimer (SPT) with porcine pancreatic α-amylase (PPA), fluorescence quenching, circular dichroism, and UV spectra methods were adopted. The procyanidins binding mode, binding constant and effect of procyanidins on protein stability and conformation were determined. The fluorescence spectroscopy results showed that the Stern-Volmer quenching constant K(SV) of SPT on PPA, bimolecular quenching constant k(q), and apparent static quenching constant K were 2639.5 M(-1), 2.6395 × 10(11) M(-1) s(-1), and 495.19 M(-1), respectively. In addition, binding constant KA and number of binding sites were 872.971 M(-1) and 1, respectively. Circular dichroism study revealed that PPA conformation was altered by SPT with a major reduction of ß-sheet, increase of ß-turn, minor change of random coil. UV spectra indicated that SPT influenced the micro-environment of aromatic amino acid residues in PPA. These findings directly elucidate the mechanisms of high molecular weight SPT in interaction with PPA.