Alamandine enhances cardiomyocyte contractility in hypertensive rats through a nitric oxide-dependent activation of CaMKII

Overstimulation of the renin-angiotensin system (RAS) has been implicated in the pathogenesis of various cardiovascular diseases. Alamandine is a peptide newly identified as a protective component of the RAS; however, the mechanisms involved in its beneficial effects remain elusive. By using a well-characterized rat model of hypertension, the TGR (mREN2)27, we show that mREN ventricular myocytes are prone to contractile enhancement mediated by short-term alamandine (100 nmol/L) stimulation of Mas-related G protein-coupled receptor member D (MrgD) receptors, while Sprague-Dawley control cells showed no effect. Additionally, alamandine prevents the Ca²⁺ dysregulation classically exhibited by freshly isolated mREN myocytes. Accordingly, alamandine treatment of mREN myocytes attenuated Ca²⁺ spark rate and enhanced Ca²⁺ reuptake to the sarcoplasmic reticulum. Along with these findings, KN-93 fully inhibited the alamandine-induced increase in Ca²⁺ transient magnitude and phospholamban (PLN) phosphorylation at Thr17, indicating CaMKII as a downstream effector of the MrgD signaling pathway. In mREN ventricular myocytes, alamandine treatment induced significant nitric oxide (NO) production. Importantly, NO synthase inhibition prevented the contractile actions of alamandine, including PLN-Thr17 phosphorylation at the CaMKII site, thereby indicating that NO acts upstream of CaMKII in the alamandine downstream signaling. Altogether, our results show that enhanced contractile responses mediated by alamandine in cardiomyocytes from hypertensive rats occur through a NO-dependent activation of CaMKII.

Expression of adhesion molecules in chronic B-cell lymphoproliferative disorders

BACKGROUND AND OBJECTIVE

Abnormalities in the expression of cell adhesion molecules (CAM) are thought to influence the patterns of intranodal growth and hematogeneous spread of malignant cells in chronic lymphoproliferative disorders (LPD). Therefore, the characterization of CAM phenotypic profiles of the neoplastic clones in LPD may help to identify distinct subtypes with prognostic implications. In this work we sought to investigate whether the expression of CAM by circulating malignant cells in patients with B-cell LPD differed from that of normal peripheral blood B-lymphocytes (PBL) and whether the observed phenotypic patterns could be correlated to other biological and clinical parameters of known clinical relevance.

DESIGN AND METHODS

Peripheral blood mononuclear cells were obtained from 148 patients with B-cell chronic lymphocytic leukemia (B-CLL), 52 with B-cell non-Hodgkin lymphomas (NHL) and 10 with hairy cell leukemia (HCL). The expression of CAM was analyzed by flow cytometry using monoclonal antibodies against CD49d, CD29, CD11a, CD11b, CD11c, CD18, CD62L, CD54 and CD44.

RESULTS

All CAM were detected in normal peripheral blood B-lymphocytes, except CD11c and CD54, which were present in only a minority of cells. Fluorescence mean channel values (FMC) showed that all molecules, with the exception of CD44, were expressed with dim intensity. Emerging patterns of CAM expression, as assessed by FMC values, were observed in different LPD: thus, B-CLL is characterized by a very low expression of CD49d/CD29 and beta 2 integrins. In this disorder, CD49d/CD29, CD11a, and CD54 increase with tumor burden; NHL show high expression of CD29 and CD54; strong expression of all molecules (except CD11a) was found in HCL, particularly CD11c (FMC values 60 times higher than normal). CD62L was faintly expressed in all diagnostic groups, whereas CD11c showed consistently high FMC values.

INTERPRETATION AND CONCLUSIONS

The data shows that the phenotypic characterization of LPD can be further refined by the analysis of their patterns of CAM expression which may help to identify distinct subsets within each nosological group.