Metoprolol restores expression and vasodilatation function of AT2R in spontaneously hypertensive rats

Angiotensin-(1-9) in hypertension

Angiotensin-(1-9) [Ang-(1-9)] is a peptide of the non-canonical renin-angiotensin system (RAS) synthesized from angiotensin I by the monopeptidase angiotensin-converting enzyme type 2 (ACE2). Using osmotic minipumps, infusion of Ang-(1-9) consistently reduces blood pressure in several rat hypertension models. In these animals, hypertension-induced end-organ damage is also decreased. Several pieces of evidence suggest that Ang-(1-9) is the endogenous ligand that binds and activates the type-2 angiotensin II receptor (AT2R). Activation of AT2R triggers different tissue-specific signaling pathways. This phenomenon could be explained by the ability of AT2R to form different heterodimers with other G protein-coupled receptors. Because of the antihypertensive and protective effects of AT2R activation by Ang-(1-9), associated with a short half-life of RAS peptides, several synthetic AT2R agonists have been synthesized and assayed. Some of them, particularly CGP42112, C21 and novokinin, have demonstrated antihypertensive properties. Only two synthetic AT2R agonists, C21 and LP2-3, have been tested in clinical trials, but none of them like an antihypertensive. Therefore, Ang-(1-9) is a promising antihypertensive drug that reduces hypertension-induced end-organ damage. However, further research is required to translate this finding successfully to the clinic.

Regulator of G protein signalling 14 attenuates cardiac remodelling through the MEK-ERK1/2 signalling pathway

In the past 10 years, several publications have highlighted the role of the regulator of G protein signalling (RGS) family in multiple diseases, including cardiovascular diseases. As one of the multifunctional family members, RGS14 is involved in various biological processes, such as synaptic plasticity, cell division, and phagocytosis. However, the role of RGS14 in cardiovascular diseases remains unclear. In the present study, we used a genetic approach to examine the role of RGS14 in pathological cardiac remodelling in vivo and in vitro. We observed that RGS14 was down-regulated in human failing hearts, murine hypertrophic hearts, and isolated hypertrophic cardiomyocytes. Moreover, the extent of aortic banding-induced cardiac hypertrophy and fibrosis was exacerbated in RGS14 knockout mice, whereas RGS14 transgenic mice exhibited a significantly alleviated response to pressure overload. Furthermore, research of the underlying mechanism revealed that the RGS14-dependent rescue of cardiac remodelling was attributed to the abrogation of mitogen-activated protein kinase (MEK)–extracellular signal-regulated protein kinase (ERK) 1/2 signalling. The results showed that constitutive activation of MEK1 nullified the cardiac protection in RGS14 transgenic mice, and inhibition of MEK–ERK1/2 by U0126 reversed RGS14 deletion-related hypertrophic aggravation. These results demonstrated that RGS14 attenuated the development of cardiac remodelling through MEK–ERK1/2 signalling. RGS14 exhibited great potential as a target for the treatment of pathological cardiac remodelling.

A randomized, double blind, placebo-controlled, multicenter phase II trial of Allisartan Isoproxil in essential hypertensive population at low-medium risk

BACKGROUND

Angiotensin II receptor blockers (ARBs) is a well-tolerated class of antihypertensive agents, exhibiting effective antihypertensive and cardiovascular protective function. The objective of the study was to examine the efficacy and safety of Allisartan Isoproxil, a newly developed, selective, nonpeptide blocker of the angiotensin II type 1 receptor (AT1R), in essential hypertensive patients at low-medium risk.

METHODS AND FINDINGS

A Phase II prospective, randomized, double-blind, placebo-controlled, multicenter trial comparing Allisartan Isoproxil 240mg versus placebo was conducted in essential hypertensive patients at low-medium risk at 8 sites in China. After a 2-week placebo baseline period, 275 patients received once-daily treatment with Allisartan Isoproxil 240mg or placebo randomly for 8 weeks. Systolic/diastolic blood pressure (SBP/DBP) was measured at week 2, 4 and 8. By the end of treatment, mean reductions from baseline of SBP and DBP in Allisartan Isoproxil and placebo groups were 14.5/10.4 and 8.3/7.7 mmHg, respectively (P<0.01). The rate of effective blood pressure control in Allisartan Isoproxil group was significantly higher than in placebo group at week 4 (61.3% vs 50.0%, P<0.05) and week 8 (67.2% vs 48.6%, P<0.01). In terms of safety and tolerability, there were no report of death and serious adverse event (SAE) in all subjects. There was no difference of frequency between two groups in adverse event (AE) and adverse drug reaction (ADR) (P>0.05). No one withdraw because of an ADR in two groups. 124 patients received additional 56 weeks treatment with Allisartan Isoproxil and 84 of them completed the study. The rate of effective BP control kept up to 80% since week 24. No significant clinical change was observed and ADRs were generally mild or moderate during the long-term study.

CONCLUSIONS/SIGNIFICANCE

Allisartan Isoproxil 240mg was effective and safe for essential hypertension patients at low-medium risk.

TRIAL REGISTRATION

http://www.chictr.org/cn/ ChiCTR-TRC-10000886.