Reduction of left ventricular hypertrophy: how beneficial?

Effect of SKF‑96365 on cardiomyocyte hypertrophy induced by angiotensin II

Angiotensin II (Ang II) is an important bioactive peptide in the renin-angiotensin system, and it can contribute to cell proliferation and cardiac hypertrophy. Dysfunctions in transient receptor potential canonical (TRPC) channels are involved in many types of cardiovascular diseases. The aim of the present study was to investigate the role of the TRPC channel inhibitor SKF-96365 in cardiomyocyte hypertrophy induced by Ang II and the potential mechanisms of SKF-96365. H9c2 cells were treated with different concentrations of Ang II. The expression levels of cardiomyocyte hypertrophy markers and TRPC channel-related proteins were also determined. The morphology and surface area of the H9c2 cells, the expression of hypertrophic markers and TRPC channel-related proteins and the [³H] leucine incorporation rate were detected in the Ang II-treated H9c2 cells following treatment with the TRPC channel inhibitor SKF-96365. The intracellular Ca²⁺ concentration was tested by flow cytometry. The present results suggested that the surface area of H9c2 cells treated with Ang II was significantly increased compared with untreated H9c2 cells. The fluorescence intensity of α-actinin, the expression of hypertrophic markers and TRPC-related proteins, the [³H] leucine incorporation rate and the intracellular Ca²⁺ concentration were all markedly increased in the Ang II-treated H9c2 cells but decreased following SKF-96365 treatment. The present results suggested that Ang II induced cardiomyocyte hypertrophy in H9c2 cells and that the TRPC pathway may be involved in this process. Therefore, SKF-96365 can inhibit cardiomyocyte hypertrophy induced by Ang II by suppressing the TRPC pathway. The present results indicated that TRPC may be a therapeutic target for the development of novel drugs to treat cardiac hypertrophy.

Carvedilol in hypertension treatment

Although β-blockers have been previously shown to effectively reduce blood pressure (BP) and have been used for hypertension treatment for over 40 years, their effect on cardiovascular morbidity and mortality in hypertensive patients remains controversial and its use in uncomplicated hypertension is currently under debate. However, data on the above field derive mainly from studies which were conducted with older agents, such as atenolol and metoprolol, while considerable pharamacokinetic and pharmacodynamic heterogeneity is present within the class of β-blockers. Carvedilol, a vasodilating non-cardioselective β-blocker, is a compound that seems to give the opportunity to the clinician to use a cardioprotective agent without the concerning hemodynamic and metabolic actions of traditional β-blocker therapy. In contrast with conventional β-blockers, carvedilol maintains cardiac output, has a less extended effect on heart rate and reduces BP by decreasing vascular resistance. Further, several studies has shown that carvedilol has a beneficial or at least neutral effect on metabolic parameters, such as glycemic control, insulin sensitivity, and lipid metabolism, suggesting that they could be used in subjects with the metabolic syndrome or diabetes without negative consequences. This article summarizes the distinct pharmacologic, hemodynamic, and metabolic properties of carvedilol in relation to conventional β-blockers, attempting to examine the potential use of this agent for hypertension treatment.

Cardiac dysfunction and heart failure are associated with abnormalities in the subcellular distribution and amounts of oligomeric muscle LIM protein

Prolonged hemodynamic overload results in cardiac hypertrophy and failure with detrimental changes in myocardial gene expression and morphology. Cysteine-rich protein 3 or muscle LIM protein (MLP) is thought to be a mechanosensor in cardiac myocytes. Therefore, the subcellular location of MLP may have functional implications in health and disease. Our hypothesis is that MLP becomes mislocalized after prolonged overload, resulting in impaired mechanosensing in cardiac myocytes. Using the techniques of biochemical subcellular fractionation and immunocytochemistry, we found MLP exhibits oligomerization in the membrane and cytoskeleton of cultured cardiac rat neonatal myocytes. Nuclear MLP was always monomeric. MLP translocated to the nucleolus in response to 10% cyclic stretch at 1 Hz for 48 h. This was associated with a threefold increase in S6 ribosomal protein ( P < 0.01; n = 3 cultures). Adenoviral overexpression of MLP also resulted in a twofold increase in S6 protein, suggesting that MLP can activate ribosomal protein synthesis in the nucleolus. In ventricles from aortic-banded and myocardially infarcted rat hearts, nuclear MLP increased by twofold ( P < 0.01; n = 7) along with a significant decrease in the nonnuclear oligomeric fraction. The ratio of nuclear to nonnuclear MLP increased threefold in both groups ( P < 0.01; n = 7). In failing human hearts, there was almost a complete loss of oligomeric MLP. Using a flag-tagged adenoviral MLP, we demonstrate that the COOH terminus is required for oligomerization and that this is a precursor to stretch sensing and subsequent nuclear translocation. Therefore, reduced oligomeric MLP in the costamere and cytoskeleton may contribute to impaired mechanosensing in heart failure.

Fosinopril reduces left ventricular mass in untreated hypertensive patients: a controlled trial

AIMS

Left ventricular hypertrophy is a powerful predictor of cardiovascular morbidity and mortality. We tested the hypothesis that fosinopril, an angiotensin-converting enzyme inhibitor, reduces left ventricular mass in hypertensive patients.

METHODS

Thirty-three patients with untreated mild essential hypertension were randomised to treatment with oral fosinopril (10 mg-20 mg daily) or placebo for 12 weeks. The primary outcome measure was the change in left ventricular mass index determined by echocardiography.

RESULTS

Diastolic blood pressure changed from 95.5+/-2.1 mmHg at baseline to 96.6+/-2.8 mmHg at the final visit in control patients and changed from 96.6+/-2.3 mmHg to 91.5+/-3.0 mmHg in patients treated with fosinopril (P= 0.04). Systolic blood pressure changed from 147.4+/-3.2 mmHg at baseline to 152.7+/-4.4 mmHg at the final visit in control patients and changed from 157.6+/-5.1 mmHg to 149.1+/-6.1 mmHg in patients treated with fosinopril (P=0.02). Fosinopril reduced diastolic pressure by 6.3 (95%CI 0.3-12.4) mmHg and systolic pressure by 13.3 (95%CI 2.7-23.8) mmHg compared with placebo. The left ventricular mass index changed from 110.0+/-8.3 gm(-2) to 113.1+/-8.7 g m(-2) in the control patients and changed from 120.8+/-5.8 g m(-2) to 109.0+/-7.5 g m(-2) in patients treated with fosinopril (P=0.02). Fosinopril reduced left ventricular mass index by 14.9 (95%CI 2.2-27.6) g m(-2) compared with placebo. There was no significant change in the left ventricular systolic or diastolic function, nor were there any significant changes in plasma electrolytes and renal function.

CONCLUSIONS

Treatment with fosinopril for 12 weeks reduced left ventricular mass significantly in hypertensive patients.