The effect of indapamide on development of myocardial hypertrophy and fibrosis in L-NAME-induced hypertension in rat

Chronic aerobic exercise associated to low-dose L-NAME improves contractility without changing calcium handling in rat cardiomyocytes

Nitric oxide (NO) inhibition by high-dose NG-nitro-L-arginine methyl ester (L-NAME) is associated with several detrimental effects on the cardiovascular system. However, low-dose L-NAME increases NO synthesis, which in turn induces physiological cardiovascular benefits, probably by activating a protective negative feedback mechanism. Aerobic exercise, likewise, improves several cardiovascular functions in healthy hearts, but its effects are not known when chronically associated with low-dose L-NAME. Thus, we tested whether the association between low-dose L-NAME administration and chronic aerobic exercise promotes beneficial effects to the cardiovascular system, evaluating the cardiac remodeling process. Male Wistar rats were randomly assigned to control (C), L-NAME (L), chronic aerobic exercise (Ex), and chronic aerobic exercise associated to L-NAME (ExL). Aerobic training was performed with progressive intensity for 12 weeks; L-NAME (1.5 mg·kg^-1·day^-1) was administered by orogastric gavage. Low-dose L-NAME alone did not change systolic blood pressure (SBP), but ExL significantly increased SBP at week 8 with normalization after 12 weeks. Furthermore, ExL promoted the elevation of left ventricle (LV) end-diastolic pressure without the presence of cardiac hypertrophy and fibrosis. Time to 50% shortening and relaxation were reduced in ExL, suggesting a cardiomyocyte contractile improvement. In addition, the time to 50% Ca²⁺ peak was increased without alterations in Ca²⁺ amplitude and time to 50% Ca²⁺ decay. In conclusion, the association of chronic aerobic exercise and low-dose L-NAME prevented cardiac pathological remodeling and induced cardiomyocyte contractile function improvement; however, it did not alter myocyte affinity and sensitivity to intracellular Ca²⁺ handling.

Mechanisms of cardiac collagen deposition in experimental models and human disease

The inappropriate deposition of extracellular matrix within the heart (termed cardiac fibrosis) is associated with nearly all types of heart disease, including ischemic, hypertensive, diabetic, and valvular. This alteration in the composition of the myocardium can physically limit cardiomyocyte contractility and relaxation, impede electrical conductivity, and hamper regional nutrient diffusion. Fibrosis can be grossly divided into 2 types, namely reparative (where collagen deposition replaces damaged myocardium) and reactive (where typically diffuse collagen deposition occurs without myocardial damage). Despite the widespread association of fibrosis with heart disease and general understanding of its negative impact on heart physiology, it is still not clear when collagen deposition becomes pathologic and translates into disease symptoms. In this review, we have summarized the current knowledge of cardiac fibrosis in human patients and experimental animal models, discussing the mechanisms that have been deduced from the latter in relation to the former. Because assessment of the extent of fibrosis is paramount both as a research tool to further understanding and as a clinical tool to assess patients, we have also summarized the current state of noninvasive/minimally invasive detection systems for cardiac fibrosis. Albeit not exhaustive, our aim is to provide an overview of the current understanding of cardiac fibrosis, both clinically and experimentally.

Effect of QiShenYiQi Pill on Myocardial Collagen Metabolism in Rats with Partial Abdominal Aortic Coarctation

This study investigated the effect of QiShenYiQi pill (QSYQ) on myocardial collagen metabolism in rats with partial abdominal aortic coarctation and explored its mechanism of action. A series of assays were used to detect the effect and mechanism of QSYQ on systolic blood pressure, heart mass index, left ventricle mass index, HYP, expression of PICP, PIIINT, and CTX-I in serum, MMP-1, and TIMP-1 expression in myocardium. We observed that QSYQ can reduce the rate of myocardial collagen synthesis and increase the rate of myocardial collagen degradation. It also effectively improved the degree of myocardial fibrosis in partial abdominal aortic rats and it had a tendency to have a greater effect with longer treatment duration, which is related to the mechanism of regulation of MMP-1 and TIMP-1 expression in the myocardial rat.

The effect of indapamide versus hydrochlorothiazide on ventricular and arterial function in patients with hypertension and diabetes: results of a randomized trial

OBJECTIVE

The objective of this study is to compare the effects of 2 types of diuretics, indapamide and hydrochlorothiazide, added to an angiotensin-converting enzyme inhibitor, on ventricular and arterial functions in patients with hypertension and diabetes.

METHODS

This is a prospective, randomized, active-controlled, PROBE design study in 56 patients (57 ± 9 years, 52% men) with mild-to-moderate hypertension and type 2 diabetes, with normal ejection fraction, randomized to either indapamide (1.5 mg Slow Release (SR)/day) or hydrochlorothiazide (25 mg/d), added to quinapril (10-40 mg/d). All patients had conventional, tissue Doppler and speckle tracking echocardiography and assessment of endothelial and arterial functions and biomarkers, at baseline and after 6 months.

RESULTS

Baseline characteristics were similar between groups; systolic and diastolic blood pressures decreased similarly, by 15% and 9% on indapamide and by 17% and 10% on hydrochlorothiazide (P < .05). Mean longitudinal systolic velocity and longitudinal strain increased by 7% and 14% on indapamide (from 5.6 ± 1.8 to 6.0 ± 1.1 cm/s and from 16.2% ± 1.8% to 18.5% ± 1.1%, both P < .05), but did not change on hydrochlorothiazide (P < .05 for intergroup differences), whereas ejection fraction and radial systolic function did not change. Similarly, mean longitudinal early diastolic velocity increased by 31% on indapamide (P < .05), but did not change on hydrochlorothiazide (P < .05 for intergroup differences). These changes were associated with improved endothelial and arterial functions on indapamide, but not on hydrochlorothiazide.

CONCLUSION

Indapamide was found to improve measures of endothelial and arterial functions and to increase longitudinal left ventricular function compared with hydrochlorothiazide in patients with hypertension and diabetes, after 6 months of treatment. This study suggests that indapamide, a thiazide-like diuretic, has important vascular effects that can improve ventriculoarterial coupling.

Which thiazide to choose as add-on therapy for hypertension?

Combined therapy is required in the majority of patients with hypertension to achieve blood pressure (BP) targets. Although different antihypertensive drugs can be combined, not all combinations are equally effective and safe. In this context, the combination of a renin angiotensin system inhibitor with a diuretic, usually a thiazide, particularly hydrochlorothiazide (HCTZ) or thiazide-like diuretics, such as chlorthalidone or indapamide, is recommended. However, not all diuretics are equal. Although HCTZ, chlorthalidone, and indapamide as add-on therapy effectively reduce BP levels, the majority of studies have obtained greater BP reductions with chlorthalidone or indapamide than with HCTZ. Moreover, there are data showing benefits with chlorthalidone or indapamide beyond BP. Thus, chlorthalidone seems to have pleiotropic effects beyond BP reduction. Moreover, compared with placebo, chlorthalidone has small effects on fasting glucose and total cholesterol, and compared with HCTZ, chlorthalidone achieves significantly lower total cholesterol and low-density lipoprotein cholesterol levels. Similarly, indapamide has demonstrated no negative impact on glucose or lipid metabolism. More importantly, although head-to-head clinical trials comparing the effects of indapamide or chlorthalidone with HCTZ are not available, indirect comparisons and post hoc analyses suggest that the use of chlorthalidone or indapamide is associated with a reduction in cardiovascular events. Despite this, the most frequent diuretic used in clinical practice as add-on therapy for hypertension is HCTZ. The purpose of this review is to update the published data on the efficacy and safety of HCTZ, chlorthalidone, and indapamide as add-on therapy in patients with hypertension.