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There is a great urgency of detecting and monitoring myocardial fibrosis in clinical practice with the aim to improve and personalize therapy against cardiac remodelling. Hence, the aim of this study was to describe alterations in and show potential correlations between the structural characteristics and the molecular and biochemical markers of cardiac remodelling on a model of isoproterenol-induced heart failure. Two groups of 3-month-old male Wistar rats (n = 8 per group) were sacrificed after four weeks of treatment: control (placebo), ISO (5 mg/kg/day intraperitoneally). Chronic ISO treatment led to heart failure (HF) characterized by significant reduction of systolic blood pressure (SBP) accompanied by an increase in left ventricular weight (LVW) along with increased collagen content in the LV. The collagen content correlated negatively with SBP (R = -0.776, P < 0.001) and positively with LVW (R = 0.796, P < 0.001), with Col1a1 (0.83; P < 0.001) and Acta2 (0.73; P < 0.01). Moreover, the mRNA expression of fibrotic remodelling indicator, i.e. TGF-β1 tended to increase, while the level of fibrinolysis markers (MCP-1, TIMP-2, MMP) were unchanged. The plasma markers of collagen, procollagen I C-terminal propeptide (PICP) was 37.34 ± 7.10 pg/mL in control and was reduced by 42% (P < 0.05) in the ISO group and procollagen III N-terminal propeptide (PIIINP) was 1216.7 ± 191.0 pg/mL in control and was decreased by 66% (P < 0.05) in the ISO group. Surprisingly, there was no positive correlation between plasma markers of collagen, i.e. PICP and PIIINP and collagen content or molecular markers of collagen. However, both PICP and PIIINP correlated with BW (R = 0.712, resp. 0.803, P < 0.001), which was significantly reduced (by 25%, P < 0.05) in the ISO group. In conclusion, we assume that the collagen content of the left ventricle does not need unavoidably correlate with plasma markers of collagen, which might be affected by confounding factors in heart failure, such as loss of body weight, presumably associated with a catabolic condition. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases including hypertension are often associated with behavioural alterations. The aim of this study was to show, whether ivabradine, the blocker of If-channel in sinoatrial node, is able to modify the behaviour of rats in L-nitro-arginine methyl ester (L-NAME)-induced hypertension and to compare the effect of ivabradine with captopril and melatonin. 12-week-old male Wistar rats were divided into the following groups: controls, ivabradine (10 mg/kg/24 h), L-NAME (40 mg/kg/24 h), L-NAME + ivabradine, L-NAME + captopril (100 mg/kg/24 h), L-NAME + melatonin (10 mg/kg/24 h). Systolic blood pressure (SBP) and heart rate (HR) were measured by tail-cuff method once a week. The behaviour of rats was investigated during 23-hours in the phenotyper after four weeks of the treatment. Chronic administration of L-NAME induced hypertension without a change in HR. All tested substances partly prevented the increase of SBP, while ivabradine and melatonin also reduced HR. Ivabradine, captopril and melatonin reduced daily food intake, slightly decreased daily water intake and attenuated body weight gain. In L-NAME group, locomotor activity was enhanced by ivabradine, whereas exploratory behaviour was increased by melatonin and captopril. In conclusion, ivabradine, besides its potentially protective hemodynamic actions, does not seem to exert any disturbing effects on behaviour in L-NAME-induced hypertension in rats, while some of its effects were similar to captopril or melatonin. It is suggested that ivabradine used in cardiovascular indications is harmless regarding the effect on behaviour.

The multimarker approach using Luminex technology represents a new tool for studying the pathogenesis of cardiovascular disease. Although many cardiac biomarkers in heart failure have been well established, the role and significance of their measurement in hypertensive patients is still questionable. The aim of our study was to evaluate the relationship of selected biomarkers in L-NAME-induced hypertension to the left ventricular remodeling in the two different periods of hypertension development. Four groups of 3-month-old male Wistar rats were investigated: (1) control 4 (placebo for 4 weeks), (2) control 7 (placebo for 7 weeks), (3) L-NAME 4 (40 mg/kg/day for 4 weeks), and (4) L-NAME 7 (40 mg/kg/day for 7 weeks). BNP, cTnI, TNF-α, and VEGF were measured using Rat CVD Panel 1 Kit (Milliplex® MAP). Cardiac troponin T was determined using Elecsys® Troponin T high sensitive immunoassay (Roche, Switzerland). Although the systolic blood pressure increases about 50% in L-NAME-induced hypertension in rat, both hypertrophy and fibrosis were expressed only slightly in this experiment. The levels of BNP, TNF-α, or VEGF did not differ significantly among groups. However, cardiac troponin T measured by high sensitive ELISA was significantly (P<0.05) increased in L-NAME 4 (0.229 μg/l versus 0.034 μg/l) and L-NAME-7 groups (0.366 μg/l versus 0.06 μg/l) in comparison with the controls. We conclude that the slightly increased cTnT levels could indicate ischemic damage of L-NAME-hypertensive heart. Importantly, to our best knowledge, this is the first study indicating that CVD rat panel may be a useful methodological tool in experimental cardiology.