Intensity of swimming exercise influences aortic reactivity in rats

Exercise is known to cause a vasodilatory response; however, the correlation between the vasorelaxant response and different training intensities has not been investigated. Therefore, this study evaluated the vascular reactivity and lipid peroxidation after different intensities of swimming exercise in rats. Male Wistar rats (aged 8 weeks; 250-300 g) underwent forced swimming for 1 h whilst tied to loads of 3, 4, 5, 6, and 8% of their body weight, respectively (groups G3, G4, G5, G6 and G8, respectively; n=5 each). Immediately after the test, the aorta was removed and suspended in an organ bath. Cumulative relaxation in response to acetylcholine (10−12-10−4 M) and contraction in response to phenylephrine (10−12-10−5 M) were measured. Oxidative stress was estimated by determining malondialdehyde concentration. The percentages of aorta relaxation were significantly higher in G3 (7.9±0.20), G4 (7.8±0.29), and G5 (7.9±0.21), compared to the control group (7.2±0.04), while relaxation in the G6 (7.4±0.25) and G8 (7.0±0.06) groups was similar to the control group. In contrast, the percentage of contraction was significantly higher in G6 (8.8 ±0.1) and G8 (9.7±0.29) compared to the control (7.1±0.1), G3 (7.3±0.2), G4 (7.2±0.1) and G5 (7.2±0.2%) groups. Lipid peroxidation levels in the aorta were similar to control levels in G3, G4 and G5, but higher in G6 and G8, and significantly higher in G8 (one-way ANOVA). These results indicate a reduction in vasorelaxing activity and an increase in contractile activity in rat aortas after high-intensity exercise, followed by an increase in lipid peroxidation.

β-Citronellol, an alcoholic monoterpene with inhibitory properties on the contractility of rat trachea

β-Citronellol is an alcoholic monoterpene found in essential oils such Cymbopogon citratus (a plant with antihypertensive properties). β-Citronellol can act against pathogenic microorganisms that affect airways and, in virtue of the popular use of β-citronellol-enriched essential oils in aromatherapy, we assessed its pharmacologic effects on the contractility of rat trachea. Contractions of isolated tracheal rings were recorded isometrically through a force transducer connected to a data-acquisition device. β-Citronellol relaxed sustained contractions induced by acetylcholine or high extracellular potassium, but half-maximal inhibitory concentrations (IC50) for K+-elicited stimuli were smaller than those for cholinergic contractions. It also inhibited contractions induced by electrical field stimulation or sodium orthovanadate with pharmacologic potency equivalent to that seen against acetylcholine-induced contractions. When contractions were evoked by selective recruitment of Ca2+ from the extracellular medium, β-citronellol preferentially inhibited contractions that involved voltage-operated (but not receptor-operated) pathways. β-Citronellol (but not verapamil) inhibited contractions induced by restoration of external Ca2+ levels after depleting internal Ca2+ stores with the concomitant presence of thapsigargin and recurrent challenge with acetylcholine. Treatment of tracheal rings with L-NAME, indomethacin or tetraethylammonium did not change the relaxing effects of β-citronellol. Inhibition of transient receptor potential vanilloid subtype 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1) receptors with selective antagonists caused no change in the effects of β-citronellol. In conclusion, β-citronellol exerted inhibitory effects on rat tracheal rings, with predominant effects on contractions that recruit Ca2+ inflow towards the cytosol by voltage-gated pathways, whereas it appears less active against contractions elicited by receptor-operated Ca2+ channels.

Calcium citrate improves the epithelial-to-mesenchymal transition induced by acidosis in proximal tubular cells

INTRODUCTION: Epithelial-to-mesenchymal transition (EMT) is a key event in renal fibrosis. The aims of the study were to evaluate acidosis induced EMT, transforming-growth-factor (TGF) β1 role and citrate effect on it. METHODS: HK2 cells (ATCC 2290) were cultured in DMEM/HAM F12 medium, pH 7.4. At 80% confluence, after 24 hr under serum free conditions, cells were distributed in three groups (24 hours): A) Control: pH 7.4, B) Acidosis: pH 7.0 and C) Calcium citrate (0.2 mmol/L) + pH 7.0. Change (Δ) of intracellular calcium concentration, basal and after Angiotensin II (10-6M) exposition, were measured to evaluate cellular performance. EMT was evaluated by the expression of α-smooth muscle actin (α-SMA) and E-cadherin by immunocytochemistry and/or Western blot. TGF-β1 secretion was determined by ELISA in cell supernatant. RESULTS: At pH 7.0 HK2 cells significantly reduced E-cadherin and increased α-SMA expression (EMT). Supernatant TGF-β1 levels were higher than in control group. Calcium citrate decreased acidosis induced EMT and improved cells performance, without reduction of TGF-β production. CONCLUSIONS: Acidosis induces EMT and secretion of TGF-β1 in tubular proximal cells in culture and citrate improves cellular performance and ameliorates acidosis induced EMT.