Effect of the level of magnesium in drinking water on the state of the cardiovascular system of spontaneous hypertensive rats

INTRODUCTION. Magnesium is the second most common intracellular cation, is a cofactor for more than 300 enzymes, affects the functional state of the cardiovascular system through various mechanisms, in particular, through the action on the smooth muscle cells of the vessels, modulation of the renin-angiotensin-aldosterone system, regulation of sodium and calcium homeostasis. Therefore, maintaining a normal level of magnesium in the blood is an urgent task, and the consumption of drinking water enriched with magnesium can be considered as a method of correcting an insufficient intake of exogenous magnesium.THE AIM. The purpose of the study was determined – to evaluate the effect of drinking water with different contents of magnesium ions and a complex of magnesium with calcium on the state of the cardiovascular system of rats with genetically determined arterial hypertension. MATERIALS AND METHODS. From 6–7 weeks of age, male SHR rats received drinking water of various compositions for two months: in the first group (hCа+Mg) – with increased content of calcium and magnesium (120 mg/l Ca2+ and 45 mg/l Mg2+), the second (nCа+Mg) – drinking water normalized by mineral composition (60 mg/l Ca2+ and 25 mg/l Mg2+), in the third (hMg) – enriched Mg2+ (45 mg/l), the fourth (control) control group – St. Petersburg tap water with a low mineral content (8 mg/l Ca2+ and 3 mg/l Mg2+). WKY rats were divided into 2 groups: one group (hMg) received water enriched with Mg2+ (45 mg/l), the control WKY (control) group received water with a low mineral content (8 mg/l Ca2+ and 3 mg/l Mg2+). After 2 months, the blood pressure of rats on the tail was measured by the cuff method, the level of urea, cholesterol, total calcium, and albumin in the blood serum was analyzed, left ventricular mass index (LVMI) and myocardial mass index (MMI) were calculated. The spontaneous contractile activity of the portal vein (PV) was recorded by myography (in vitro) in isometric mode. The following were analyzed: frequency, total and maximum amplitude of phase-tonic contractions, the area under the contraction curve in 1 min, which characterizes the work performed by the vein. %). RESULTS. Enrichment of drinking water with Ca2+ and Mg2+ had a more pronounced antihypertensive effect in SHR rats compared with the hMg2+ group. In WKY rats, magnesium enrichment of water did not affect blood pressure. Modification of the mineral composition of drinking water did not affect MMI and LVMI in both SHR and WKY rats. Interlinear differences were found in the contractile activity of PV in control rats (the amplitude of PV contractions in SHR rats was greater than WKY. Consumption of water enriched with minerals decreased the amplitude of PV contractions, the largest decrease was in the hMg2+ group (in SHR, 2.6 times, in WKY, 1.5 times as compared to the control of the corresponding line). The value of the work performed by the PV in the control SHR rats was greater than in the control rats of the WKY line, and the enrichment of water with magnesium caused a decrease in the work performed by the PV only in rats SHR lines (by 55.6 %), but not for WKY. CONCLUSIONS. In rats, the consumption of drinking water enriched only with magnesium has an antihypertensive effect; however, it suppresses the spontaneous contractile activity of PV. It is advisable to use a complex of magnesium with calcium, which lowers blood pressure, but maintains an adequate level of contractile activity of the PV.

A Network Pharmacology-based Approach to Explore the Active Ingredients and Molecular Mechanism of Lei-gong-gen Formula Granule on a Spontaneously Hypertensive Rat Model

Background Lei-gong-gen formula granule (LFG) is a folk prescription derived from Zhuang nationality, which is the largest ethnic minority among the 56 nationalities in China. It consists of three herbs, namely Eclipta prostrata (L.) L., Smilax glabra Roxb, and Centella asiatica (L.) Urb. It has been widely used as health protection tea for hundreds of years to prevent hypertension in Guangxi Zhuang Autonomous Region. The purpose of this study is to validate the antihypertensive effect of LFG on a SHR model and further to identify the active ingredients of LFG and its anti-hypertension molecular mechanism. Methods Firstly, a spontaneously hypertensive rat model was used to observe the effects of LFG on blood pressure, body weight, and heart rate. The serum levels of NO, ANG Ⅱ, and ET-1 were measured and H&E staining was applied to observe the pathology of the heart. Secondly, network pharmacology analysis was performed to collect the ingredients of LFG by using the database of traditional Chinese medicine (TCMSP, TCMID, BATMAN-TCM) and to predict the active compounds, their corresponding targets, and hypertension associated pathways. Then the predicted results were verified by molecular biology experiments such as RT-qPCR and western blot. Finally, the potential active compounds were predicted by molecular docking technology, and the LFG chemical constituents were analyzed and identified by UPLC-QTOF/MS technology. Results LFG significantly reduced blood pressure and increased serum NO content in SHR rats. LFG ameliorated the pathological changes such as cardiac hypertrophy and interstitial inflammation. Based on the results of public database searching, 53 candidate active compounds from LFG were collected, which link to 765 potential targets. 828 hypertension associated targets were retrieved. 12 overlapped targets both related to candidate active compounds from LFG and hypertension were screened and used as the potential targets of LFG on antihypertensive effect. And the 12 overlapped targets were validated using RT-qPCR, and the results showed that LFG could upregulate the mRNA expression of NOS3 and proto-oncogene tyrosine-protein kinase SRC (SRC) in the thoracic aorta. Pathway enrichment results showed that PI3K-AKT signaling pathway was closely related to the expression of NOS3 and SRC. To verify this result, western blot was used to detect the key proteins (PI3K, AKT, and p-AKT) of the PI3K-AKT signaling pathway. The results showed that LFG significantly increased the protein expression levels of PI3K and phosphorylated AKT in SHR rats, suggesting that LFG may active PI3K-AKT signaling pathway to decrease hypertension. Molecular docking study further supported that p-hydroxybenzoic acid, cedar acid, shikimic acid, salicylic acid, nicotinic acid, linalool, and histidine can be well binding with NOS3, SRC, PI3K, and AKT. UPLC-QTOF/MS analysis confirmed that p-hydroxybenzoic acid, shikimic acid, salicylic acid, and nicotinic acid existed in LFG. Conclusion LFG can reduce the blood pressure of SHR rats, which might be attributed to increasing the serum NO level for promoting vasodilation via upregulating SRC expression level and activating the PI3K-AKT-NOS3 signaling pathway. p-Hydroxybenzoic acid, shikimic acid, salicylic acid, and nicotinic acid might be the underlying compounds for LFG antihypertensive effect.

CHARACTERISTIC OF AGE-DEPENDENT CHANGES IN PIAL ARTERIAL VESSELS ENDOTHELIUM-DEPENDENT HYPERPOLARIZATION IN NORMOTENSIVE AND SPONTANEOUSLY HYPERTENSIVE RATS

Изучено изменение роли эндотелиальной гиперполяризации ( EDH ) в эндотелий-зависимой регуляции тонуса мозговых сосудов при старении в отсутствии и в условиях длительно текущей артериальной гипертензии (АГ). Исследовали роль EDH , индуцируемой активацией IK -каналов, и NO в дилатации пиальных артериальных сосудов на ацетилхолин у нормотензивных ( WKY ) и спонтанно гипертензивных крыс ( SHR ) в возрасте 4 и 18 мес. Установлено, что у крыс WKY механизм EDH преимущественно выражен в группе мелких сосудов. В процессе старения происходит снижение вклада EDH в осуществление дилатации мелких и средних сосудов с одновременным его повышением у артерий диаметром более 40 мкм. АГ приводит к повышению вклада процессов EDH в дилатацию сосудов мелкого и среднего диаметра. Старение, сопровождаемое длительно текущей АГ, снижает вклад EDH в дилатацию. У 18-месячных крыс SHR этот механизм выражен только в группе мелких сосудов диаметром менее 20 мкм. В основе возрастных изменений роли механизмов EDH в дилататорных ответах сосудов у крыс WKY и SHR лежит нарушение системы синтеза NO и изменение роли NO -опосредованных механизмов в эндотелийзависимой вазодилатации. A comparative study of changes in the contribution of endothelium-dependent hyperpolarization (EDH) induced by activation of the intermediate-conductance calcium-activated potassium channels ( IK ) channels and the contribution of NO in pial arterial vessels dilation to acetylcholine (ACh) in normotensive ( WKY ) and spontaneously hypertensive ( SHR ) rats at the age of 4 and 18 months was conducted. It was found that in WKY , the EDH is mainly expressed in the group of small pial arterial vessels. During aging, the contribution of EDH to the dilatation of small (diameter less than 20 microns) and medium (20-40 microns) vessels decreases, while it increases in arteries with a diameter of more than 40 microns. Hypertension (HT) leads to an increase in the contribution of EDH processes to dilation of vessels of small and medium diameters. Aging, accompanied by long-term HT, reduces the contribution of EDH to dilation. In 18-month-old SHR, this mechanism is expressed only in a group of small vessels. Age-dependent changes in the EDH contribution in pial arterial vessels dilation in WKY and SHR rats are based on the NO synthesis system damage and a change in the NO -mediated contribution in endothelium-dependent vasodilation.

Acacetin improves endothelial dysfunction and aortic fibrosis in insulin-resistant SHR rats by estrogen receptors

The aim of the work was to investigate the effects of acacetin on endothelial dysfunction and aortic fibrosis in insulin-resistant SHR rats and explore its mechanism. Seven-week-old male spontaneously hypertensive rats (SHR) were selected to establish a rat model of hypertension with insulin resistance induced by 10% fructose. The nuclear factor kappa B p65 (NF-κB p65) and Collagen I were observed by Immunohistochemistry. Immunofluorescence was used to observe estrogen receptor-alpha (ERα), estrogen receptor-beta (ERβ), and G protein-coupled receptor 30 (GPR30). Western blotting was used to detect interleukin (IL-1β), Arginase 2 (ARG2), Nostrin, endothelial nitric oxide synthase (eNOS), TGF-β, Smad3, ERK pathway proteins such as p-c-Raf, p-MEK1/2, p-ERK, ERK, p-P90RSK and p-MSK1. We found that acacetin did have an improvement on endothelial dysfunction and fibrosis. Meanwhile, it was also found to have a significant effect on the level of estrogen in this model by accident. Then, the experiment of uterine weight gain in mice confirmed that acacetin had a certain estrogen-like effect in vivo and played its role through the estrogen receptors pathway. In vitro experience HUVEC cells were stimulated with 30 mM/L glucose and 100 mM/L NaCl for 24 h to establish the endothelial cell injury model. HUVEC cells were treated with 1 μM/L estrogen receptors antagonist (ICI 182780) for 30 min before administration. Cell experiments showed that acacetin could reduce the apoptosis of HUVEC cells, the levels of inflammatory cytokines and the expression of TGF-β, Collagen I and Smad3 in endothelial cell injury model. After treatment with ICI 182780, the improvement of acacetin was significantly reversed. The results showed that acacetin relieved endothelial dysfunction and reduced the aortic fibrosis in insulin-resistant SHR rats by reducing the release of inflammatory factors and improving vasodilatory function through estrogen signaling pathway.