NETosis Drives Blood Pressure Elevation and Vascular Dysfunction in Hypertension.

BACKGROUND: Neutrophil extracellular traps (NETs) are composed of nDNA, enzymes, and citrullinated histones that are expelled by neutrophils in the process of NETosis. NETs accumulate in the aorta and kidneys in hypertension. PAD4 (protein-arginine deiminase-4) is a calcium-dependent enzyme that is essential for NETosis. TRPV4 (transient receptor potential cation channel subfamily V member 4) is a mechanosensitive calcium channel expressed in neutrophils. Thus, we hypothesize that NETosis contributes to hypertension via NET-mediated endothelial cell (EC) dysfunction. METHODS: NETosis-deficient Padi4-/- mice were treated with Ang II (angiotensin II). Blood pressure was measured by radiotelemetry, and vascular reactivity was measured with wire myography. Neutrophils were cultured with or without ECs and exposed to normotensive or hypertensive uniaxial stretch. NETosis was measured by flow cytometry. ECs were treated with citrullinated histone H3, and gene expression was measured by quantitative RT-PCR. Aortic rings were incubated with citrullinated histone H3, and wire myography was performed to evaluate EC function. Neutrophils were treated with the TRPV4 agonist GSK1016790A. Calcium influx was measured using Fluo-4 dye, and NETosis was measured by immunofluorescence. RESULTS: Padi4-/- mice exhibited attenuated hypertension in response to Ang II, reduced aortic inflammation, and improved EC-dependent vascular relaxation. Coculture of neutrophils with ECs and exposure to hypertensive uniaxial stretch increased NETosis and accumulation of neutrophil citrullinated histone H3. Histone H3 and citrullinated histone H3 exposure attenuates EC-dependent vascular relaxation. Treatment of neutrophils with the TRPV4 agonist GSK1016790A increases intracellular calcium and NETosis. CONCLUSIONS: These observations identify a role of NETosis in the pathogenesis of hypertension. Moreover, they define an important role of EC stretch and TRPV4 as initiators of NETosis. Finally, they define a role of citrullinated histones as drivers of EC dysfunction in hypertension.

Recent Advances in Understanding Peripheral and Gut Immune Cell-Mediated Salt-Sensitive Hypertension and Nephropathy.

Hypertension is the primary modifiable risk factor for cardiovascular, renal, and cerebrovascular diseases and is considered the main contributing factor to morbidity and mortality worldwide. Approximately 50% of hypertensive and 25% of normotensive people exhibit salt sensitivity of blood pressure, which is an independent risk factor for cardiovascular disease. Human and animal studies demonstrate that the immune system plays an important role in the etiology and pathogenesis of salt sensitivity of blood pressure, kidney damage, and vascular diseases. Antigen-presenting and adaptive immune cells are implicated in salt-sensitive hypertension and salt-induced renal and vascular injury. Elevated sodium activates antigen-presenting cells to release proinflammatory cytokines including IL (interleukin) 6, tumor necrosis factor-α, IL-1ß, and accumulate isolevuglandin-protein adducts. In turn, these activate T cells release prohypertensive cytokines including IL-17A. Moreover, high-salt intake is associated with gut dysbiosis, leading to inflammation, oxidative stress, and blood pressure elevation but the mechanistic contribution to salt-sensitivity of blood pressure is not clearly understood. Here, we discuss recent advances in research investigating the cause, potential biomarkers, and therapeutic targets for salt-sensitive hypertension as they pertain to the gut microbiome, immunity, and inflammation.

Extract of Chenopodium album lowers blood pressure in rats through endothelium-dependent and -independent vasorelaxation.

OBJECTIVES: To investigate the antihypertensive effect of crude extract of Chenopodium album (Ca.Cr), based on its medicinal use in hypertension. METHODS: Ca.Cr and its fractions were tested in-vivo in normotensive anesthetized rats for blood pressure-lowering effect. In-vitro experiments were performed on isolated rat aortae to explore the vascular mechanism(s). RESULTS: In normotensive anesthetized rats, Ca.Cr produced a dose-dependent (1-300mg/kg) fall (30%mmHg) in mean arterial pressure (MAP). Among the fractions, nHexane was the most potent (46% fall). In rat aortic rings precontracted with phenylephrine (PE), Ca.Cr and its fractions (except Ca.Aq) produced endothelium-dependent vasorelaxation, which was partially reversed with endothelium removal and by pretreating intact aortic rings with L-NAME (10µM) and atropine (1µM). This relaxation to Ca.Cr and fractions (nHexane, ethylacetate and chloroform) was also eliminated with indomethacin pretreatment, however, it unmasked a vasoconstriction effect with Ca.Cr only. Surprisingly, the aqueous fraction produced a calcium sensitive strong vasoconstriction instead of vasorelaxation. The crude extract and its fractions (except Ca.Aq) also antagonized vasoconstriction induced with high K+ (80mM), suggesting calcium antagonistic effect. The aqueous fraction produced mild vasorelaxation against high K+. This effect was further confirmed when pretreatment of the aortic rings with different concentrations of crude extract and fractions suppressed CaCl2 concentration response curves, similar to verapamil. In acute toxicity test, Ca.Cr extract was found safe up to 5g/kg body weight in mice. CONCLUSION: These findings suggest that crude extract and fractions of C. album produced vasorelaxant effect through muscarinic receptors linked-NO pathway, prostaglandin (endothelium-dependent) and calcium antagonism (endothelium-independent), which explains the blood pressure lowering effect of C. album in rats.

The Antioxidative Effects of Flavones in Hypertensive Disease.

Hypertension is the leading remediable risk factor for cardiovascular morbidity and mortality in the United States. Excess dietary salt consumption, which is a catalyst of hypertension, initiates an inflammatory cascade via activation of antigen-presenting cells (APCs). This pro-inflammatory response is driven primarily by sodium ions (Na+) transporting into APCs by the epithelial sodium channel (ENaC) and subsequent NADPH oxidase activation, leading to high levels of oxidative stress. Oxidative stress, a well-known catalyst for hypertension-related illness development, disturbs redox homeostasis, which ultimately promotes lipid peroxidation, isolevuglandin production and an inflammatory response. Natural medicinal compounds derived from organic materials that are characterized by their anti-inflammatory, anti-oxidative, and anti-mutagenic properties have recently gained traction amongst the pharmacology community due to their therapeutic effects. Flavonoids, a natural phenolic compound, have these therapeutic benefits and can potentially serve as anti-hypertensives. Flavones are a type of flavonoid that have increased anti-inflammatory effects that may allow them to act as therapeutic agents for hypertension, including diosmetin, which is able to induce significant arterial vasodilation in several different animal models. This review will focus on the activity of flavones to illuminate potential preventative and potential therapeutic mechanisms against hypertension.

7-Hydroxy Frullanolide Ameliorates Isoproterenol-Induced Myocardial Injury through Modification of iNOS and Nrf2 Genes.

Myocardial infarction (MI) is the principal cause of premature death. Protecting myocardium from ischemia is the main focus of intense research. 7-hydroxy frullanolide (7-HF) is a potent anti-inflammatory agent, showing its efficacy in different acute and chronic inflammatory disorders such as atherosclerosis, suggesting it can be a potential cardioprotective agent. For the induction of MI, Sprague-Dawley rats (n = 5) were administered isoproterenol (ISO) 85 mg/kg s.c at 24 h intervals for two days. The potential cardioprotective effect of 7-HF and its mechanisms were explored by in vivo and in vitro methods. 7-HF significantly prevented the extent of myocardial injury by decreasing the infarct size, preserving the histology of myocardial tissue, and reducing the release of cardiac biomarkers. Further, 7-HF increased the mRNA expression of cardioprotective gene Nrf2 and reduced the mRNA expression of iNOS. 7-HF also improved cardiac function by decreasing the cardiac workload through its negative chronotropic and negative ionotropic effect, as well as by reducing peripheral vascular resistance due to the inhibition of voltage-dependent calcium channels and the release of calcium from intracellular calcium stores. In conclusion, 7-HF showed cardioprotective effects in the MI model, which might be due to modulating the expression of iNOS and Nrf2 genes as well as improving cardiac functions.

Antioxidant Flavonoid Diosmetin Is Cardioprotective in a Rat Model of Myocardial Infarction Induced by Beta 1-Adrenergic Receptors Activation.

Myocardial infarction (MI) is a common and life-threatening manifestation of ischemic heart diseases (IHD). The most important risk factor for MI is hypertension. Natural products from medicinal plants have gained considerable attention globally due to their preventive and therapeutic effects. Flavonoids have been found to be efficacious in ischemic heart diseases (IHD) by alleviating oxidative stress and beta-1 adrenergic activation, but the mechanistic link is not clear. We hypothesized that antioxidant flavonoid diosmetin is cardioprotective in a rat model of MI induced by beta 1-adrenergic receptor activation. To test this hypothesis, we evaluated the cardioprotective potential of diosmetin on isoproterenol-induced MI in rats by performing lead II electrocardiography (ECG), cardiac biomarkers including troponin I (cTnI) and creatinine phosphokinase (CPK), CK-myocardial band, (CK-MB), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and aspartate aminotranferase (AST) by using biolyzer 100, as well as histopathological analysis. We found that diosmetin (1 and 3 mg/kg) attenuated isoproterenol-induced elevation in the T-wave and deep Q-wave on the ECG, as well as heart-to-body weight ratio and infarction size. In addition, pretreatment with diosmetin attenuated the isoproterenol-induced increase in serum troponin I. These results demonstrate that flavonoid diosmetin may provide therapeutic benefit in myocardial infarction.

The epithelial sodium channel in inflammation and blood pressure modulation.

A major regulator of blood pressure and volume homeostasis in the kidney is the epithelial sodium channel (ENaC). ENaC is composed of alpha(α)/beta(ß)/gamma(γ) or delta(δ)/beta(ß)/gamma(γ) subunits. The δ subunit is functional in the guinea pig, but not in routinely used experimental rodent models including rat or mouse, and thus remains the least understood of the four subunits. While the δ subunit is poorly expressed in the human kidney, we recently found that its gene variants are associated with blood pressure and kidney function. The δ subunit is expressed in the human vasculature where it may influence vascular function. Moreover, we recently found that the δ subunit is also expressed human antigen presenting cells (APCs). Our studies indicate that extracellular Na+ enters APCs via ENaC leading to inflammation and salt-induced hypertension. In this review, we highlight recent findings on the role of extra-renal ENaC in inflammation, vascular dysfunction, and blood pressure modulation. Targeting extra-renal ENaC may provide new drug therapies for salt-induced hypertension.

Antidiarrheal, antisecretory and intestinal smooth muscle relaxant effects of Platanus orientalis in mice.

Platanus orientalis is traditionally used to treat diarrhea and spasm. However, studies are lacking on its mechanism of action in diarrhea and spasm. Pharmacological in-vivo activities were performed. In-vitro activities were carried out to explore the underlying mechanism(s) of action in isolated tissue preparations of mice jejunum and ileum. Crude extract of Platanus orientalis, loperamide and verapamil were used. The crude extract provided dose-dependent protection in castor oil diarrhea like verapamil and reduced the intestinal fluid accumulation and charcoal meal transit distance. In-vitro studies produced spasmolytic effect on the spontaneous (EC50 value=0.21mg/mL), high K+ (EC50 value=0.37mg/mL) and carbachol (CCh)-induced contractions 5.35mg/mL (3.88-6.85) respectively. The quiescent ileum responded well to the high K+ and carbachol (CCh)-induced contractions when tested against crude extract. It caused inhibition of the induced contraction with EC50 values of 0.20mg/mL (0.10-0.30) and 3.25mg/mL (2-4.5) respectively and showed potent effect against CCh-induced contractions. Calcium response curves produced a similar effect to verapamil. The crude extract of Platanus orientalis remained safe up to 5g/kg dose.

Blood pressure-lowering and cardiovascular effects of plumbagin in rats: An insight into the underlying mechanisms.

Background: Plumbagin, a natural phenolic compound is investigated for response against blood pressure and vascular reactivity. Methodology: Blood pressure lowering effects were observed by in-vivo invasive evaluation in normotensive rats, and in-vitro experimentation to measure changes of tension in isolated rat aorta and contractility in atria. Results: The percentage decrease in mean arterial pressure (MAP) observed with plumbagin intravenously at doses of 0.1, 0.5, 1, 5, 10 â€‹µg/kg in normotensive rats was 7.16 â€‹± â€‹2.35, 15.5 â€‹± â€‹5.62, 19.5 â€‹± â€‹5.27, 26 â€‹± â€‹6.67, 34.33 â€‹± â€‹8.80, respectively. Plumbagin exerted vasorelaxant effects in rat aorta, unaffected by the removal of vascular endothelium, and L-NAME and methylene blue pretreatment. Plumbagin completely inhibited phenylephrine (1 â€‹µM) and High K+ (80 â€‹mM) induced contractions. Similar to a Ca+2 channel antagonist, plumbagin caused a rightward shift in the Ca+2 concentration-response-curves (CRCs), resembling nifedipine. Pre-incubation with plumbagin, significantly suppressed contractions induced by phenylephrine in Ca+2-free medium via disrupting Ca+2 release from intracellular stores. No change in vasorelaxant response was observed with the addition of potassium channel blockers, TEA and BaCl2. In rat atrial strips, plumbagin exerted significant negative inotropic and chronotropic effects. No significant change was observed with atropine and atenolol pretreatment, so the effect appeared independent of muscarinic and beta-adrenergic receptors. Conclusion: This study suggests the blood pressure lowering effects of plumbagin. That could be contributed by a decrease in vascular resistance via calcium antagonism, interferences in calcium efflux, and depressive effects on the rate and force of cardiac contraction. Further studies would be necessary to probe deeper into the underlying mechanisms.

Vasorelaxant and Antihypertensive Effects of Bergenin on Isolated Rat Aorta and High Salt-Induced Hypertensive Rats.

Bergenin is a phenolic glycoside that has been reported to be present in some medicinal plants which are traditionally used for their antihypertensive actions. So, bergenin was investigated for antihypertensive and vasorelaxant experiments in a rat model. Bergenin produced a significant fall in the mean arterial pressure (MAP) of rats. To explore the involvement of NO and muscarinic receptors, rats were pretreated with L-NAME and atropine in-vivo. The L-NAME did not change significantly the effect of bergenin on MAP excluding the involvement of NO. Unlike the L-NAME, atropine pretreatment reduced the effect of bergenin on MAP, indicating the role of muscarinic receptors. In in-vitro study, the bergenin produced endothelium-dependent (at lower concentrations) and independent (at higher concentrations) vasorelaxation, which was attenuated significantly in the presence of atropine and indomethacin but not with L-NAME. While a partial response was observed against K+-induced contractions. This was further confirmed when bergenin partly shifted the CaCl2-CRCs toward right. Bergenin also suppressed the PE peak formation, indicating the antagonist effect against the release of Ca2+. Moreover, the bergenin-induced vasorelaxant response was not markedly attenuated with TEA, while significantly ablated with 4-AP and BaCl2. In conclusion, the antihypertensive effects of bergenin are due to Ca2+ channel blockade, K+ channels activation, and muscarinic receptor-linked vasodilation.

Investigation into the Antihypertensive Effects of Diosmetin and Its Underlying Vascular Mechanisms Using Rat Model.

OBJECTIVE: Diosmetin is a flavonoid that is found in many important medicinal plants that have antihypertensive therapeutic potential. Diosmetin has been shown to have antiplatelet, anti-inflammatory and antioxidant properties, which suggests that it could be a potential candidate for use in antihypertensive therapy. METHODS: In vivo and in vitro methods were used for our investigation into the antihypertensive effects of diosmetin. RESULTS: Diosmetin significantly decreased the mean arterial pressure (MAP). The effects of diosmetin on the MAP and heart rate were more pronounced in hypertensive rats. To explore the involvement of the muscarinic receptors-linked NO pathway, Nω-nitro-L-arginine methyl ester (L-NAME) and atropine were pre-administered in vivo. The pretreatment with L-NAME did not significantly change the effects of diosmetin on the MAP by excluding the involvement of NO. Unlike L-NAME, the atropine pretreatment reduced the effects of diosmetin on the MAP, which demonstrated the role of the muscarinic receptors. In the in vitro study, diosmetin at lower concentrations produced endothelium-dependent and -independent (at higher concentrations) vasorelaxation, which was attenuated significantly by the presence of atropine and indomethacin but not L-NAME. Diosmetin was also tested for high K+-induced contractions. Diosmetin induced significant relaxation (similar to verapamil), which indicated its Ca2+ antagonistic effects. This was further confirmed by diosmetin shifting the CaCl2 CRCs toward the right due to its suppression of the maximum response. Diosmetin also suppressed phenylephrine peak formation, which indicated its antagonist effects on the release of Ca2+. Moreover, BaCl2 significantly inhibited the effects of diosmetin, followed by 4-AP and TEA, which suggested that the K+ channels had a role as well. CONCLUSIONS: The obtained data showed the Ca2+ channel antagonism, potassium channel activation and antimuscarinic receptor-linked vasodilatory effects of diosmetin, which demonstrated its antihypertensive potential.

Juglone from Walnut Produces Cardioprotective Effects against Isoproterenol-Induced Myocardial Injury in SD Rats.

Therapeutic and/or preventive interventions using phytochemical constituents for ischemic heart disease have gained considerable attention worldwide, mainly due to their antioxidant activity. This study investigated the cardioprotective effect and possible mechanism of juglone, a major constituent of the walnut tree, using an isoproterenol (ISO)-induced myocardial infarction (MI) model in rats. Rats were pretreated for five (5) days with juglone (1, 3 mg/kg, i.p) and atenolol (1 mg/kg, i.p) in separate experiments before inducing myocardial injury by administration of ISO (80 mg/kg, s.c) at an interval of 24 h for 2 consecutive days (4th and 5th day). The cardioprotective effect of juglone was confirmed through a lead II electrocardiograph (ECG), cardiac biomarkers (cTnI, CPK, CK-MB, LDH, ALT and AST) and histopathological study. The results of our present study suggest that prior administration of juglone (1 and 3 mg/kg) proved to be effective as a cardioprotective therapeutic agent in reducing the extent of myocardial damage (induced by ISO) by fortifying the myocardial cell membrane, preventing elevated T-waves, deep Q-waves in the ECG, heart to body weight ratio, infarction and also by normalizing cardiac marker enzymes (cTnI, CPK, CK-MB, LDH, ALT and AST) and histopathological changes, such as inflammation, edema and necrosis. In conclusion, this study has identified phytochemical constituents, in particular juglone, as a potential cardioprotective agent.

Cardioprotective Potential of Aqueous Extract of Fumaria indica on Isoproterenol-Induced Myocardial Infarction in SD Rats.

Ischemic heart disease (IHD) treatments and preventions by using plant extract and its phytochemical constituents have achieved considerable attention globally due to its cardioprotective effects. This study is aimed at investigating the cardioprotective and vascular effects of Fumaria indica (F. indica) crude extract on isoproterenol- (ISO-) induced myocardial infarction (MI) in Sprague-Dawley (SD) rats. Rats treated with isoproterenol (85 mg/kg, s.c), administered. Twice at an interval of 24 h showed a significant ST-segment elevation in ECG, edema, and necrosis in histopathology and also in troponin I (cTnI), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and aspartate aminotransferase (AST). Pretreatment with F. indica (10, 30, and 100 mg/kg, p.o) for 21 days significantly reversed the effects of isoproterenol-induced ischemic changes in the ECG, levels of cTnI, CPK, LDH, and AST, and histopathological changes. In isolated rat atrial strips, F. indica induced negative chronotropic and inotropic effects which were not affected by pretreatment with atropine, excluding role of cardiac muscarinic receptors. Cumulative addition of the extract induced a vasorelaxant effect on phenylephrine-evoked contractions in isolated rat aortic rings, which remained unchanged when challenged with L-NAME, excluding role of endothelial NO. However, extract of F. indica concentration dependently reversed contractions evoked with high K+, indicating calcium entry blocking effect. In conclusion, the F. indica extract is a cardioprotective remedy that ameliorates the isoproterenol-induced cardiotoxic effects and reverses cardiac ischemia, and the calcium antagonistic effect might be of useful in the treatment of MI.

Antihypertensive effect and the underlying mechanisms of action of phytolaccagenin in rat models.

BACKGROUND: Phytolaccagenin, a natural triterpenoid, is reported for various biological activities that indicate its potential role in the management of hypertension. METHODS: Phytolaccagenin was evaluated for its antihypertensive activity in rat models via in vivo and in vitro experiments using polyethylene tubings for cannulation, organ bath bubbled with carbogen gas, and a pressure transducer connected to a PowerLab data acquisition system. RESULTS: Intravenous administration of phytolaccagenin decreased mean arterial pressure (MAP), significantly, in normotensive and hypertensive anesthetized rats. Pretreatment of rats with atropine (2 mg/kg) partially reversed the decrease in blood pressure due to phytolaccagenin at first tested doses. However, Nω-nitro-L-arginine methyl ester (L-NAME) (100 mg/kg) pretreatment modified the effect of phytolaccagenin on blood pressure with greater response. In isolated rat aortic rings precontracted with phenylephrine, cumulative addition of phytolaccagenin induced relaxation that is ablated (50%) with denudation and pre-incubation with atropine (1 µM) and L-NAME (10 µM). Phytolaccagenin also partially inhibited high K+ precontraction at initial doses, while an inhibitory effect was observed at higher concentrations, confirming its effect on voltage-dependent calcium channels. In isolated spontaneously beating rat atrial strips, phytolaccagenin suppressed the atrial tone that was reduced with isoprenaline and atropine pre-incubation, suggesting the role of cardiac adrenergic and muscarinic receptors. Interestingly, atenolol (1 µM) pretreatment also ablated the cardiac effects of phytolaccagenin. CONCLUSION: The antihypertensive effect of phytolaccagenin is due to a decrease in vascular resistance and cardiac depressant effects. These effects are mediated via muscarinic receptors-linked NO pathway, inhibitory effect on Ca2+ movements (vascular), and activation of cardiac muscarinic and blockade of ß-adrenergic receptors.

Evaluation of the Antiasthmatic Activity of Carissa opaca in Animal Models.

Carissa opaca Stapf ex Haines (C. opaca) fruit is used traditionally in the treatment of respiratory illnesses including asthma. However, there is no scientific evidence supporting its antiasthmatic activity. The current study was conducted to evaluate its antiasthmatic effects using in vivo and in vitro approaches. The methanolic crude extract of C. opaca fruit (Co.Cr.) was used and in vivo antiasthmatic activity was carried out using ovalbumin- (OVA-) sensitized and OVA-challenged BALB/c mice. In in vitro bronchorelaxant activity of crude extract, aqueous and n-hexane fractions of C. opaca were carried out on isolated rat tracheal strips. Co.Cr. (200 and 400 mg/kg) attenuated ovalbumin-induced changes in lung histochemistry with % decrease in peribronchial inflammation of 14.1 ± 0.21 and 65.8 ± 0.22 and % decrease in total inflammatory cell count of 35.7 ± 2.80 and 53.3 ± 2.30 in bronchoalveolar lavage fluid. Co.Cr., aqueous, and n-hexane fraction of C. opaca attenuated the precontractions induced by high K+ (80 mM) and carbachol (1 µM), respectively. In conclusion, the results showed that C. opaca possesses antiasthmatic activity via relaxant effect on bronchial smooth muscle which is mediated through calcium channel blockade and antimuscarinic activity. This study provides scientific evidence of the traditional use of C. opaca in the management of allergic asthma.

Insight into the cardiovascular mechanisms of blood pressure lowering effect of gitogenin: a steroidal saponin.

Background/objectives: Steroidal saponins are widely distributed in medicinal plants with potential applications in cardiovascular disorders. Gitogenin, a saponin, has not been explored as antihypertensive; this investigation was aimed to explore its blood pressure lowering potential and underlying mechanisms.Methodology: The effect of gitogenin was evaluated on blood pressure in vivo, using normotensive rat model and the underlying cardiovascular mechanism(s) in vitro, in isolated rat aorta and in atria preparations using PowerLab data acquisition system (ADInstrument, Australia).Results: Intravenous injection of gitogenin decreased mean arterial pressure (MAP) in anesthetized rats. Atropine (1 mg/kg) and L-NAME (100 mg/kg) pretreatment significantly (*p < .05) attenuated effect on MAP to gitogenin. In isolated intact aortic rings, gitogenin induced endothelium-dependent vasodilatation (maximum 65%), which was ablated (maximum 22%) with L-NAME (100 mg/kg) and atropine (1 µM) pretreatment or endothelium removal. Gitogenin was found more potent against angiotensin II precontractions without effect on high K+ and low K+ precontractions. In isolated rat right atria, gitogenin suppressed rate and force of contractions. Atropine (1 µM) pretreatment partially inhibited effect of gitogenin on force and eliminated its effect on rate. Combined atropine (10 µM) and atenolol (0.5 µM) pretreatment was without effect on force of contractions but eliminated effect of gitogenin on rate with 25% increase.Conclusion: These findings indicate that antihypertensive effect of gitogenin is the outcome of vascular and cardiac effects; agonistic effect on vascular M3 and cardiac M2 receptors; and being more selective for M2. Increase in the rate of atrial contraction might be of clinical importance.

Evaluation of phytochemical, anti-oxidant and cardiac depressant effect of Rumex dentatus by using Langendorff's isolated heart apparatus.

Rumex dentatus has been used traditionally for ailment of cardiovascular diseases. The aim of the present study was to assess cardiovascular effects in isolated perfused rabbit heart. Aqueous and n-butanolic fractions were assessed for their effect on perfusion pressure (PP), force of contraction (FC) and heart rate (HR) of rabbit heart using Langendorff's method. The possible mechanisms of action of extracts/fraction were assessed with and without application of different agonist/antagonist. Phytochemical, toxicity and anti-oxidant activities were also determined. Both extracts at 1mg/mL dose produced a highly significant decrease in FC and HR but PP remained unchanged. Moreover, aqueous fraction of Rumex dentatus at 0.001mg/mL dose produced a highly significant decrease in FC and HR but no significant change in PP was observed. Atropine 10-5 M did not inhibit the cardiac depressant response of both fractions. Furthermore, both fractions blocked the positive ionotropic and chronotropic effects of adrenaline and calcium chloride. Phytochemical studies have shown the presence of some phytochemicals. Acute and sub-chronic toxicity studies demonstrated that test extracts are safe and produced no significant changes in haematological and biochemical parameters. Crude extract showed significant antioxidant activity like ascorbic acid. This study revealed that this plant have good cardiac depressant effect.

Cardiotonic potential of Carissa opaca Stapf ex Haines: A study on isolated rabbit heart.

Carissa opaca (C.O) is a wild shrub, belonging to the family Apocynaceae. The medicinal virtues of this plant have long been known. The present study demonstrates the effects of aqueous-methanolic extract and various fractions (n-butanolic and aqueous) of Carissa opaca on cardiovascular parameters. The perfusion pressure (PP), force of contraction (FC) and heart rate (HR) were assessed on isolated heart of rabbit using Langendroff's technique for crude extract and fractions of C.O, followed by the elucidation of the mechanism of action after estimating toxicity of the plant. Negative ionotropic and positive chronotropic effects, with an increase in PP in isolated perfused rabbit heart were observed the with plant extract and fractions. The aqueous-methanolic extract exhibited maximum response at 1mg/ml while the n-butanolic and aqueous fractions showed a maximum response at 1mg/ml and 10µg/ml respectively. Both fractions produced the same response when treated with atropine (10-5 M), however the actions of adrenaline (10-5 M) and calcium chloride (10-5 M) remained unblocked. Acute toxicity studies indicated that the plant was safe up to 2000 mg/kg and sub-chronic studies demonstrated that no significant change in haematological and biochemical parameters observed. In conclusion, this study supports the folkloric claim of C.O extract.

Mechanism underlying the vasodilation induced by diosmetin in porcine coronary artery.

Diosmetin is a flavonoid present naturally in citrus fruit. Plants containing diosmetin have been reported to have anti-hypertensive and vasorelaxant effects. Therefore, experiments were carried out to study the effects of diosmetin in segments of the porcine coronary artery (PCA). PCA rings were mounted for isometric tension recording in isolated tissue baths and pre-contracted with the thromboxane A2 mimetic U46619 or KCl. Cumulative concentration response curves to diosmetin were then carried out in the presence or absence of inhibitors or activators of different signaling pathways. The effect on calcium channels was determined by investigating the effect of a single concentration of diosmetin (30 µM) on calcium-induced contractions or contractions to BAY K8644. Diosmetin caused a concentration-dependent relaxation after pre-contraction with U46619 or KCl, which was unaffected by removal of the endothelium. Tetraethylammonium (TEA), and 4-aminopyridine (4-AP), but not barium chloride, caused significant inhibition of the diosmetin-mediated vasorelaxation, indicating a role for potassium channels. Diosmetin inhibited calcium-induced contractions and contractions to the L-type calcium channel opener BAY K8644. Furthermore, diosmetin inhibited the contractions in response to caffeine, cyclopiazonic acid and ionomycin, indicating a general effect on calcium-induced contractions. Contractions in response to the protein kinase C (PKC) activator Phorbol 12-myristate 13-acetate (PMA) were also inhibited by diosmetin, suggesting that it may inhibit a calcium-activated PKC isoform. In summary, diosmetin produced significant vasodilatory effects. The data indicate a role for potassium channels as well as an effect on calcium-induced contractile pathways, possible through inhibition of PKC.

Effect of varying quantities of polymer on preparation and stability evaluation of carbamazepine cocrystals with dicarboxylic acid coformers.

The current study is an attempt to explore the effect of varying quantities of hydroxypropyl cellulose (HPC) polymer on carbamazepine (CBZ) cocrystal formation with dicarboxylic acid coformers i.e., malonic acid (MA), succinic acid (SA), glutaric acid (GA), and adipic acid (AA). The cocrystals were first prepared without polymer by slurry crystallization method and then tried with different quantities of the polymer. The prepared samples were characterized by Powder X-ray Diffraction (XRPD). The characterization results indicate that in methanol pure carbamazepine-malonic (CBZ-MA) and carbamazepine-adipic acid (CBZ-AA) cocrystal can be prepared, while in ethanol and acetone pure carbamazepine-succinic (CBZ-SA) and carbamazepine-glutaric acid (CBZ-GA) cocrystals can be obtained respectively. The same cocrystals were tried using HPC polymer in three different quantities. The characterization results showed that a higher quantity of HPC polymer transforms CBZ-MA cocrystal polymorph-I to polymorph-II. The CBZ-SA and CBZ-GA cocrystal formation somehow inhibited as the concentration of HPC polymer increases. But on the other side, the formation of CBZ-AA cocrystal utterly not inhibited in the presence of varying quantities of HPC polymer. Furthermore, 11 different quantities of HPC were tried to know about the inhibitory concentration of HPC on CBZ-AA cocrystal formation. The CBZ-AA cocrystal preparation was not inhibited even at higher quantities of HPC compared to the coformer. Additionally, the effect of three different quantities of HPC on the thermal stability of the CBZ-AA cocrystal was investigated. Moreover, the stability of pure CBZ at 92% relative humidity (RH) condition was compared to CBZ-AA cocrystal with and without HPC polymer. The CBZ-AA cocrystal with and without HPC polymer was more stable than pure CBZ.