Effects of Local Vasodilators and the Autonomic Nervous System on Microcirculation and Mitochondrial Function in Septic Rats.

Systemic vasodilating agents like nitroglycerin (NG) or iloprost (Ilo) show beneficial effects on intestinal microcirculation during sepsis, which could be attenuated by activation of the sympathetic nervous system or systemic side effects of vasodilating agents. This exploratory study aimed to investigate the effects of topically administered vasodilators and the parasympathetic drug carbachol on colonic microcirculatory oxygenation (µHbO2), blood flow (µFlow) and mitochondrial respiration. A total of 120 male Wistar rats were randomly assigned to twelve groups and underwent either colon ascendens stent peritonitis (CASP) or sham surgery. After 24 h, animals received the following therapeutic regimes: (1) balanced full electrolyte solution, (2) carbachol, (3) NG, (4) Ilo, (5) NG + carbachol, and (6) Ilo + carbachol. Mitochondrial respiration was measured in colon homogenates by respirometry. In sham animals, NG (-13.1%*) and Ilo (-10.5%*) led to a decrease in µHbO2. Additional application of carbachol abolished this effect (NG + carbachol: -4.0%, non-significant; Ilo + carbachol: -1.4%, non-significant). In sepsis, carbachol reduced µHbO2 when applied alone (-10.5%*) or in combination with NG (-17.6%*). Thus, the direction and degree of this effect depend on the initial pathophysiologic condition.

Preparation and Vasodilation Mechanism of Angiotensin-I-Converting Enzyme Inhibitory Peptide from Ulva prolifera Protein.

Ulva prolifera, a type of green algae that can be consumed, was utilized in the production of an angiotensin-I converting enzyme (ACE) inhibitory peptide. The protein from the algae was isolated and subsequently hydrolyzed using a neutral protease. The resulting hydrolysate underwent several processes including Sephadex-G100 filtration chromatography, ultrafiltration, HPLC-Q-TOF-MS analysis, ADMET screening, UV spectrum detection test, molecular docking, and molecular dynamic simulation. Then, the ACE inhibitory peptide named KAF (IC50, 0.63 ± 0.26 µM) was identified. The effectiveness of this peptide in inhibiting ACE can be primarily attributed to two conventional hydrogen bonds. Additionally, it could activate endothelial nitric oxide synthase (eNOS) activity to promote the generation of nitric oxide (NO). Additionally, KAF primarily increased the intracellular calcium (Ca2+) level by acting on L-type Ca2+ channel (LTCC) and the ryanodine receptor (RyR) in the endoplasmic reticulum, and completed the activation of eNOS under the mediation of protein kinase B (Akt) signaling pathway. Our study has confirmed that KAF has the potential to be processed into pharmaceutical candidate functions on vasoconstriction.

Brain-wide mapping of c-Fos expression in nitroglycerin-induced models of migraine.

BACKGROUND: Migraine is a neurological disorder characterized by complex, widespread, and sudden attacks with an unclear pathogenesis, particularly in chronic migraine (CM). Specific brain regions, including the insula, amygdala, thalamus, and cingulate, medial prefrontal, and anterior cingulate cortex, are commonly activated by pain stimuli in patients with CM and animal models. This study employs fluorescence microscopy optical sectioning tomography (fMOST) technology and AAV-PHP.eB whole-brain expression to map activation patterns of brain regions in CM mice, thus enhancing the understanding of CM pathogenesis and suggesting potential treatment targets. METHODS: By repeatedly administering nitroglycerin (NTG) to induce migraine-like pain in mice, a chronic migraine model (CMM) was established. Olcegepant (OLC) was then used as treatment and its effects on mechanical pain hypersensitivity and brain region activation were observed. All mice underwent mechanical withdrawal threshold, light-aversive, and elevated plus maze tests. Viral injections were administered to the mice one month prior to modelling, and brain samples were collected 2 h after the final NTG/vehicle control injection for whole-brain imaging using fMOST. RESULTS: In the NTG-induced CMM, mechanical pain threshold decreased, photophobia, and anxiety-like behavior were observed, and OLC was found to improve these manifestations. fMOST whole-brain imaging results suggest that the isocortex-cerebral cortex plate region, including somatomotor areas (MO), somatosensory areas (SS), and main olfactory bulb (MOB), appears to be the most sensitive area of activation in CM (P < 0.05). Other brain regions such as the inferior colliculus (IC) and intermediate reticular nucleus (IRN) were also exhibited significant activation (P < 0.05). The improvement in migraine-like symptoms observed with OLC treatment may be related to its effects on these brain regions, particularly SS, MO, ansiform lobule (AN), IC, spinal nucleus of the trigeminal, caudal part (Sp5c), IRN, and parvicellular reticular nucleus (PARN) (P < 0.05). CONCLUSIONS: fMOST whole-brain imaging reveals c-Fos + cells in numerous brain regions. OLC improves migraine-like symptoms by modulating brain activity in some brain regions. This study demonstrates the activation of the specific brain areas in NTG-induced CMM and suggests some regions as a potential treatment mechanism according to OLC.

Relationship between peripheral and intracoronary blood flow in patients with angina and nonobstructive coronary arteries.

Coronary vasomotor dysfunction, an important underlying cause of angina and nonobstructive coronary arteries (ANOCA), encompassing coronary vasospasm, coronary endothelial dysfunction, and/or coronary microvascular dysfunction, is clinically assessed by invasive coronary function testing (ICFT). As ICFT imposes a high burden on patients and carries risks, developing noninvasive alternatives is important. We evaluated whether coronary vasomotor dysfunction is a component of systemic microvascular endothelial and smooth muscle dysfunction and can be detected using laser speckle contrast analysis (LASCA). Forty-three consecutive patients with ANOCA underwent ICFT, with intracoronary acetylcholine, adenosine, and flow measurements, to assess coronary vasomotor dysfunction. Cutaneous microvascular function was assessed using LASCA in the forearm, combined with vasodilators acetylcholine, sodium nitroprusside, and insulin and using EndoPAT, by measuring the reactive hyperemia index (RHI). Of the 43 included patients with ANOCA (79% women, 59 ± 9 yr old), 38 patients had coronary vasomotor dysfunction, including 28 with coronary vasospasm, 26 with coronary endothelial dysfunction, and 18 with coronary microvascular dysfunction, with overlapping endotypes. Patients with and without coronary vasomotor dysfunction had similar peripheral flow responses to acetylcholine, insulin, and RHI. In contrast, coronary vasomotor dysfunction was associated with lower peripheral flow responses to sodium nitroprusside (P < 0.001). An absolute flow response to sodium nitroprusside of 83.95 APU resulted in 86.1% sensitivity and 80.0% specificity for coronary vasomotor dysfunction (area under the ROC curve, 0.883; P = 0.006). In conclusion, this study provides evidence of systemic vascular smooth muscle dysfunction in patients with ANOCA with coronary vasomotor dysfunction and the diagnostic value of peripheral microvascular function testing as a noninvasive tool for detecting coronary vasomotor dysfunction.NEW & NOTEWORTHY This study provides proof of concept that assessment of the peripheral vasculature, particularly vascular smooth muscle cells measured using the LASCA technology holds potential as a noninvasive tool for detecting coronary vasomotor dysfunction. This finding highlights the potential of the LASCA technology in, for example, medication studies for coronary vasomotor dysfunction, especially when investigating whether medication improves vascular function, as repeated peripheral measurements are less invasive than invasive coronary function testing, the current gold standard.

An overview of pyridazin-3(2H)-one: a core for developing bioactive agents targeting cardiovascular diseases and cancer.

Cardiovascular diseases (CVDs) and cancer are the top two leading causes of death globally. Vasodilators are commonly used to treat various CVDs. In cancer treatment, targeted anticancer agents have been developed to minimize side effects compared with traditional chemotherapy. Many hypertension patients are more prone to cancer, a case known as reverse cardio-oncology. This leads to the search for drugs with dual activity or repurposing strategy to discover new therapeutic uses for known drugs. Recently, medicinal chemists have shown great interest in synthesizing pyridazinone derivatives due to their significant biological activities in tackling these critical health challenges. This review will concentrate on pyridazin-3(2H)-one-containing compounds as vasodilators and anticancer agents, along with a brief overview of various methods for their synthesis.

[Box: see text].

Basal release and relaxation responses to 6-nitrodopamine in swine carotid, coronary, femoral, and renal arteries.

Mammalian and reptilian vascular tissues present basal release of 6-nitrodopamine, which is reduced when the tissues are pre-incubated with the NO synthase inhibitor L-NG-Nitro arginine methyl ester (L-NAME), or when the endothelium is mechanically removed. 6-Nitrodopamine induces vasorelaxation in pre-contracted vascular rings by antagonizing the dopaminergic D2-like receptor. Here it was investigated whether male swine vessels (including carotid, left descendent coronary, renal, and femoral arteries) release 6-nitrodopamine, dopamine, noradrenaline, and adrenaline, as measured by liquid chromatography coupled to tandem mass spectrometry. The in vitro vasorelaxant action of 6-nitrodopamine was evaluated in carotid, coronary, renal, and femoral arteries precontracted by U-46619 (3 nM), and compared to that induced by the dopamine D2-receptor antagonist L-741,626. Expression of tyrosine hydroxylase and the neuromaker calretinin was investigated by immunohistochemistry. All vascular tissues presented basal release of endothelium-derived catecholamines. The relaxation induced by 6-nitrodopamine was not affected by preincubation of the tissues with either L-NAME (100 µM, 30-min preincubation) or the heme-site inhibitor of soluble guanylyl cyclase ODQ (100 µM, 30-min preincubation). Electrical field stimulation (EFS)-induced contractions were significantly potentiated by previous incubation with L-NAME, but unaffected by ODQ preincubation. The contractions induced by EFS were reduced by preincubation with either 6-nitrodopamine or L-741,626. Immunohistochemistry in all arteries revealed the presence of tyrosine hydroxylase in the endothelium, whereas immunoreactivity for calretinin was negative. Swine vessels present basal release of endothelium-derived catecholamines and expression of tyrosine hydroxylase in the endothelium. The vasodilation induced by 6-nitrodopamine is due to blockade of dopaminergic D2-like receptors.

A Comparative Investigation of the Pulmonary Vasodilating Effects of Inhaled NO Gas Therapy and Inhalation of a New Drug Formulation Containing a NO Donor Metabolite (SIN-1A).

Numerous research projects focused on the management of acute pulmonary hypertension as Coronavirus Disease 2019 (COVID-19) might lead to hypoxia-induced pulmonary vasoconstriction related to acute respiratory distress syndrome. For that reason, inhalative therapeutic options have been the subject of several clinical trials. In this experimental study, we aimed to examine the hemodynamic impact of the inhalation of the SIN-1A formulation (N-nitroso-N-morpholino-amino-acetonitrile, the unstable active metabolite of molsidomine, stabilized by a cyclodextrin derivative) in a porcine model of acute pulmonary hypertension. Landrace pigs were divided into the following experimental groups: iNO (inhaled nitric oxide, n = 3), SIN-1A-5 (5 mg, n = 3), and SIN-1A-10 (10 mg, n = 3). Parallel insertion of a PiCCO system and a pulmonary artery catheter (Swan-Ganz) was performed for continuous hemodynamic monitoring. The impact of iNO (15 min) and SIN-1A inhalation (30 min) was investigated under physiologic conditions and U46619-induced acute pulmonary hypertension. Mean pulmonary arterial pressure (PAP) was reduced transiently by both substances. SIN-1A-10 had a comparable impact compared to iNO after U46619-induced pulmonary hypertension. PAP and PVR decreased significantly (changes in PAP: -30.1% iNO, -22.1% SIN-1A-5, -31.2% SIN-1A-10). While iNO therapy did not alter the mean arterial pressure (MAP) and systemic vascular resistance (SVR), SIN-1A administration resulted in decreased MAP and SVR values. Consequently, the PVR/SVR ratio was markedly reduced in the iNO group, while SIN-1A did not alter this parameter. The pulmonary vasodilatory impact of inhaled SIN-1A was shown to be dose-dependent. A larger dose of SIN-1A (10 mg) resulted in decreased PAP and PVR in a similar manner to the gold standard iNO therapy. Inhalation of the nebulized solution of the new SIN-1A formulation (stabilized by a cyclodextrin derivative) might be a valuable, effective option where iNO therapy is not available due to dosing difficulties or availability.

Coronary and Systemic Vasodilator Responsiveness of Patients Receiving Conventional Intermittent or Nocturnal Hemodialysis.

BACKGROUND: Nocturnal hemodialysis (nHD) restores the attenuated brachial artery vasodilator responsiveness of patients receiving conventional intermittent hemodialysis (iHD). Its impact on coronary vasodilatation is unknown. METHODS: We evaluated 25 patients on hemodialysis who fulfilled transplant criteria: 15 on iHD (4-hour sessions, 3 d/wk) and 10 on nHD (≈40 h/wk over 8-10-hour sessions) plus 6 control participants. Following diagnostic angiography, left anterior descending (LAD) coronary flow reserve and mean luminal diameter were quantified at baseline and during sequential intracoronary administration of adenosine (infusion and bolus), nitroglycerin (bolus), acetylcholine (infusion), acetylcholine coinfused with vitamin C, and, finally, sublingual nitroglycerin. RESULTS: Coronary flow reserve in those receiving nHD was augmented relative to iHD (3.28±0.26 versus 2.17±0.12 [mean±SEM]; P<0.03) but attenuated, relative to controls (4.80±0.63; P=0.011). Luminal dilatations induced by intracoronary adenosine and nitroglycerin were similar in nHD and controls but blunted in the iHD cohort (P<0.05 versus both). ACh elicited vasodilatation in controls but constriction in both dialysis groups (both P<0.05, versus control); vitamin C coinfusion had no effect. Sublingual nitroglycerin increased mid-left anterior descending diameter and reduced mean arterial pressure in controls (+15.2±2.68%; -16.00±1.60%) and in nHD recipients (+14.78±5.46%; -15.82±1.32%); iHD responses were markedly attenuated (+1.9±0.86%; -5.89±1.41%; P<0.05, all comparisons). CONCLUSIONS: Coronary and systemic vasodilator responsiveness to both adenosine and nitroglycerin is augmented in patients receiving nHD relative to those receiving iHD, whereas vasoconstrictor responsiveness to acetylcholine does not differ. By improving coronary conduit and microvascular function, nHD may reduce the cardiovascular risk of patients on dialysis.

Preventing Sheep Carotid Artery Spasm for Vascular Graft Surgery and Computed Tomography Angiography.

The development of small-diameter vascular grafts requires testing in large animal models before advancing to clinical trials. Vascular graft interposition implantation in sheep carotid arteries (CAs) is the most widely used model, but ovine CAs are prone to severe spasm following surgical manipulation, potentially impairing graft performance assessment. There is paucity in the literature on reducing sheep CA spasm using effective vasodilator therapeutic protocols. In this study, four healthy Merino cross White Suffolk wethers (1-2 years, 52.1 ± 0.8 kg) underwent CT angiography and CA graft surgery. CT angiography using iodinated contrast agent was performed with innominate artery access through the CA or ascending aortic arch access through the femoral artery. Sheep then underwent right CA sham surgery or left CA vascular graft implantation. A variety of vasodilators, including papaverine, sodium nitroprusside, verapamil, and their combination, were tested for preventing or treating CA spasms intraoperatively. Blood flow was reassessed immediately after CA surgery using CT angiography. The results showed that innominate artery access through the CA for CT angiography in sheep induced presurgical CA spasm with reduced arterial flow. Conversely, ascending aortic arch access through the femoral artery for CT angiography did not cause CA spasm and maintained arterial flow. During CA graft surgery, surgical trauma induced CA spasm, which was prevented by localized intra-arterial administration of vasodilators papaverine hydrochloride and verapamil before significant surgical manipulation.

Vasoactive and Antifibrotic Properties of Cannabinoids and Applications to Vasospastic/Vaso-Occlusive Disorders: A Systematic Review.

BACKGROUND: Management of vasospastic and vaso-occlusive disorders is a complex challenge, with current treatments showing varied success. Cannabinoids have demonstrated both vasodilatory and antifibrotic properties, which present potential mechanisms for therapeutic relief. No existing review examines these effects in peripheral circulation in relation to vasospastic and vaso-occlusive disorders. This study aims to investigate vasodilatory and antifibrotic properties of cannabinoids in peripheral vasculature for application in vasospastic and vaso-occlusive disorders affecting the hand. METHODS: A systematic search was conducted by 2 independent reviewers across PubMed, Cochrane, Ovid MEDLINE, and CINAHL to identify studies in accordance with the determined inclusion/exclusion criteria. Information regarding study design, medication, dosage, and hemodynamic or antifibrotic effects were extracted. Descriptive statistics were used to summarize study findings as appropriate. RESULTS: A total of 584 articles were identified, and 32 were selected for inclusion. Studies were grouped by effect type: hemodynamic (n = 17, 53%) and antifibrotic (n = 15, 47%). Vasodilatory effects including reduced perfusion pressure, increased functional capillary density, inhibition of vessel contraction, and increased blood flow were reported in 82% of studies. Antifibrotic effects including reduced dermal thickening, reduced collagen synthesis, and reduced fibroblast migration were reported in 100% of studies. CONCLUSION: Overall, cannabinoids were found to have vasodilatory and antifibrotic effects on peripheral circulation via both endothelium-dependent and independent mechanisms. Our review suggests the applicability of cannabis-based medicines for vasospastic and vaso-occlusive disorders affecting the hand (eg, Raynaud disease, Buerger disease). Future research should aim to assess the effectiveness of cannabis-based medicines for these conditions.

Genistein mitigates nitroglycerine-induced migraine: modulation of nitric oxide-mediated vasodilation and oxidative stress.

Migraine is a widespread brain condition described by frequent, recurrent episodes of incapacitating, moderate-to-severe headaches with throbbing pain that are usually one-sided. It is the 2nd most debilitating state lived with disability in terms of years, with a prevalence rate of 15-20%. Significant drops in estrogen levels have been associated with triggering acute migraine attacks in certain cases. Phytoestrogens are plant-derived compounds that resemble estrogen in structure, enabling them to imitate estrogen's functions in the body by attaching to estrogen receptors. Thus, the study was aimed to explore the protective effect of genistein against migraine. Moreover, the role of nitric oxide was also studied in the observed effect of genistein. Nitric oxide (NO) is implicated in migraine pathophysiology due to its role in promoting cerebral vasodilation and modulation of pain perception. Exploring L-NAME, a nitric oxide synthase inhibitor in migraine research helps scientists better understand the role of NO in migraine. Nitroglycerine treatment significantly increased the facial-unilateral head pain and spontaneous pain, as evidenced by the increased number of head scratching and groomings. Nitroglycerine treatment also induced anxiogenic behavior in mice. A significant reduction in the number of entries in the light phase and open arm, respectively. Biochemical analysis indicated a significant increase in inflammatory and oxidative stress in the nitroglycerin group. A significant increase and decrease in brain TBARS and GSH were observed with nitroglycerine treatment, respectively. Moreover, nitroglycerine treatment has uplifted the serum TNF-α level. Genistein (20 mg/kg) significantly mitigated the facial-unilateral head pain, spontaneous pain, photophobia, and anxiety-like behavior induced by nitroglycerine. Biochemical analysis showed that genistein (20 mg/kg) significantly abrogated the nitroglycerine-induced lipid peroxidation and increased serum TNF-α level. Genistein treatment also upregulated the brain GSH level and downregulated the serum TNF-α level. The L-NAME-mediated alleviation of the protective effect of genistein might be attributed to the vasodilatory effect of L-NAME. Conclusively, it can be suggested that genistein might provide relief from migraine pain by inhibiting nitric oxide-mediated vasodilation and oxidative stress.

Intracellular pathways of calcitonin gene-related peptide-induced relaxation of human coronary arteries: A key role for Gßγ subunit instead of cAMP.

BACKGROUND AND PURPOSE: Calcitonin gene-related peptide (CGRP) is a potent vasodilator. While its signalling is assumed to be mediated via increases in cAMP, this study focused on elucidating the actual intracellular signalling pathways involved in CGRP-induced relaxation of human isolated coronary arteries (HCA). EXPERIMENTAL APPROACH: HCA were obtained from heart valve donors (27 M, 25 F, age 54 ± 2 years). Concentration-response curves to human α-CGRP or forskolin were constructed in HCA segments, incubated with different inhibitors of intracellular signalling pathways, and intracellular cAMP levels were measured with and without stimulation. RESULTS: Adenylyl cyclase (AC) inhibitors SQ22536 + DDA and MDL-12330A, and PKA inhibitors Rp-8-Br-cAMPs and H89, did not inhibit CGRP-induced relaxation of HCA, nor did the guanylyl cyclase inhibitor ODQ, PKG inhibitor KT5823, EPAC1/2 inhibitor ESI09, potassium channel blockers TRAM-34 + apamin, iberiotoxin or glibenclamide, or the Gαq inhibitor YM-254890. Phosphodiesterase inhibitors induced a concentration-dependent decrease in the response to KCl but did not potentiate relaxation to CGRP. Relaxation to forskolin was not blocked by PKA or AC inhibitors, although AC inhibitors significantly inhibited the increase in cAMP. Inhibition of Gßγ subunits using gallein significantly inhibited the relaxation to CGRP in human coronary arteries. CONCLUSION: While CGRP signalling is generally assumed to act via cAMP, the CGRP-induced vasodilation in HCA was not inhibited by targeting this intracellular signalling pathway at different levels. Instead, inhibition of Gßγ subunits did inhibit the relaxation to CGRP, suggesting a different mechanism of CGRP-induced relaxation than generally believed.

Vasorelaxant and Blood Pressure-Lowering Effects of Cnidium monnieri Fruit Ethanol Extract in Sprague Dawley and Spontaneously Hypertensive Rats.

Cnidium monnieri (L.) Cusson, a member of the Apiaceae family, is rich in coumarins, such as imperatorin and osthole. Cnidium monnieri fruit (CM) has a broad range of therapeutic potential that can be used in anti-bacterial, anti-cancer, and sexual dysfunction treatments. However, its efficacy in lowering blood pressure through vasodilation remains unknown. This study aimed to assess the potential therapeutic effect of CM 50% ethanol extract (CME) on hypertension and the mechanism of its vasorelaxant effect. CME (1-30 µg/mL) showed a concentration-dependent vasorelaxation on constricted aortic rings in Sprague Dawley rats induced by phenylephrine via an endothelium-independent mechanism. The vasorelaxant effect of CME was inhibited by blockers of voltage-dependent and Ca2+-activated K+ channels. Additionally, CME inhibited the vascular contraction induced by angiotensin II and CaCl2. The main active compounds of CM, i.e., imperatorin (3-300 µM) and osthole (1-100 µM), showed a concentration-dependent vasorelaxation effect, with half-maximal effective concentration values of 9.14 ± 0.06 and 5.98 ± 0.06 µM, respectively. Orally administered CME significantly reduced the blood pressure of spontaneously hypertensive rats. Our research shows that CME is a promising treatment option for hypertension. However, further studies are required to fully elucidate its therapeutic potential.

A mathematical model for temporal cerebral blood flow response to acetazolamide evaluated in patients with Moyamoya disease.

BACKGROUND: Paired cerebral blood flow (CBF) measurement is usually acquired before and after vasoactive stimulus to estimate cerebrovascular reserve (CVR). However, CVR may be confounded because of variations in time-to-maximum CBF response (tmax) following acetazolamide injection. With a mathematical model, CVR can be calculated insensitive to variations in tmax, and a model offers the possibility to calculate additional model-derived parameters. A model that describes the temporal CBF response following a vasodilating acetazolamide injection is proposed and evaluated. METHODS: A bi-exponential model was adopted and fitted to four CBF measurements acquired using arterial spin labelling before and initialised at 5, 15 and 25 min after acetazolamide injection in a total of fifteen patients with Moyamoya disease. Curve fitting was performed using a non-linear least squares method with a priori constraints based on simulations. RESULTS: Goodness of fit (mean absolute error) varied between 0.30 and 0.62 ml·100 g-1·min-1. Model-derived CVR was significantly higher compared to static CVR measures. Maximum CBF increase occurred earlier in healthy- compared to diseased vascular regions. CONCLUSIONS: The proposed mathematical model offers the possibility to calculate CVR insensitive to variations in time to maximum CBF response which gives a more detailed characterisation of CVR compared to static CVR measures. Although the mathematical model adapts generally well to this dataset of patients with MMD it should be considered as experimental; hence, further studies in healthy populations and other patient cohorts are warranted.

The antidiabetic drug ipragliflozin induces vasorelaxation of rabbit femoral artery by activating a Kv channel, the SERCA pump, and the PKA signaling pathway.

We explored the vasorelaxant effects of ipragliflozin, a sodium-glucose cotransporter-2 inhibitor, on rabbit femoral arterial rings. Ipragliflozin relaxed phenylephrine-induced pre-contracted rings in a dose-dependent manner. Pre-treatment with the ATP-sensitive K+ channel inhibitor glibenclamide (10 µM), the inwardly rectifying K+ channel inhibitor Ba2+ (50 µM), or the Ca2+-sensitive K+ channel inhibitor paxilline (10 µM) did not influence the vasorelaxant effect. However, the voltage-dependent K+ (Kv) channel inhibitor 4-aminopyridine (3 mM) reduced the vasorelaxant effect. Specifically, the vasorelaxant response to ipragliflozin was significantly attenuated by pretreatment with the Kv7.X channel inhibitors linopirdine (10 µM) and XE991 (10 µM), the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) pump inhibitors thapsigargin (1 µM) and cyclopiazonic acid (10 µM), and the cAMP/protein kinase A (PKA)-associated signaling pathway inhibitors SQ22536 (50 µM) and KT5720 (1 µM). Neither the cGMP/protein kinase G (PKG)-associated signaling pathway nor the endothelium was involved in ipragliflozin-induced vasorelaxation. We conclude that ipragliflozin induced vasorelaxation of rabbit femoral arteries by activating Kv channels (principally the Kv7.X channel), the SERCA pump, and the cAMP/PKA-associated signaling pathway independent of other K+ (ATP-sensitive K+, inwardly rectifying K+, and Ca2+-sensitive K+) channels, cGMP/PKG-associated signaling, and the endothelium.

Influence of trimetazidine on myocardial injury in mice with diabetic cardiomyopathy.

INTRODUCTION: The prevalence of diabetes mellitus is increasing year by year globally, and diabetic cardiomyopathy (DCM), as the most common complication of type 2 diabetes mellitus, seriously affects the prognosis of patients. Trimetazidine (TMZ), as a drug affecting myocardial energy metabolism, mainly reduces the oxidation rate of ß-oxidation by inhibiting 3-ketoacyl-CoA thiolase (3-KAT), a key enzyme in ß-oxidation of free fatty acid (FFA), so that the energy metabolism substrate of cardiomyocytes preferentially selects glucose rather than fatty acids, increases the content of intracellular adenosine triphosphate (ATP), enhances the contractile function of cardiomyocytes, and improves the state of cellular ischemia and hypoxia. Previous studies have shown that TMZ is closely related to the activation and induction of apoptosis of the MAPK pathway and AMPK pathway, and plays a role in the treatment of diabetic cardiomyopathy, but the specific mechanism is still unclear. OBJECTIVE: This study aims to investigate the impact of TMZ on myocardial damage in mice exhibiting diabetic cardiomyopathy (DCM), and to furnish a laboratory foundation for the clinical treatment of diabetic cardiomyopathy. METHOD: Male db/db mice (6 weeks old, n = 21) and male wild-type (wt) (6 weeks old, n = 20) mice were selected for the study. The wt mice were randomly assigned to the wt group (n = 10) and wt + TMZ group (n = 10), while the remaining db/db mice were randomly allocated to the db/db group (n = 11) and db/db + TMZ group (n = 10). Following 8 weeks of feeding, the wt + TMZ group and db/db + TMZ group received TMZ via gavage, whereas the remaining groups were administered physiological saline. Periodic measurements of blood glucose, blood lipids, and myocardial enzymes were conducted in mice, with samples obtained after the 12th week for subsequent biochemical analysis, myocardial pathology assessment, immunohistochemistry, western blot analysis, and TUNEL staining (TdT-mediated dUTP Nick-End Labeling). RESULT: GLU, TC, TG, LDL-C, and CK-MB levels were significantly higher in db/db mice compared to wt mice (GLU: M ± SD wt 5.94 ± 0.37, db/db 17.63 ± 0.89, p < 0.05, ES = 0.991; TC: M ± SD wt 3.01 ± 0.32, db/db 6.97 ± 0.36, p < 0.05, ES = 0.972; TG: M ± SD wt 0.58 ± 0.2, db/db 1.75 ± 0.14, p < 0.05, ES = 0.920; LDL-C: M ± SD wt 1.59 ± 0.12, db/db 3.87 ± 0.14, p < 0.05, ES = 0.989; CK-MB: M ± SD wt 0.12 ± 0.01, db/db 0.31 ± 0.04, p < 0.05, ES = 0.928). HDL-C levels were significantly lower in db/db mice (M ± SD wt 1.89 ± 0.08, db/db 0.64 ± 0.09, p < 0.05, ES = 0.963). Histopathological analysis confirmed myocardial damage in db/db mice. Treatment with TMZ reduced GLU, TC, TG, LDL-C, and CK-MB levels (p < 0.05, ES > 0.9) and increased HDL-C levels compared to untreated db/db mice. Additionally, TMZ treatment significantly decreased myocardial cell apoptosis (p < 0.05, ES = 0.980). These results demonstrate the efficacy of TMZ in reversing myocardial injury in DCM mice. CONCLUSION: TMZ can mitigate myocardial damage in db/db mice by downregulating the expression of caspase-12, a protein associated with the endoplasmic reticulum stress (ERS) cell apoptosis pathway, consequently diminishing cell apoptosis. This underscores the protective efficacy of TMZ against myocardial damage in mice afflicted with DCM.

Human recombinant relaxin-2 (serelaxin) regulates the proteome, lipidome, lipid metabolism and inflammatory profile of rat visceral adipose tissue.

Recombinant human relaxin-2 (serelaxin) has been widely proven as a novel drug with myriad effects at different cardiovascular levels, which support its potential therapeutic efficacy in several cardiovascular diseases (CVD). Considering these effects, together with the influence of relaxin-2 on adipocyte physiology and adipokine secretion, and the connection between visceral adipose tissue (VAT) dysfunction and the development of CVD, we could hypothesize that relaxin-2 may regulate VAT metabolism. Our objective was to evaluate the impact of a 2-week serelaxin treatment on the proteome and lipidome of VAT from Sprague-Dawley rats. We found that serelaxin increased 1 polyunsaturated fatty acid and 6 lysophosphatidylcholines and decreased 4 triglycerides in VAT employing ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) based platforms, and that regulates 47 phosphoproteins using SWATH/MS analysis. Through RT-PCR, we found that serelaxin treatment also caused an effect on VAT lipolysis through an increase in the mRNA expression of hormone-sensitive lipase (HSL) and a decrease in the expression of adipose triglyceride lipase (ATGL), together with a reduction in the VAT expression of the fatty acid transporter cluster of differentiation 36 (Cd36). Serelaxin also caused an anti-inflammatory effect in VAT by the decrease in the mRNA expression of tumor necrosis factor α (TNFα), interleukin-1ß (IL-1ß), chemerin, and its receptor. In conclusion, our results highlight the regulatory role of serelaxin in the VAT proteome and lipidome, lipolytic function, and inflammatory profile, suggesting the implication of several mechanisms supporting the potential benefit of serelaxin for the prevention of obesity and metabolic disorders.

The role of T-type calcium channels in elderly human vascular function: A pilot randomized controlled trial.

Endothelial dysfunction develops with age and may precede cardiovascular disease. Animal data suggest that T-type calcium channels play an important role in endothelial function, but data from humans are lacking. This study included 15 healthy, sedentary, elderly males for a double blinded, randomized controlled trial. For 8 weeks, they were given 40 mg/day of either efonidipine (L- and T-type calcium channel blocker (CCB)) or nifedipine (L-type CCB). Vascular function was evaluated by graded femoral arterial infusions of acetylcholine (ACh; endothelium-dependent vasodilator) and sodium nitroprusside (endothelium-independent vasodilator) both with and without co-infusion of N-acetylcysteine (NAC; antioxidant). We measured leg blood flow and mean arterial pressure and calculated leg vascular conductance to evaluate the leg vascular responses. Despite no significant change in blood pressure in either group, we observed higher leg blood flow responses (Δ 0.43 ± 0.45 l/min, P = 0.006) and leg vascular conductance (Δ 5.38 ± 5.67 ml/min/mmHg, P = 0.005) to intra-arterial ACh after efonidipine, whereas there was no change in the nifedipine group, and no differences between groups. We found no upregulation of endothelial nitric oxide synthase in vastus lateralis muscle biopsies within or between groups. Smooth muscle cell responsiveness was unaltered by efonidipine or nifedipine. Intravenous co-infusion of NAC did not affect endothelium-dependent vasodilatation in either of the CCB groups. These results suggest that 8 weeks' inhibition of T- and L-type calcium channels augments endothelium-dependent vasodilatory function in healthy elderly males. Further studies are required to elucidate if T-type calcium channel inhibition can counteract endothelial dysfunction.

Structural Characterization and Rat Aortic Vascular Reactivity of Bradykinin-Potentiating Peptides (BPPs) from the Snake Venom of Bothrops moojeni from Delta do Parnaíba Region, Brazil.

Snake venoms contain various bradykinin-potentiating peptides (BPPs). First studied for their vasorelaxant properties due to angiotensin converting enzyme (ACE) inhibition, these molecules present a range of binding partners, among them the argininosuccinate synthase (AsS) enzyme. This has renewed interest in their characterization from biological sources and the evaluation of their pharmacological activities. In the present work, the low molecular weight fraction of Bothrops moojeni venom was obtained and BPPs were characterized by mass spectrometry. Eleven BPPs or related peptides were sequenced, and one of them, BPP-Bm01, was new. Interestingly, some oxidized BPPs were detected. The three most abundant peptides were BPP-Bm01, BPP-Bax12, and BPP-13a, and their putative interactions with the AsS enzyme were investigated in silico. A binding cavity for these molecules was predicted, and docking studies allowed their ranking. Three peptides were synthesized and submitted to vasorelaxation assays using rat aortic rings. While all BPPs were active, BPP-Bm01 showed the highest potency in this assay. This work adds further diversity to BPPs from snake venoms and suggests, for the first time, a putative binding pocket for these molecules in the AsS enzyme. This can guide the design of new and more potent AsS activators.

Absorbed Bioactive Compounds Replicate Guanxin II-Induced Endothelium-Associated in/ex vivo Vasodilation.

OBJECTIVE: To develop an interference-free and rapid method to elucidate Guanxin II (GX II)'s representative vasodilator absorbed bioactive compounds (ABCs) among enormous phytochemicals. METHODS: The contents of ferulic acid, tanshinol, and hydroxysafflor yellow A (FTA) in GX II/rat serum after the oral administration of GX II (30 g/kg) were detected using ultra-performance liquid chromatography-mass spectrometry. Totally 18 rats were randomly assigned to the control group (0.9% normal saline), GX II (30 g/kg) and FTA (5, 28 and 77 mg/kg) by random number table method. Diastolic coronary flow velocity-time integral (VTI), i.e., coronary flow or coronary flow-mediated dilation (CFMD), and endothelium-intact vascular tension of isolated aortic rings were measured. After 12 h of exposure to blank medium or 0.5 mmol/L H2O2, endothelial cells (ECs) were treated with post-dose GX II of supernatant from deproteinized serum (PGSDS, 300 µL PGSDS per 1 mL of culture medium) or FTA (237, 1539, and 1510 mg/mL) for 10 min as control, H2O2, PGSDS and FTA groups. Nitric oxide (NO), vascular endothelial growth factor (VEGF), endothelin-1 (ET-1), superoxide dismutase (SOD), malondialdehyde (MDA) and phosphorylated phosphoinositide 3 kinase (p-PI3K), phosphorylated protein kinase B (p-AKT), phosphorylated endothelial nitric oxide synthase (p-eNOS) were analyzed. PGSDS was developed as a GX II proxy of ex vivo herbal crude extracts. RESULTS: PGSDS effectively eliminates false responses caused by crude GX II preparations. When doses equaled the contents in GX II/its post-dose serum, FTA accounted for 98.17% of GX II -added CFMD and 92.99% of PGSDS-reduced vascular tension. In ECs, FTA/PGSDS was found to have significant antioxidant (lower MDA and higher SOD, P<0.01) and endothelial function-protective (lower VEGF, ET-1, P<0.01) effects. The increases in aortic relaxation, endothelial NO levels and phosphorylated PI3K/Akt/eNOS protein induced by FTA/PGSDS were markedly abolished by NG-nitro-L-arginine methyl ester (L-NA, eNOS inhibitor) and wortmannin (PI3K/AKT inhibitor), respectively, indicating an endothelium-dependent vasodilation via the PI3K/AKT-eNOS pathway (P<0.01). CONCLUSION: This study provides a strategy for rapidly and precisely elucidating GX II's representative in/ex vivo cardioprotective absorbed bioactive compounds (ABCs)-FTA, suggesting its potential in advancing precision ethnomedicine.