Changes in arterial myocyte excitability induced by subarachnoid hemorrhage in a rat model.

Aneurismal subarachnoid hemorrhage (aSAH) is a neurovascular disease produced by the rupture of the cerebral arteries and the extravasation of blood to the subarachnoid space and is accompanied by severe comorbidities. Secondarily associated vasospasm is one of the main side effects after hydrocephalus and possible rebleeding. Here, we analyze the alterations in function in the arteries of a rat model of SAH. For this, autologous blood was injected into the cisterna magna. We performed electrophysiological, microfluorimetric, and molecular biology experiments at different times after SAH to determine the functional and molecular changes induced by the hemorrhage. Our results confirmed that in SAH animals, arterial myocytes were depolarized on days 5 and 7, had higher [Ca2+]i on baseline, peaks and plateaus, and were more excitable at low levels of depolarization on day 7, than in the control and sham animals. Microarray analysis showed that, on day 7, the sets of genes related to voltage-dependent Ca2+ channels and K+ dynamics in SAH animals decreased, while the voltage-independent Ca2+ dynamics genes were over-represented. In conclusion, after SAH, several mechanisms involved in arterial reactivity were altered in our animal model, suggesting that there is no unique cause of vasospasm and alterations in several signaling pathways are involved in its development.

Changes in Adhesion and the Expression of Adhesion Molecules in PBMCs after Aneurysmal Subarachnoid Hemorrhage: Relation to Cerebral Vasospasm.

Aneurysmal subarachnoid hemorrhage (aSAH) is a neurovascular disease produced by extravasation of blood to the subarachnoid space after rupture of the cerebral vessels. After bleeding, the immune response is activated. The role of peripheral blood mononuclear cells (PBMCs) in this response is a current subject of research. We have analysed the changes in PBMCs of patients with aSAH and their interaction with the endothelium, focusing on their adhesion and the expression of adhesion molecules. Using an in vitro adhesion assay, we observed that the adhesion of PBMCs of patients with aSAH is increased. Flow cytometry analysis shows that monocytes increased significantly in patients, especially in those who developed vasospasm (VSP). In aSAH patients, the expression of CD162, CD49d, CD62L and CD11a in T lymphocytes and of CD62L in monocytes increased. However, the expression of CD162, CD43, and CD11a decreased in monocytes. Furthermore, monocytes from patients who developed arteriographic VSP had lower expression of CD62L. In conclusion, our results confirm that after aSAH, monocyte count and adhesion of PBMCs increase, especially in patients with VSP, and that the expression of several adhesion molecules is altered. These observations can help predict VSP and to improve the treatment of this pathology.

HDL anti-inflammatory function is impaired and associated with high SAA1 and low APOA4 levels in aneurysmal subarachnoid hemorrhage.

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating disease with high morbidity and mortality rates. Within 24 hours after aSAH, monocytes are recruited and enter the subarachnoid space, where they mature into macrophages, increasing the inflammatory response and contributing, along with other factors, to delayed neurological dysfunction and poor outcomes. High-density lipoproteins (HDL) are lipid-protein complexes that exert anti-inflammatory effects but under pathological conditions undergo structural alterations that have been associated with loss of functionality. Plasma HDL were isolated from patients with aSAH and analyzed for their anti-inflammatory activity and protein composition. HDL isolated from patients lost the ability to prevent VCAM-1 expression in endothelial cells (HUVEC) and subsequent adhesion of THP-1 monocytes to the endothelium. Proteomic analysis showed that HDL particles from patients had an altered composition compared to those of healthy subjects. We confirmed by western blot that low levels of apolipoprotein A4 (APOA4) and high of serum amyloid A1 (SAA1) in HDL were associated with the lack of anti-inflammatory function observed in aSAH. Our results indicate that the study of HDL in the pathophysiology of aSAH is needed, and functional HDL supplementation could be considered a novel therapeutic approach to the treatment of the inflammatory response after aSAH.

Acute oxygen sensing by vascular smooth muscle cells.

An adequate supply of oxygen (O2) is essential for most life forms on earth, making the delivery of appropriate levels of O2 to tissues a fundamental physiological challenge. When O2 levels in the alveoli and/or blood are low, compensatory adaptive reflexes are produced that increase the uptake of O2 and its distribution to tissues within a few seconds. This paper analyzes the most important acute vasomotor responses to lack of O2 (hypoxia): hypoxic pulmonary vasoconstriction (HPV) and hypoxic vasodilation (HVD). HPV affects distal pulmonary (resistance) arteries, with its homeostatic role being to divert blood to well ventilated alveoli to thereby optimize the ventilation/perfusion ratio. HVD is produced in most systemic arteries, in particular in the skeletal muscle, coronary, and cerebral circulations, to increase blood supply to poorly oxygenated tissues. Although vasomotor responses to hypoxia are modulated by endothelial factors and autonomic innervation, it is well established that arterial smooth muscle cells contain an acute O2 sensing system capable of detecting changes in O2 tension and to signal membrane ion channels, which in turn regulate cytosolic Ca2+ levels and myocyte contraction. Here, we summarize current knowledge on the nature of O2 sensing and signaling systems underlying acute vasomotor responses to hypoxia. We also discuss similarities and differences existing in O2 sensors and effectors in the various arterial territories.

The direct effect of fibroblast growth factor 23 on vascular smooth muscle cell phenotype and function.

BACKGROUND: In chronic kidney disease (CKD) patients, increased levels of fibroblast growth factor 23 (FGF23) are associated with cardiovascular mortality. The relationship between FGF23 and heart hypertrophy has been documented, however, it is not known whether FGF23 has an effect on vasculature. Vascular smooth muscle cells VSMCs may exhibit different phenotypes; our hypothesis is that FGF23 favours a switch from a contractile to synthetic phenotype that may cause vascular dysfunction. Our objective was to determine whether FGF23 may directly control a change in VSMC phenotype. METHODS: This study includes in vitro, in vivo and ex vivo experiments and evaluation of patients with CKD stages 2-3 studying a relationship between FGF23 and vascular dysfunction. RESULTS: In vitro studies show that high levels of FGF23, by acting on its specific receptor FGFR1 and Erk1/2, causes a change in the phenotype of VSMCs from contractile to synthetic. This change is mediated by a downregulation of miR-221/222, which augments the expression of MAP3K2 and PAK1. miR-221/222 transfections recovered the contractile phenotype of VSMCs. Infusion of recombinant FGF23 to rats increased vascular wall thickness, with VSMCs showing a synthetic phenotype with a reduction of miR-221 expression. Ex-vivo studies on aortic rings demonstrate also that high FGF23 increases arterial stiffening. In CKD 2-3 patients, elevation of FGF23 was associated with increased pulse wave velocity and reduced plasma levels of miR-221/222. CONCLUSION: In VSMCs, high levels of FGF23, through the downregulation of miR-221/222, causes a change to a synthetic phenotype. This change in VSMCs increases arterial stiffening and impairs vascular function, which might ultimately worsen cardiovascular disease.

Decrease in acute periprosthetic joint infections incidence with vancomycin-loaded calcium sulfate beads in patients with non-modifiable risk factors. A randomized clinical trial.

OBJECTIVES: The influence of local antibiotic therapy in orthopedic surgery remains unclear. In this trial, we evaluated the incidence of periprosthetic joint infections (PJI), after local or intravenous (IV) antibiotic prophylaxis. The aim of this intervention was to compare the PJI incidence in a population with non-modifiable risk factors after local prophylaxis with vancomycin-loaded calcium sulfate beads versus a control group. METHODS: A total of 83 subjects were evaluated, inclusion criteria included participants over 60 years of age, with at least one main risk factor for PJI who underwent total hip or knee joint replacement between June 2019 and May 2020. Cases were randomized, and the intervention group received local prophylactic antibiotic therapy with calcium sulfate beads impregnated with vancomycin; conventional IV prophylactic antibiotic therapy was administered for the control group. C-reactive protein (CRP) and erythrocyte sedimentation rate (ERS) serum biomarkers were analyzed on the day 5 and weeks 4, 8, and 12. When needed, the synovial fluid sample was obtained and cultured for the early acute PJI diagnosis. RESULTS: Acute PJI was found in 27 patients (67.5%) in the control group and 4 (9.3%) in the intervention group. The variable analysis identified that local prophylaxis with calcium sulfate beads reduces the incidence of acute knee or hip PJI in patients with non-modifiable risk factors compared to conventional prophylaxis (p < 0.0001) with a relative risk of 0.13 (CI:0.05-0.35). Length of hospital stay was also shorter in the intervention group at 4.6 days, compared to 15.25 days in the control group; p < 0.001. CONCLUSIONS: Local antibiotic prophylaxis in patients with non-modifiable risk factors undergoing hip or knee replacement reduces the incidence of acute PJI compared to IV antibiotics. CLINICAL TRIALS: NCT03976466 (clnicaltrials.gov) LEVEL OF EVIDENCE: II.

Membrane Cargo Density-Dependent Interaction between Protein and Lipid Domains on the Giant Unilamellar Vesicles.

Protein cargos anchored on the lipid membrane can be segregated by fluidic domain phase separation. Lipid membranes at certain compositions may separate into lipid domains to segregate cargos, and protein cargos themselves may be involved in protein condensate domain formation with multivalent binding proteins to segregate cargos. Recent studies suggest that these two driving forces of phase separation closely interact on the lipid membranes to promote codomain formation. In this report, we studied the effect of cargo density on the outcome of the cargo phase separation on giant unilamellar vesicles. Proteins and lipids are connected only by the anchored cargos, so it was originally hypothesized that higher cargo density would increase the degree of interaction between the lipid and protein domains, promoting more phase separation. However, fluorescence image analysis on different cargo densities showed that the cooperative domain formation and steric pressure are at a tug of war opposing each other. Cooperative domain formation is dominant under lower anchor density conditions, and above a threshold density, steric pressure was dominant opposing the domain formation. The result suggests that the cargo density is a key parameter affecting the outcome of cargo organization on the lipid membranes by phase separation.

Intelligent fluorescence image analysis of giant unilamellar vesicles using convolutional neural network.

BACKGROUND: Fluorescence image analysis in biochemical science often involves the complex tasks of identifying samples for analysis and calculating the desired information from the intensity traces. Analyzing giant unilamellar vesicles (GUVs) is one of these tasks. Researchers need to identify many vesicles to statistically analyze the degree of molecular interaction or state of molecular organization on the membranes. This analysis is complicated, requiring a careful manual examination by researchers, so automating the analysis can significantly aid in improving its efficiency and reliability. RESULTS: We developed a convolutional neural network (CNN) assisted intelligent analysis routine based on the whole 3D z-stack images. The programs identify the vesicles with desired morphology and analyzes the data automatically. The programs can perform protein binding analysis on the membranes or state decision analysis of domain phase separation. We also show that the method can easily be applied to similar problems, such as intensity analysis of phase-separated protein droplets. CNN-based classification approach enables the identification of vesicles even from relatively complex samples. We demonstrate that the proposed artificial intelligence-assisted classification can further enhance the accuracy of the analysis close to the performance of manual examination in vesicle selection and vesicle state determination analysis. CONCLUSIONS: We developed a MATLAB based software capable of efficiently analyzing confocal fluorescence image data of giant unilamellar vesicles. The program can automatically identify GUVs with desired morphology and perform intensity-based calculation and state decision for each vesicle. We expect our method of CNN implementation can be expanded and applied to many similar problems in image data analysis.

Toll-like receptors in neuroinflammation, neurodegeneration, and alcohol-induced brain damage.

Toll-like receptors (TLRs) or pattern recognition receptors respond to pathogen-associated molecular patterns (PAMPs) or internal damage-associated molecular patterns (DAMPs). TLRs are integral membrane proteins with both extracellular leucine-rich and cytoplasmic domains that initiate downstream signaling through kinases by activating transcription factors like AP-1 and NF-κB, which lead to the release of various inflammatory cytokines and immune modulators. In the central nervous system, different TLRs are expressed mainly in microglia and astroglial cells, although some TLRs are also expressed in oligodendroglia and neurons. Activation of TLRs triggers signaling cascades by the host as a defense mechanism against invaders to repair damaged tissue. However, overactivation of TLRs disrupts the sustained immune homeostasis-induced production of pro-inflammatory molecules, such as cytokines, miRNAs, and inflammatory components of extracellular vesicles. These inflammatory mediators can, in turn, induce neuroinflammation, and neural tissue damage associated with many neurodegenerative diseases. This review discusses the critical role of TLRs response in Alzheimer's disease, Parkinson's disease, ischemic stroke, amyotrophic lateral sclerosis, and alcohol-induced brain damage and neurodegeneration.

Role of Microbiota-Derived Extracellular Vesicles in Gut-Brain Communication.

Human intestinal microbiota comprise of a dynamic population of bacterial species and other microorganisms with the capacity to interact with the rest of the organism and strongly influence the host during homeostasis and disease. Commensal and pathogenic bacteria coexist in homeostasis with the intestinal epithelium and the gastrointestinal tract's immune system, or GALT (gut-associated lymphoid tissue), of the host. However, a disruption to this homeostasis or dysbiosis by different factors (e.g., stress, diet, use of antibiotics, age, inflammatory processes) can cause brain dysfunction given the communication between the gut and brain. Recently, extracellular vesicles (EVs) derived from bacteria have emerged as possible carriers in gut-brain communication through the interaction of their vesicle components with immune receptors, which lead to neuroinflammatory immune response activation. This review discusses the critical role of bacterial EVs from the gut in the neuropathology of brain dysfunctions by modulating the immune response. These vesicles, which contain harmful bacterial EV contents such as lipopolysaccharide (LPS), peptidoglycans, toxins and nucleic acids, are capable of crossing tissue barriers including the blood-brain barrier and interacting with the immune receptors of glial cells (e.g., Toll-like receptors) to lead to the production of cytokines and inflammatory mediators, which can cause brain impairment and behavioral dysfunctions.

A targeted polypeptide-based nanoconjugate as a nanotherapeutic for alcohol-induced neuroinflammation.

Alcohol abuse induces the expression of inflammatory mediators by activating the immune receptors to trigger neuroinflammation and brain damage; however, therapies that reduce neuroimmune system activation may protect against alcohol's damaging effects. Curcuminoids possess anti-inflammatory properties but suffer from low bioavailability; therefore, we designed a new receptor-targeted biodegradable star-shaped crosslinked polypeptide polymer that bears propargylamine moieties and bisdemethoxycurcumin (StClPr-BDMC-ANG) as an enhanced anti-inflammatory therapeutic that penetrates the blood-brain-barrier and ameliorates alcohol-induced neuroinflammation. StClPr-BDMC-ANG administration maintains the viability of primary glia and inhibits the ethanol-induced upregulation of crucial inflammatory mediators in the prefrontal and medial cortex in a mouse model of chronic ethanol consumption. StClPr-BDMC-ANG treatment also suppresses the ethanol-mediated downregulation of microRNAs known to negatively modulate neuroinflammation in the brain cortex (miRs 146a-5p and let-7b-5p). In summary, our results demonstrate the attenuation of alcohol-induced neuroinflammation by an optimized and targeted polypeptide-based nanoconjugate of a curcuminoid.

PKCα-Mediated Downregulation of RhoA Activity in Depolarized Vascular Smooth Muscle: Synergistic Vasorelaxant Effect of PKCα and ROCK Inhibition.

BACKGROUND/AIMS: Protein kinase C (PKC)- and RhoA/Rho-associated kinase (ROCK) play important roles in arterial sustained contraction. Although depolarization-elicited RhoA/ROCK activation is accepted, the role of PKC in depolarized vascular smooth muscle cells (VSMCs) is a subject of controversy. Our aim was to study the role of PKC in arterial contraction and its interaction with RhoA/ROCK. METHODS: Mass spectrometry was used to identify the PKC isoenzymes. PKCα levels and RhoA activity were analyzed by western blot and G-LISA, respectively, and isometric force was measured in arterial rings. RESULTS: In depolarized VSMCs RhoA and PKCα were translocated to the plasma membrane, where they colocalize and coimmunoprecipitate. Interestingly, depolarization-induced RhoA activation was downregulated by PKCα, effect reverted by PKCα inhibition. Phorbol 12,13-dibutyrate (PDBu) induced the translocation of PKCα to the plasma membrane, increased the level of RhoA in the cytosol and reduced RhoA/ROCK activity. These effects were reverted when PKC was inhibited. Pharmacological or siRNA inhibition of PKCα synergistically potentiated the vasorelaxant effect of RhoA/ROCK inhibition. CONCLUSION: The present study provides the first evidence that RhoA activity is downregulated by PKCα in depolarized and PDBu treated freshly isolated VSMCs and arteries, with an important physiological role on arterial contractility.

Contribution of L-type Ca2+ channel-sarcoplasmic reticulum coupling to depolarization-induced arterial contraction in spontaneously hypertensive rats.

Evidence has shown that vascular smooth muscle cells (VSMCs) of spontaneously hypertensive rats (SHRs) are depolarized and that the expression of L-type Ca2+ channels (LTCCs) and the sarcoplasmic reticulum (SR) Ca2+ buffering system are upregulated. Arterial rings exposed to high K+ solutions develop a contraction with two components, namely, an initial or phasic component and a sustained or tonic component. Because LTCCs and SR have different functions in the phasic and tonic components of depolarization-induced contraction, this study investigated the role of LTCC-SR coupling in depolarized arterial rings of SHRs. In the absence of extracellular Ca2+, high external K+ or LTCC agonists elicited a transitory contraction, which was sensitive to nifedipine and was potentiated in SHRs. In the presence of extracellular Ca2+, cyclopiazonic acid (CPA), an SR Ca2+-ATPase (SERCA) inhibitor, evoked a transient contraction that was significantly increased in SHRs. Although the phasic and tonic components were markedly increased in depolarized arterial rings of SHRs, they showed different voltage-dependence and sensitivity to SERCA inhibition. The tonic component was more sensitive to moderate depolarizations, and CPA selectively reduced the tonic component to the level observed in WKY rats. These results suggested that LTCC-SR coupling is potentiated in the sustained contraction of hypertensive VSMCs.

Relation of RhoA in Peripheral Blood Mononuclear Cells With Severity of Aneurysmal Subarachnoid Hemorrhage and Vasospasm.

BACKGROUND AND PURPOSE: Rho-kinase, an effector of RhoA, is associated with various cardiovascular diseases in circulating blood cells. However, the role of RhoA/Rho-kinase in peripheral blood mononuclear cells from patients with spontaneous aneurysmal subarachnoid hemorrhage (aSAH) has not yet been studied in relation to the severity of this disease. Therefore, we analyzed the expression and activity of RhoA as a possible biomarker in aSAH. METHODS: Twenty-four patients with aSAH and 15 healthy subjects were examined. Peripheral blood mononuclear cells were collected, and RhoA activity and expression were determined by RhoA activation assay kit (G-LISA) and enzyme-linked immunosorbent assay tests, respectively. The severity of aSAH was determined from the World Federation of Neurological Surgeon scale, and vasospasm was evaluated using clinical symptoms, arteriography, and sonography. RESULTS: RhoA expression was significantly increased in peripheral blood mononuclear cells from patients on days 0, 2, and 4 after aSAH versus healthy subjects (P=0.036, 0.010, and 0.018, respectively, by U Mann-Whitney analysis). There was a significant correlation between RhoA expression and injury severity on days 2 and 4 (Spearman test, day 2: r=0.682, n=14, P=0.007; day 4: r=0.721, n=14, P=0.004). No significant correlation was observed on day 0 (day 0: r=0.131, n=6, P=0.805). Active RhoA was not significantly different in patients and healthy subjects on days 0, 2, and 4 (P=0.243, 0.222, and 0.600, respectively) nor did it increase significantly on days 0 and 2 in patients with vasospasm versus patients without vasospasm (P=0.064 and 0.519, respectively). In contrast, active RhoA was significantly higher on day 4 in patients who developed vasospasm versus patients without vasospasm (P=0.028). CONCLUSIONS: Our preliminary results indicate that RhoA expression and activity in peripheral blood mononuclear cells might be related with aSAH severity and cerebral vasospasm. RhoA is a potential biomarker of the risks associated with aSAH.

Regulation of RhoA/ROCK and sustained arterial contraction by low cytosolic Ca2+ levels during prolonged depolarization of arterial smooth muscle.

The role of L-type Ca2+ channels (LTCCs) and RhoA/Rho kinase (ROCK) on depolarization-induced sustained arterial contraction lasting several minutes is already known. However, in vivo, vascular smooth muscle cells can be depolarized for longer periods, inducing substantial inactivation of LTCCs and markedly reducing Ca2+ influx into the myocytes. We have examined, in femoral arterial rings, the role of LTCCs and RhoA/ROCK during long-lasting depolarization. Our results reveal a new vasoreactive response after 20-30min of depolarization in 2.5mM external Ca2+ that has not been identified previously with shorter stimuli. Prolonged depolarization-induced arterial contraction was permanently abolished when arterial rings were treated with 100nM external Ca2+ or 20nM nifedipine. However, when Ca2+ influx was restricted, applying ~7µM external Ca2+ solution or 3nM nifedipine, vasorelaxation was transient, and isometric force slowly increased after 30min and maintained its level until the end of the stimulus. Under these conditions, arterial contraction showed the same temporal course of RhoA activity and was sensitive to fasudil, nifedipine and cyclopiazonic acid. Ca2+-response curve in ß-escin permeabilized arteries was also sensitive to ROCK inhibitors. Thus, although long-lasting depolarization inactivates LTCCs, the reduced Ca2+ entry can induce a detectable arterial contraction via RhoA/ROCK activation.

Role of L-type Ca(2+) channels, sarcoplasmic reticulum and Rho kinase in rat basilar artery contractile properties in a new model of subarachnoid hemorrhage.

We have previously described that L-type Ca(2+) channels' (LTCCs) activation and metabotropic Ca(2+) release from the sarcoplasmic reticulum (SR) regulate RhoA/Rho kinase (ROCK) activity and sustained arterial contraction. We have investigated whether this signaling pathway can be altered in a new experimental model of subarachnoid hemorrhage (SAH). For this purpose, arterial reactivity was evaluated on days 1 to 5 after surgery. A significant increase of basal tone, measured 4 and 60min after normalization, was observed on day 5 after SAH and at 60min on days 2 and 3 after SAH. This phenomenon was suppressed with LTCCs and ROCK inhibitors. We have also studied arterial rings vasoreactivity in response to high K(+) solutions. Interestingly, there were no significant differences in the phasic component of the high K(+)-induced contraction between sham and SAH groups, whereas a significant increase in the sustained contraction was observed on day 5 after SAH. This latter component was sensitive to fasudil, and selectively reduced by low nifedipine concentration, and phospholipase C and SR-ATPase inhibitors. Therefore, our data suggest that the metabotropic function of LTCCs is potentiated in SAH. Our results could provide a new strategy to optimize the pharmacological treatment of this pathological process.

Low-dose combination of Rho kinase and L-type Ca(2+) channel antagonists for selective inhibition of depolarization-induced sustained arterial contraction.

L-type Ca(2+) channels (LTCCs) are involved in the maintenance of tonic arterial contractions and regulate the RhoA/Rho-associated kinase (ROCK) sensitization cascade. We have tested effects of individual and combined low concentrations of LTCCs and ROCK inhibitors to produce arterial relaxation without the adverse side effects of LTCCs antagonists. We have also studied whether this pharmacological strategy alters Ca(2+)-dependent electrical properties of isolated arterial and cardiac myocytes as well as cardiac contractility. Rat basilar, human carotid and coronary arterial rings were mounted on a small-vessel myograph to measure isometric tension and cardiac contractility was measured in Langendorff-perfused rat heart. Simultaneous cytosolic Ca(2+) concentration and arterial diameter were measured in intact pressurized arteries loaded with Fura-2. Patch-clamp techniques were used to measure electrical properties in isolated cardiac and arterial myocytes. Low concentrations of LTCCs and ROCK inhibitors reduced the tonic component of moderate depolarization-evoked contraction, leaving the phasic component practically unaltered. This selective vasorelaxant effect was more marked when the LTCCs and ROCK inhibitors were applied together. In the concentration range used (nM), Ca(2+) currents in arterial myocytes, cardiac action potentials and heart contractility were unaffected by this pharmacological approach. In conclusion, low doses of LTCCs and ROCK inhibitors could be used to selectively relax precontracted arteries in pathologic conditions such as hypertension, and cerebral or coronary spasms with minor side effects on physiological contractile properties of vascular and cardiac myocytes.

Contractile responses to rat urotensin II in resting and depolarized basilar arteries

The effects of human urotensin II (hUII) on the vascular tone of different animal species has been studied extensively. However, little has been reported on the vasoactive effects of rat urotensin (rUII) in murine models. The aim of the present study was to investigate the effects of rUII on vasoreactivity in rat basilar arteries. Basilar arteries from adult male Wistar rats (300-350 g) were isolated, cut in rings, and mounted on a small vessel myograph to measure isometric tension. rUII concentrations were studied in both resting and depolarized state. To remove endothelial nitric oxide effects from the rUII response, we treated selected arterial rings with Nω-nitro-L-arginine methyl ester (L-NAME). 10 μM rUII produced a potent vasoconstrictor response in rat basilar arteries with intact endothelium, while isometric forces remained unaffected in arterial rings treated with lower rUII concentrations. Although L-NAME did not have a significant effect on 10 μM rUII-evoked contraction, it slightly increased arterial ring contraction elicited by 1 μM rUII. In depolarized arteries, dose-dependent rUII increased depolarization-induced contractions. This effect was suppressed by L-NAME. Our results show that the rat basilar artery has a vasoconstrictor response to rUII. The most potent vasoconstrictor effect was produced by lower doses of rUII (0.1 and 1 μM) in depolarized arteries with intact endothelium. This effect could facilitate arterial vasospasm in vascular pathophysiological processes such as subarachnoid hemorrhage and hypertension, when sustained depolarization and L-type Ca2+ channel activation are present

Contractile responses to rat urotensin II in resting and depolarized basilar arteries.

The effects of human urotensin II (hUII) on the vascular tone of different animal species has been studied extensively. However, little has been reported on the vasoactive effects of rat urotensin (rUII) in murine models. The aim of the present study was to investigate the effects of rUII on vasoreactivity in rat basilar arteries. Basilar arteries from adult male Wistar rats (300-350 g) were isolated, cut in rings, and mounted on a small vessel myograph to measure isometric tension. rUII concentrations were studied in both resting and depolarized state. To remove endothelial nitric oxide effects from the rUII response, we treated selected arterial rings with Nω-nitro-L-arginine methyl ester (L-NAME). 10 µM rUII produced a potent vasoconstrictor response in rat basilar arteries with intact endothelium, while isometric forces remained unaffected in arterial rings treated with lower rUII concentrations. Although L-NAME did not have a significant effect on 10 µM rUII-evoked contraction, it slightly increased arterial ring contraction elicited by 1 µM rUII. In depolarized arteries, dose-dependent rUII increased depolarization-induced contractions. This effect was suppressed by L-NAME. Our results show that the rat basilar artery has a vasoconstrictor response to rUII. The most potent vasoconstrictor effect was produced by lower doses of rUII (0.1 and 1 µM) in depolarized arteries with intact endothelium. This effect could facilitate arterial vasospasm in vascular pathophysiological processes such as subarachnoid hemorrhage and hypertension, when sustained depolarization and L-type Ca(2+) channel activation are present.