'Altered' mesenteric artery SK(Ca) : functional implications?
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ABSTRACT:
SUBMITTER: Sandow S
PROVIDER: S-EPMC3144527 | biostudies-literature | 2011 Jul
REPOSITORIES: biostudies-literature
Publications
'Altered' mesenteric artery SK(Ca) : functional implications?
Sandow Shaun S Grayson T Hilton TH
British journal of pharmacology 20110701 6
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Project description:Background and purposeLysophosphatidylinositol (LPI), a lipid signalling molecule, activates GPR55 and elevates intracellular Ca(2+). Here, we examine the actions of LPI in the rat resistance mesenteric artery and Ca(2+) responses in endothelial cells isolated from the artery.Experimental approachVascular responses were studied using wire myographs. Single-cell fluorescence imaging was performed using a MetaFluor system. Hypotensive effects of LPI were assessed using a Biopac system.Key resultsIn isolated arteries, LPI-induced vasorelaxation was concentration- and endothelium-dependent and inhibited by CID 16020046, a GPR55 antagonist. The CB1 receptor antagonist AM 251 had no effect, whereas rimonabant and O-1918 significantly potentiated LPI responses. Vasorelaxation was reduced by charybdotoxin and iberiotoxin, alone or combined. LPI decreased systemic arterial pressure. GPR55 is expressed in rat mesenteric artery. LPI caused biphasic elevations of endothelial cell intracellular Ca(2+). Pretreatment with thapsigargin or 2-aminoethoxydiphenyl borate abolished both phases. The PLC inhibitor U73122 attenuated the initial phase and enhanced the second phase, whereas the Rho-associated kinase inhibitor Y-27632 abolished the late phase but not the early phase.Conclusions and implicationsLPI is an endothelium-dependent vasodilator in the rat small mesenteric artery and a hypotensive agent. The vascular response involves activation of Ca(2+)-sensitive K(+) channels and is not mediated by CB1 receptors, but unexpectedly enhanced by antagonists of the 'endothelial anandamide' receptor. In endothelial cells, LPI utilizes PLC-IP3 and perhaps ROCK-RhoA pathways to elevate intracellular Ca(2+). Overall, these findings support an endothelial site of action for LPI and suggest a possible role for GPR55 in vasculature.
| S-EPMC4459022 | biostudies-literature
Project description:Small conductance calcium (Ca(2+)) activated SK channels are critical regulators of neuronal excitability in hippocampus. Accordingly, these channels are thought to play a key role in controlling neuronal activity in acute models of epilepsy. In this study, we investigate the expression and function of SK channels in the pilocarpine model of mesial temporal lobe epilepsy. For this purpose, protein expression was assessed using western blotting assays and gene expression was analyzed using TaqMan-based probes and the quantitative real-time polymerase chain reaction (qPCR) comparative method delta-delta cycle threshold ( big up tri, open big up tri, openCT) in samples extracted from control and epileptic rats. In addition, the effect of SK channel antagonist UCL1684 and agonist NS309 on CA1 evoked population spikes was studied in hippocampal slices. Western blotting analysis showed a significant reduction in the expression of SK1 and SK2 channels at 10days following status epilepticus (SE), but levels recovered at 1month and at more than 2months after SE. In contrast, a significant down-regulation of SK3 channels was detected after 10days of SE. Analysis of gene expression by qPCR revealed a significant reduction of transcripts for SK2 (Kcnn1) and SK3 (Kcnn3) channels as early as 10days following pilocarpine-induced SE and during the chronic phase of the pilocarpine model. Moreover, bath application of UCL1684 (100nM for 15min) induced a significant increase of the population spike amplitude and number of spikes in the hippocampal CA1 area of slices obtained control and chronic epileptic rats. This effect was obliterated by co-administration of UCL1684 with SK channel agonist NS309 (1microM). Application of NS309 failed to modify population spikes in the CA1 area of slices taken from control and epileptic rats. These data indicate an abnormal expression of SK channels and a possible dysfunction of these channels in experimental MTLE.
| S-EPMC2916930 | biostudies-literature
Project description:1. Nine bis-quinolinyl and bis-quinolinium compounds related to dequalinium, and previously shown to block apamin-sensitive small conductance Ca(2+)-activated K(+) channels (SK(Ca)), have been tested for their inhibitory effects on actions mediated by intermediate conductance Ca(2+)-activated K(+) channels (IK(Ca)) in rabbit blood cells. 2. In most experiments, a K(+)-sensitive electrode was employed to monitor the IK(Ca)-mediated net loss of cell K(+) that followed the addition of the Ca(2+) ionophore A23187 (2 microM) to red cells suspended at an haematocrit of 1% in a low K(+) (0.12 - 0.17 mM) solution. The remainder used an optical method based on measuring the reduction in light transmission that occurred on applying A23187 (0.4 or 2 microM) to a very dilute suspension of red cells (haematocrit 0.02%). 3. Of the compounds tested, the most potent IK(Ca) blocker was 1,12 bis[(2-methylquinolin-4-yl)amino]dodecane (UCL 1407) which had an IC(50) of 0.85+/-0.06 microM (mean+/-s.d. mean). 4. The inhibitory action of UCL 1407 and its three most active congeners was characterized by (i) a Hill slope greater than unity, (ii) sensitivity to an increase in external [K(+)], and (iii) a time course of onset that suggested use-dependence. Also, the potency of the nonquaternary compounds tested increased with their predicted lipophilicity. These findings suggested that the IK(Ca) blocking action resembles that of cetiedil rather than of clotrimazole. 5. Some quaternized members of the series were also active. The most potent was the monoquaternary UCL 1440 ((1-[N-[1-(3, 5-dimethoxybenzyl)-2-methylquinolinium-4-yl]amino]-10-[N'-(2-me thylqu inolinium-4yl)amino] decane (trifluoroacetate) which had an IC(50) of 1.8+/-0.1 microM. The corresponding bisquaternary UCL 1438 (1, 10-bis[N-[1-(3,5-dimethoxybenzyl)-2-methylquinolinium-4-yl]amino] decane bis(trifluoroacetate) was almost as active (IC(50) 2.7+/-0.3 microM). 6. A bis-aminoquinolium cyclophane (UCL 1684) had little IK(Ca) blocking action despite its great potency at SK(Ca) channels (IC(50) 4.1+/-0.2 nM). 7. The main outcome is the identification of new intermediate-conductance Ca(2+)-activated K(+) channel blockers with a wide range of IK(Ca)/SK(Ca) selectivities.
| S-EPMC1571984 | biostudies-literature
Project description:Calcium-sensitive potassium (K(Ca)) channels have been shown to modulate the diameter of cerebral pial arteries; however, little is known regarding their roles in controlling cerebral parenchymal arterioles (PAs). We explored the function and cellular distribution of small-conductance (SK(Ca)) and intermediate-conductance (IK(Ca)) K(Ca) channels and large-conductance K(Ca) (BK(Ca)) channels in endothelial cells (ECs) and smooth muscle cells (SMCs) of PAs. Both SK(Ca) and IK(Ca) channels conducted the outward current in isolated PA ECs (current densities, ~20?pA/pF and ~28?pA/pF at +40?mV, respectively), but these currents were not detected in PA SMCs. In contrast, BK(Ca) currents were prominent in PA SMCs (~154?pA/pF), but were undetectable in PA ECs. Pressurized PAs constricted to inhibition of SK(Ca) (~16%) and IK(Ca) (~16%) channels, but were only modestly affected by inhibition of BK(Ca) channels (~5%). Blockade of SK(Ca) and IK(Ca) channels decreased resting cortical cerebral blood flow (CBF) by ~15%. NS309 (6,7-dichloro-1H-indole-2,3-dione3-oxime), a SK(Ca)/IK(Ca) channel opener, hyperpolarized PA SMCs by ~27?mV, maximally dilated pressurized PAs, and increased CBF by ~40%. In conclusion, these data show that SK(Ca) and IK(Ca) channels in ECs profoundly modulate PA tone and CBF, whereas BK(Ca) channels in SMCs only modestly influence PA diameter.
| S-EPMC3099631 | biostudies-literature
Project description:Treatment of sarcoplasmic reticulum vesicles with diethylpyrocarbonate in the presence of a large excess of reagent, at pH 6.2 and at room temperature, reveals both a fast- and a slow-reacting population of protein residues. The loss of the Ca(2+)-ATPase activity is mainly associated with the fast-reacting population being partially sensitive to hydroxylamine. There is also an effect on the Ca(2+)-binding mechanism. Shorter derivatization times (5 min) produce a loss of the positive cooperativity of Ca2+ binding. When the treatment was prolonged for 30 min there was an additional decrease in the overall Ca2+ affinity. Curve-fitting procedures applied to the non-cooperative binding isotherms provide the equilibrium constants for the two Ca2+ sites, although they cannot discriminate between interacting and independent site mechanisms. Prestationary kinetics assays show 2 Ca2+:1 ATP ratios, at any extent of Ca2+ saturation, indicating that the Ca2+ sites are not independent. The Ca2+ dissociation profile after derivatization shows a decrease in the dissociation constant for the release of the second Ca2+, which is consistent with interacting sites. Isotopic exchange experiments show fast and slow components of equal amplitude even at subsaturating Ca2+ concentrations, which is incompatible with independent binding sites. The experimental data suggest a modification of the equilibrium binding constants making them more similar, but keeping the interacting character. The structural position of the external (cytoplasmic) and the internal (lumenal) Ca2+ sites remains unaltered in the absence of positive cooperativity.
| S-EPMC1135759 | biostudies-other
Project description:The aim of this study was to analyze the superior mesenteric artery (SMA) remodeling after initial conservative or endovascular treatment with a standardized definition and midterm outcomes in patients with spontaneous isolated dissection of the superior mesenteric artery (SIDSMA). This retrospective study enrolled patients with SIDSMA from January 2007 to August 2019. All patients were treated initially with conservative treatment. If they failed the medical treatment, they were converted to interventional treatment. The morphological endpoint was determined by the standardized SMA remodeling, and the clinical endpoints were determined by the in-hospital mortality, hospital stay, and the bowel-related mid-term mortality. A total of 34 consecutive patients with SIDSMA were identified. Twenty-three (67.6%) and eleven (33.4%) patients underwent conservative and interventional treatments, respectively. Clinical features and morphologic changes on CTA were available in 25 (73.5%) patients during the median follow-up of 23.3 months. Standardized SMA remodeling was significantly (p < 0.05) better in patients undergoing endovascular stenting, especially in patients with Yun's IIb classification. There was no mesenteric ischemia or SMA aneurysm during follow-up period. Patients with SIDSMA can be treated safely with initial conservative treatment. However, significant portions of patients will require endovascular intervention due to the persistent symptoms. Clinically endovascular stenting could be performed successfully, and SMA remodeling was satisfactory during the mid-term follow-up.
| S-EPMC8777763 | biostudies-literature
Project description: Not available
| S-EPMC10448315 | biostudies-literature
Project description:BackgroundTo investigate the application of the superior mesenteric artery (SMA) for the in vitro reconstruction of the hepatic artery for liver transplantation, and to improve the success rate and safety of donor liver transplantation.MethodsThe donor liver and the pancreas were obtained, and the SMA and its branches were used to reconstruct the hepatic artery. Liver transplantation was performed after reconstruction to understand the intraoperative situation after donor liver opening, as well as postoperative liver function. Color Doppler ultrasound of the transplanted liver was also performed.ResultsDuring the period from September 2016 to March 2020, a total of 98 pancreases were obtained. The common hepatic artery and gastroduodenal artery loop (CHA-GDA) were preserved to the donor pancreas, and only the proper hepatic artery (PHA) or left/right hepatic artery (LHA/RHA) were preserved to the donor liver. If the PHA of the donor liver was short or absent, the SMA was used for lengthening the PHA or in vitro reconstruction of the LHA/RHA, followed by implantation of the donor liver after reconstruction. A total of 17 cases of this type of donor liver required mesenteric artery lengthening or reconstruction. After opening, the donor liver was well-filled, bile secretion was normal, and liver function recovered as scheduled after surgery. Color Doppler ultrasound and CT angiography (CTA) of the transplanted liver revealed that hepatic arteries were normal without complications such as hepatic artery embolism.ConclusionsIn vitro reconstruction of the hepatic artery with the SMA is an effective new method of vascular reconstruction, which ensures the blood flow of the hepatic artery, reduces the anastomosis difficulty of the arteries of the donor liver, and reduces the occurrence of vascular complications.
| S-EPMC7729337 | biostudies-literature
Project description:Key clinical messageThe robotic modified Strong procedure is a safe and effective approach for surgical management of superior mesenteric artery syndrome in properly selected patients.AbstractSuperior mesenteric artery syndrome is a rare syndrome of small bowel obstruction resulting from vascular compression of the duodenum. Here we present our modification of a robotic Strong procedure for the surgical management of SMA syndrome. This procedure is a safe and effective approach for management in properly selected patients.
| S-EPMC10350670 | biostudies-literature
Project description:The superior mesenteric artery (SMA) is one of the visceral branches of the abdominal aorta. It has multiple branches to supply blood and nutrition to the intestinal segment, and these form an anastomosis with each other. SMA injuries are usually classified as major visceral artery injuries, and have an incidence of <1%. The clinical manifestations of patients with SMA injuries include intra-abdominal bleeding and peritoneal irritation. The compromised blood supply can lead to intestinal ischemia and perforation. These injuries are often not diagnosed in time and have significant mortality rates of 25%-68% due to the lack of specific features (Maithel et al., 2020). Not only that, but patients with less severe trauma or no visible damage on initial examination may still have clinically significant intra-abdominal injuries (Nishijima et al., 2012). Emergency departments often encounter multiple cases that require urgent diagnosis and treatment (Li et al., 2021; Zhang et al., 2021; Zhou et al., 2021), and therefore, it is imperative to diagnose and manage these rare injuries expeditiously.
| S-EPMC9758718 | biostudies-literature