共查询到20条相似文献,搜索用时 31 毫秒
1.
B.I. García-GómezF.I.V. Coronas R. Restano-CassuliniR.R. Rodríguez L.D. Possani 《Toxicon》2011,58(1):18-27
This communication describes the first general biochemical, molecular and functional characterization of the venom from the Cuban blue scorpion Rhopalurus junceus, which is often used as a natural product for anti-cancer therapy in Cuba. The soluble venom of this arachnid is not toxic to mice, injected intraperitoneally at doses up to 200 μg/20 g body weight, but it is deadly to insects at doses of 10 μg per animal. The venom causes typical alpha and beta-effects on Na+ channels, when assayed using patch-clamp techniques in neuroblastoma cells in vitro. It also affects K+ currents conducted by ERG (ether-a-go-go related gene) channels. The soluble venom was shown to display phospholipase, hyaluronidase and anti-microbial activities. High performance liquid chromatography of the soluble venom can separate at least 50 components, among which are peptides lethal to crickets. Four such peptides were isolated to homogeneity and their molecular masses and N-terminal amino acid sequence were determined. The major component (RjAa12f) was fully sequenced by Edman degradation. It contains 64 amino acid residues and four disulfide bridges, similar to other known scorpion toxins. A cDNA library prepared from the venomous glands of one scorpion allowed cloning 18 genes that code for peptides of the venom, including RjA12f and eleven other closely related genes. Sequence analyses and phylogenetic reconstruction of the amino acid sequences deduced from the cloned genes showed that this scorpion contains sodium channel like toxin sequences clearly segregated into two monophyletic clusters. Considering the complex set of effects on Na+ currents verified here, this venom certainly warrant further investigation. 相似文献
2.
Naiara Schaffazick Tatiane F. Fonseca Glauco A. Gaban Sabrina Calil-Elias Paulo A. Melo Valéria M.N. Cunha 《Toxicon》2010,55(1):52-60
Ca2+ ions are essential to myonecrosis, a serious complication of snake envenomation, and heparin seems to counteract this effect. We investigated the effect of local injection of Bothrops jararacussu venom in mouse fast-twitch extensor digitorum longus (EDL) muscle, without or with heparin, on functional/molecular alterations of two central proteins involved in intracellular Ca2+ homeostasis, sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) and Na+/K+-ATPase. EDL-specific SERCA1 isoform expression dropped significantly just after venom administration (up to 60% compared to control EDL values at days 1 and 3; p < 0.05) while SERCA2 and Na+/K+-ATPase α1 isoform expression increased at the same time (3-6- and 2-3-fold, respectively; p < 0.05). Although not significant, Na+/K+-ATPase α2 isoform followed the same trend. Except for SERCA2, all proteins reached basal levels at the 7th day. Intravenous heparin treatment did not affect these profiles. Ca2+-ATPase activity was also decreased during the first days after venom injection, but here heparin was effective to reinstate activity to control levels within 3 days. We also showed that B. jararacussu venom directly inhibited Ca2+-ATPase activity in a concentration-dependent manner. Our results indicate that EDL SERCA and Na+/K+-ATPase are importantly affected by B. jararacussu venom and heparin has protective effect on activity but not on protein expression. 相似文献
3.
Amal J. Fatani 《Saudi Pharmaceutical Journal》2010,18(3):137-151
Background
Scorpion envenomation is common among desert dwellers, affecting several systems and resulting in multiple organ dysfunction (MOD) or failure (MOF), mainly due to their action on Na+ channels. Although scorpion venoms toxins do not pass the blood brain barrier, their CNS effects are prominent, occurring in conjunction with, or as an aftermath of peripheral actions of the venom.Objective
To determine the ability of venom of the common scorpion Leiurus quinquestriatus (LQQ) to induce MOD or MOF when injected into rabbits in micro quantities centrally (intracerebroventricularly, i.c.v.) or macro amounts peripherally (s.c. or i.v.). Also, to assess if the Na+ channel blocker lidocaine can protect rabbits from the resultant manifestations.Methods
Rabbits were injected with LQQ venom centrally or peripherally, in either sublethal or lethal doses, and MOD or MOF determined by assessing: cardiac output (CO), estimated hepatic blood flow (EHBF), biochemical parameters indicative of cardiac/hepatic/renal and pancreatic functions, blood pressure (BP), survival, lung/body index (LBI, indicative of pulmonary edema), and/or histological changes in hearts, lungs, livers plus kidneys. In pre-treatment experiments, lidocaine was injected 40 min before venom and protective ability examined.Results
LQQ venom in sublethal doses caused comparable significant reductions (vs control) in CO and EHBF when injected i.c.v. (2 μg kg−1) or s.c. (0.2 mg kg−1). Both routes caused gradual dose-related enhanced levels of creatine kinase, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, creatinine, glucose and amylase, indicating MOD. Also, characteristic venom-induced changes in BP were evident after lethal doses of venom i.v. (0.5 mg kg−1) or i.c.v. (3 μg kg−1). Histological changes in the organs plus LBI were comparable after i.c.v. and i.v. venom injection, with animals ultimately exhibiting MOF. Lidocaine (1 mg kg−1 i.v., then infusion 50 μg kg−1 min−1, 30 min before venom), protected the animals from MOF evoked by lethal doses of the venom (whether injected centrally or peripherally), as evidenced by the amelioration of the venom’s effects on blood pressure, LBI, survival and multiple organ histopathological manifestations.Conclusion
LQQ venom, whether injected centrally or peripherally caused comparable systemic dose-dependent MOD or MOF, with the latter attenuated by the Na+ channel blocker lidocaine, indicating a role for Na+ channels. 相似文献4.
Lina T Al Kury Oleg I Voitychuk Keun-Hang Susan Yang Faisal T Thayyullathil Petro Doroshenko Ali M Ramez Yaroslav M Shuba Sehamuddin Galadari Frank Christopher Howarth Murat Oz 《British journal of pharmacology》2014,171(14):3485-3498
BACKGROUND AND PURPOSE
The endocannabinoid anandamide (N-arachidonoyl ethanolamide; AEA) exerts negative inotropic and antiarrhythmic effects in ventricular myocytes.EXPERIMENTAL APPROACH
Whole-cell patch-clamp technique and radioligand-binding methods were used to analyse the effects of anandamide in rat ventricular myocytes.KEY RESULTS
In the presence of 1–10 μM AEA, suppression of both Na+ and L-type Ca2+ channels was observed. Inhibition of Na+ channels was voltage and Pertussis toxin (PTX) – independent. Radioligand-binding studies indicated that specific binding of [3H] batrachotoxin (BTX) to ventricular muscle membranes was also inhibited significantly by 10 μM metAEA, a non-metabolized AEA analogue, with a marked decrease in Bmax values but no change in Kd. Further studies on L-type Ca2+ channels indicated that AEA potently inhibited these channels (IC50 0.1 μM) in a voltage- and PTX-independent manner. AEA inhibited maximal amplitudes without affecting the kinetics of Ba2+ currents. MetAEA also inhibited Na+ and L-type Ca2+ currents. Radioligand studies indicated that specific binding of [3H]isradipine, was inhibited significantly by metAEA. (10 μM), changing Bmax but not Kd.CONCLUSION AND IMPLICATIONS
Results indicate that AEA inhibited the function of voltage-dependent Na+ and L-type Ca2+ channels in rat ventricular myocytes, independent of CB1 and CB2 receptor activation. 相似文献5.
Tefluthrin is a synthetic pyrethroid and involved in acute neurotoxic effects. How this compound affects ion currents in endocrine or neuroendocrine cells remains unclear. Its effects on membrane ion currents in pituitary tumor (GH3) cells and in hypothalamic (GT1-7) neurons were investigated. Application of Tef (10 μM) increased the amplitude of voltage-gated Na+ current (INa), along with a slowing in current inactivation and deactivation in GH3 cells. The current–voltage relationship of INa was shifted to more negative potentials in the presence of this compound. Tef increased INa with an EC50 value of 3.2 ± 0.8 μM. It also increased the amplitude of persistent INa. Tef reduced the amplitude of L-type Ca2+ current. This agent slightly inhibited K+ outward current; however, it had no effect on the activity of large-conductance Ca2+-activated K+ channels. Under cell-attached voltage-clamp recordings, Tef (10 μM) increased amplitude and frequency of spontaneous action currents, along with appearance of oscillatory inward currents. Tef-induced inward currents were suppressed after further application of tetrodotoxin, riluzole or ranolazine. In GT1-7 cells, Tef also increased the amplitude and frequency of action currents. Taken together, the effects of Tef and its structural related pyrethroids on ion currents can contribute to the underlying mechanisms through which they affect endocrine or neuroendocrine function in vivo. 相似文献
6.
The effects of Pacific ciguatoxin-4B (P-CTX-4B, also named gambiertoxin), extracted from toxic Gambierdiscus dinoflagellates, were assessed on nodal K+ and Na+ currents of frog myelinated axons, using a conventional voltage-clamp technique. P-CTX-4B decreased, within a few minutes, both K+ and Na+ currents in a dose-dependent manner, without inducing any marked change in current kinetics. The toxin was more effective in blocking K+ than Na+ channels. P-CTX-4B shifted the voltage-dependence of Na+ conductance by about 14 mV towards more negative membrane potentials. This effect was reversed by increasing Ca2+ in the external solution. A negative shift of about 16 mV in the steady-state Na+ inactivation-voltage curve was also observed in the presence of the toxin. Unmodified and P-CTX-4B-modified Na+ currents were similarly affected by the local anaesthetic lidocaine. The decrease of the two currents by lidocaine was dependent on both the concentration and the membrane potential during pre-pulses. In conclusion, P-CTX-4B appears about four times more effective than P-CTX-1B to affect K+ channels, whereas it is about 50 times less efficient to affect Na+ channels of axonal membranes. These actions may be related to subtle differences between the two chemical structures of molecules. 相似文献
7.
Julie K. Klint Géza Berecki Thomas Durek Mehdi Mobli Oliver Knapp Glenn F. King David J. Adams Paul F. Alewood Lachlan D. Rash 《Biochemical pharmacology》2014
Spider venoms are replete with peptidic ion channel modulators, often with novel subtype selectivity, making them a rich source of pharmacological tools and drug leads. In a search for subtype-selective blockers of voltage-gated calcium (CaV) channels, we isolated and characterized a novel 39-residue peptide, ω-TRTX-Cc1a (Cc1a), from the venom of the tarantula Citharischius crawshayi (now Pelinobius muticus). Cc1a is 67% identical to the spider toxin ω-TRTX-Hg1a, an inhibitor of CaV2.3 channels. We assembled Cc1a using a combination of Boc solid-phase peptide synthesis and native chemical ligation. Oxidative folding yielded two stable, slowly interconverting isomers. Cc1a preferentially inhibited Ba2+ currents (IBa) mediated by L-type (CaV1.2 and CaV1.3) CaV channels heterologously expressed in Xenopus oocytes, with half-maximal inhibitory concentration (IC50) values of 825 nM and 2.24 μM, respectively. In rat dorsal root ganglion neurons, Cc1a inhibited IBa mediated by high voltage-activated CaV channels but did not affect low voltage-activated T-type CaV channels. Cc1a exhibited weak activity at NaV1.5 and NaV1.7 voltage-gated sodium (NaV) channels stably expressed in mammalian HEK or CHO cells, respectively. Experiments with modified Cc1a peptides, truncated at the N-terminus (ΔG1–E5) or C-terminus (ΔW35–V39), demonstrated that the N- and C-termini are important for voltage-gated ion channel modulation. We conclude that Cc1a represents a novel pharmacological tool for probing the structure and function of L-type CaV channels. 相似文献
8.
Wan Wan Lin, C. Y. Lee and J. W. Burnett. Effect of sea nettle (Chrysaora quinquecirrha) venom on isolated rat aorta. Toxicon26, 1209–1212, 1988.—The venom from sea nettle (Chrysaora quinquecirrha) (1–10μg/ml) produced an irreversible contraction of the isolated rat aortic ring that was slow in onset, increased with time, and reached maximum in about 10–20 min. The contraction was not inhibited by pretreatment with phenoxybenzamine, atropine, indomethacin, tetrodotoxin, ouabain, low Na+ or Na+-free medium, however, it was markedly decreased by the Ca2+ channel blockers, nifedipine and verapamil. In Ca2+-free medium, no increase in tension was produced by the venom. It is concluded that sea nettle venom causes a contraction of the rat aortic ring by increasing Ca2+ influx through the voltage-dependent Ca2+ channels. 相似文献
9.
Alexander I Bondarenko Konstantin Drachuk Olga Panasiuk Vadim Sagach Andras T Deak Roland Malli Wolfgang F Graier 《British journal of pharmacology》2013,169(4):933-948
Background and Purpose
N-arachidonoyl glycine (NAGly) is a lipoamino acid with vasorelaxant properties. We aimed to explore the mechanisms of NAGly''s action on unstimulated and agonist-stimulated endothelial cells.Experimental Approach
The effects of NAGly on endothelial electrical signalling were studied in combination with vascular reactivity.Key Results
In EA.hy926 cells, the sustained hyperpolarization to histamine was inhibited by the non-selective Na+/Ca2+ exchanger (NCX) inhibitor bepridil and by an inhibitor of reversed mode NCX, KB-R7943. In cells dialysed with Cs+-based Na+-containing solution, the outwardly rectifying current with typical characteristics of NCX was augmented following histamine exposure, further increased upon external Na+ withdrawal and inhibited by bepridil. NAGly (0.3–30 μM) suppressed NCX currents in a URB597- and guanosine 5′-O-(2-thiodiphosphate) (GDPβS)-insensitive manner, [Ca2+]i elevation evoked by Na+ removal and the hyperpolarization to histamine. In rat aorta, NAGly opposed the endothelial hyperpolarization and relaxation response to ACh. In unstimulated EA.hy926 cells, NAGly potentiated the whole-cell current attributable to large-conductance Ca2+-activated K+ (BKCa) channels in a GDPβS-insensitive, paxilline-sensitive manner and produced a sustained hyperpolarization. In cell-free inside-out patches, NAGly stimulated single BKCa channel activity.Conclusion and Implications
Our data showed that NCX is a Ca2+ entry pathway in endothelial cells and that NAGly is a potent G-protein-independent modulator of endothelial electrical signalling and has a dual effect on endothelial electrical responses. In agonist pre-stimulated cells, NAGly opposes hyperpolarization and relaxation via inhibition of NCX-mediated Ca2+ entry, while in unstimulated cells, it promotes hyperpolarization via receptor-independent activation of BKCa channels. 相似文献10.
Pengfei Huang Yiya Zhang Xinyi Chen Li Zhu Dazhong Yin Xiongzhi Zeng Songping Liang 《Toxins》2014,6(8):2568-2579
Intermediate-conductance Ca2+-activated K+ (IK) channels are calcium/calmodulin-regulated voltage-independent K+ channels. Activation of IK currents is important in vessel and respiratory tissues, rendering the channels potential drug targets. A variety of small organic molecules have been synthesized and found to be potent activators of IK channels. However, the poor selectivity of these molecules limits their therapeutic value. Venom-derived peptides usually block their targets with high specificity. Therefore, we searched for novel peptide activators of IK channels by testing a series of toxins from spiders. Using electrophysiological experiments, we identified hainantoxin-I (HNTX-I) as an IK-channel activator. HNTX-I has little effect on voltage-gated Na+ and Ca2+ channels from rat dorsal root ganglion neurons and on the heterologous expression of voltage-gated rapidly activating delayed rectifier K+ channels (human ether-à-go-go-related gene; human ERG) in HEK293T cells. Only 35.2% ± 0.4% of the currents were activated in SK channels, and there was no effect on BK channels. We demonstrated that HNTX-I was not a phrenic nerve conduction blocker or acutely toxic. This is believed to be the first report of a peptide activator effect on IK channels. Our study suggests that the activity and selectivity of HNTX-I on IK channels make HNTX-I a promising template for designing new drugs for cardiovascular diseases. 相似文献
11.
Hui Chen Dong Zhang Sheng-ping Chao Jiang-hua Ren Lin Xu Xue-jun Jiang Shi-min Wang 《Acta pharmacologica Sinica》2013,34(2):221-230
Aim:
To study the effects of Na+ channel blocker flecainide and L-type Ca2+ channel antagonist verapamil on the voltage-gated fKv1.4ΔN channel, an N-terminal-deleted mutant of the ferret Kv1.4 K+ channel.Methods:
fKv1.4ΔN channels were stably expressed in Xenopus oocytes. The K+ currents were recorded using a two-electrode voltage-clamp technique. The drugs were administered through superfusion.Results:
fKv1.4ΔN currents displayed slow inactivation, with a half-inactivation potential of −41.74 mV and a slow recovery from inactivation (τ=1.90 s at −90 mV). Flecainide and verapamil blocked the currents with IC50 values of 512.29±56.92 and 260.71±18.50 μmol/L, respectively. The blocking action of the drugs showed opposite voltage-dependence: it was enhanced with depolarization for flecainide, and was attenuated with depolarization for verapamil. Both the drugs exerted state-dependent blockade on fKv1.4ΔN currents, but verapamil showed a stronger use-dependent blockage compared with flecainide. Flecainide accelerated the C-type inactivation rate without affecting the recovery kinetics and the steady-state activation. Verapamil also accelerated the inactivation kinetics of the currents, but unlike flecainide, it affected both the recovery and the steady-state activation, causing slower recovery of fKv1.4ΔN channel and a depolarizing shift of the steady-state activation curve.Conclusion:
The results demonstrate that widely used antiarrhythmic drugs flecainide and verapamil substantially inhibit fKv1.4ΔN channels expressed in Xenopus oocytes by binding to the open state of the channels. Therefore, caution should be taken when these drugs are administered in combination with K+ channel blockers to treat arrhythmia. 相似文献12.
13.
Brown recluse spider (Loxosceles reclusa) venom toxin causes death but no necrosis in mice. Six hours after challenge with toxin isolated from venom apparatus extract, mice show elevations of a number of serum enzyme activities indicating damage to the liver and possibly to other tissues including those of the kidney, heart and central nervous system. No obvious changes were apparent in plasma Na+, K+ and Ca2+ concentrations after venom challenge. The hematocrit of venom-challenged animals was not significantly different from controls. Plasma glucose decreased slightly. Urine K+ and Ca2+ concentration increased while Na+ decreased. No evidence for in vivo hemolysis was observed, although the venom did cause in vitro hemolysis of mouse erythrocytes. 相似文献
14.
Martentoxin (MarTX), a 37-residue peptide purified from the venom of East-Asian scorpion (Buthus martensi Karsch), was capable of blocking large-conductance Ca2+-activated K+ (BK) channels. Here, we report an effective expression and purification approach for this toxin. The cDNA encoding martentoxin was expressed by the prokaryotic expression system pGEX-4T-3 which was added an enterokinase cleavage site by PCR. The fusion protein (GST-rMarTX) was digested by enterokinase to release hetero-expressed toxin and further purified via reverse-phase HPLC. The molecular weight of the hetero-expressed rMarTX was 4059.06 Da, which is identical to that of the natural peptide isolated from scorpion venom. Functional characterization through whole-cell patch clamp showed that rMarTX selectively and potently inhibited the currents of neuronal BK channels (α + β4) (IC50 = 186 nM), partly inhibited mKv1.3, but hardly having any significant effect on hKv4.2 and hKv3.1a even at 10 μM. Successful expression of martentoxin lays basis for further studies of structure-function relationship underlying martentoxin or other potassium-channel specific blockers. 相似文献
15.
Background and purpose:
Recent pharmacological studies have proposed there is a high degree of similarity between calcium-activated Cl− channels (CaCCs) and large conductance, calcium-gated K+ channels (KCa1.1). The goal of the present study was to ascertain whether blockers of KCa1.1 inhibited calcium-activated Cl− currents (IClCa) and if the pharmacological overlap between KCa1.1 and CaCCs extends to intermediate and small conductance, calcium-activated K+ channels.Experimental approaches:
Whole-cell Cl− and K+ currents were recorded from murine portal vein myocytes using the whole-cell variant of the patch clamp technique. CaCC currents were evoked by pipette solutions containing 500 nM free [Ca2+].Key results:
The selective KCa1.1 blocker paxilline (1 µM) inhibited IClCa by ∼90%, whereas penitrem A (1 µM) and iberiotoxin (100 and 300 nM) reduced the amplitude of IClCa by ∼20%, as well as slowing channel deactivation. Paxilline also abolished the stimulatory effect of niflumic acid on the CaCC. In contrast, an antibody against the Ca2+-binding domain of murine KCa1.1 had no effect on IClCa while inhibiting spontaneous KCa1.1 currents. Structurally different modulators of small and intermediate conductance calcium-activated K+ channels (KCa2.1 and KCa2.3), namely 1-EBIO, (100 µM); NS309, (1 µM); TRAM-34, (10 µM); UCL 1684, (1 µM) had no effect on IClCa.Conclusions and implications:
These data show that the selective KCa1.1 blockers also reduce IClCa considerably. However, the pharmacological overlap that exists between CaCCs and KCa1.1 does not extend to the calcium-binding domain or to other calcium-gated K+ channels. 相似文献16.
The effects of scorpion toxin (STX) on both spontaneous and evoked glycinergic and glutamatergic postsynaptic currents were studied by using both the mechanically dissociated single SDCN neuron (synaptic bouton preparation) and the ‘focal electrical stimulation technique’. In the experimental condition where Na+ channels on postsynaptic soma membrane were blocked by intracellular perfusion of QX-314, STX increased dose-dependently the frequency of spontaneous glycinergic and glutamatergic postsynaptic currents (sIPSC and sEPSC, respectively) without affecting the amplitude, suggesting STX acts on inhibitory and excitatory presynaptic nerve terminal. Such a facilitatory effect of STX on sIPSC was stronger than that on sEPSC. On the other hand, STX significantly enhanced the averaged current amplitude and decreased the failure rate (Rf) of both evoked inhibitory and excitatory postsynaptic currents (eIPSC and eEPSC, respectively), indicating that STX increases not only the release frequency of glycine and glutamate but also the amount of their release from the both presynaptic nerve endings. These effects of STX were completely removed by adding Na+ or Ca2+ channel blockers, indicating that STX increases Ca2+ influx through Ca2+ channels triggered by activating voltage-dependent Na+ channels on the nerve terminals. In addition, the difference of STX actions on the amplitude of spontaneous and evoked currents was discussed. 相似文献
17.
Oleg V. Yarishkin Eun Mi Hwang Donggyu Kim Jae Cheal Yoo Sang Soo Kang Deok Ryoung Kim Jae-Hee-Jung Shin Hye-Joo Chung Ho-Sang Jeong Dawon Kang Jaehee Han Jae-Yong Park Seong-Geun Hong 《The Korean journal of physiology & pharmacology》2009,13(6):437-442
A non-steroidal anti-inflammatory drug (NSAID) has many adverse effects including cardiovascular (CV) risk. Diclofenac among the nonselective NSAIDs has the highest CV risk such as congestive heart failure, which resulted commonly from the impaired cardiac pumping due to a disrupted excitation-contraction (E-C) coupling. We investigated the effects of diclofenac on the L-type calcium channels which are essential to the E-C coupling at the level of single ventricular myocytes isolated from neonatal rat heart, using the whole-cell voltage-clamp technique. Only diclofenac of three NSAIDs, including naproxen and ibuprofen, significantly reduced inward whole cell currents. At concentrations higher than 3 µM, diclofenac inhibited reversibly the Na+ current and did irreversibly the L-type Ca2+ channels-mediated inward current (IC50=12.89±0.43 µM) in a dose-dependent manner. However, nifedipine, a well-known L-type channel blocker, effectively inhibited the L-type Ca2+ currents but not the Na+ current. Our finding may explain that diclofenac causes the CV risk by the inhibition of L-type Ca2+ channel, leading to the impairment of E-C coupling in cardiac myocytes. 相似文献
18.
Aim:
Atazanavir (ATV) is a HIV-1 protease inhibitor for the treatment of AIDS patients, which is recently reported to provoke excessive prolongation of the QT interval and torsades de pointes (TdP). In order to elucidate its arrhythmogenic mechanisms, we investigated the effects of ATV on the hERG K+ channels expressed in HEK293 cells.Methods:
hERG K+ currents were detected using whole-cell patch clamp recording in HEK293 cells transfected with EGFP-hERG plasmids. The expression of hERG protein was measured with Western blotting. Two mutants (Y652A and F656C) were constructed in the S6 domain within the inner helices of hERG K+ channels that were responsible for binding of various drugs. The trafficking of hERG protein was studied with confocal microscopy.Results:
Application of ATV (0.01–30 μmol/L) concentration-dependently decreased hERG K+ currents with an IC50 of 5.7±1.8 μmol/L. ATV (10 μmol/L) did not affect the activation and steady-state inactivation of hERG K+ currents. Compared with the wild type hERG K+ channels, both Y652A and F656C mutants significantly reduced the inhibition of ATV on hERG K+ currents. Overnight treatment with ATV (0.1–30 μmol/L) concentration-dependently reduced the amount of fully glycosylated 155 kDa hERG protein without significantly affecting the core-glycosylated 135 kDa hERG protein in the cells expressing the WT-hERG protein. Confocal microscopy studies confirmed that overnight treatment with ATV obstructed the trafficking of hERG protein to the cell membrane.Conclusion:
ATV directly blocks hERG K+ channels via binding to the residues Y652 and F656 in the S6 domain, and indirectly obstructs the transport of the hERG protein to the cell membrane. 相似文献19.
Miroslav Radenkovi? Marko Stojanovi? Neboj?a Skorupan Milica Prostran 《Scientia pharmaceutica》2013,81(3):749-761
Bradykinin (BK) plays an important role in different physiological processes including the general preservation and modulation of vascular systems. The present study was designed in order to examine the effect of BK on isolated rat femoral artery rings and to investigate the participation of intact endothelium, cyclooxygenase products, Ca2+ channels, Na+/K+–ATPase, and B2 kinin receptors in BK-induced action. Circular artery segments were placed in organ baths. The endothelium was mechanically removed from some arteries. Concentration–contraction curves for BK were obtained in the rings previously equilibrated at the basal tone. BK produced a concentration–dependent contraction, which was reduced by endothelial denudation. The BK–induced effect was almost completely inhibited by indomethacin (cyclooxygenase inhibitor) or OKY–046 (thromboxane A2–synthase inhibitor). Nifedipine (Ca2+ channel blocker), ouabain (Na+/K+–ATPase inhibitor), or HOE–140 (selective B2 kinin receptor antagonist) significantly reduced the BK–evoked effect. In conclusion, it can be proposed that BK produces concentration– and endothelium–dependent contractions of the isolated rat femoral artery, which is for the most part a consequence of B2 kinin receptor activation. Cyclooxygenase contractile products, especially thromboxane A2, play a significant role in this course of action. The transduction mechanism involved in the process of BK–induced femoral artery contraction include the activation of voltage–gated Ca2+ channels, and in a smaller extent Na+/K+–ATPase as well. 相似文献
20.
HT Syyong HHC Yang G Trinh C Cheung KH Kuo C van Breemen 《British journal of pharmacology》2009,156(4):587-600