The complement membrane attack complex and the bystander effect in cerebral vasospasm

1997 ◽  
Vol 3 (4) ◽  
pp. E7
Author(s):  
Charles C. Park ◽  
Moon L. Shin ◽  
J. Marc Simard
Keyword(s):  
Smooth Muscle ◽  
Cerebral Vasospasm ◽  
Complement Activation ◽  
Bystander Effect ◽  
Cell Damage ◽  
Membrane Attack Complex ◽  
Membrane Conductance ◽  
Autologous Serum ◽  
Innocent Bystander ◽  
Patch Clamp Technique

Activation of complement results in formation of membrane attack complexes (MACs) that can insert themselves either into cells that initiate complement activation or into nearby (“innocent bystander”) cells. The MACs form large-conductance, nonspecific ion channels that can cause lytic or sublytic cell damage. The authors used a highly sensitive patch clamp technique to assess the contribution of the bystander effect to the pathophysiology of cerebral vasospasm. They compared the effect of complement activation by autologous aged versus fresh erythrocytes on the membrane conductance of freshly isolated rat cerebral artery smooth-muscle cells. In the presence of autologous serum, aged, but not fresh, erythrocytes caused a large increase in membrane conductance, an effect that was prevented by heat-inactivating the serum. Ethyleneglycol tetraacetic acid in the presence of Mg++ attenuated the effect, indicating that complement activation was taking place via the classic pathway. The effect was reproduced by zymosan-activated autologous serum, suggesting that such changes in conductance could result from insertion of MACs secondary to a bystander effect. Both C8- and C9-depleted heterologous sera produced minimal effects that were converted to full effect by addition of the missing complement component. Superoxide dismutase plus catalase did not attenuate the conductance changes produced by autologous serum plus aged erythrocytes. Autologous serum plus aged erythrocyte membrane ghosts that were free of lysate caused a typical increase in conductance. This study demonstrates that complement activation by aged erythrocytes can result in MAC insertion into innocent bystander smooth-muscle cell membranes and that this mechanism, heretofore undescribed, may contribute to development of vasospasm after subarachnoid hemorrhage.

The complement membrane attack complex and the bystander effect in cerebral vasospasm

1997 ◽  
Vol 87 (2) ◽  
pp. 294-300 ◽  
Author(s):  
Charles C. Park ◽  
Moon L. Shin ◽  
J. Marc Simard
Keyword(s):  
Smooth Muscle ◽  
Cerebral Vasospasm ◽  
Complement Activation ◽  
Bystander Effect ◽  
Cell Damage ◽  
Membrane Conductance ◽  
Autologous Serum ◽  
Innocent Bystander ◽  
Patch Clamp Technique ◽  
Content Type

✓ Activation of complement results in formation of membrane attack complexes (MACs) that can insert themselves either into cells that initiate complement activation or into nearby (“innocent bystander”) cells. The MACs form large-conductance, nonspecific ion channels that can cause lytic or sublytic cell damage. The authors used a highly sensitive patch clamp technique to assess the contribution of the bystander effect to the pathophysiology of cerebral vasospasm. They compared the effect of complement activation by autologous aged versus fresh erythrocytes on the membrane conductance of freshly isolated rat cerebral artery smooth-muscle cells. In the presence of autologous serum aged, but not fresh, erythrocytes caused a large increase in membrane conductance, an effect that was prevented by heat-inactivating the serum. Ethyleneglycol tetraacetic acid in the presence of Mg++ attenuated the effect, indicating that complement activation was taking place via the classic pathway. The effect was reproduced by zymosan-activated autologous serum, suggesting that such changes in conductance could result from insertion of MACs secondary to a bystander effect. Both C8- and C9-depleted heterologous sera produced minimal effects that were converted to full effect by addition of the missing complement component. Superoxide dismutase plus catalase did not attenuate the conductance changes produced by autologous serum plus aged erythrocytes. Autologous serum plus aged erythrocyte membrane ghosts that were free of lysate caused a typical increase in conductance. This study demonstrates that complement activation by aged erythrocytes can result in MAC insertion into innocent bystander smooth-muscle cell membranes and that this mechanism, heretofore undescribed, may contribute to development of vasospasm after subarachnoid hemorrhage.

scholarly journals Extracellular Vesicle-Induced Classical Complement Activation Leads to Retinal Endothelial Cell Damage via MAC Deposition

2020 ◽  
Vol 21 (5) ◽  
pp. 1693 ◽  
Author(s):  
Chao Huang ◽  
Kiera P. Fisher ◽  
Sandra S. Hammer ◽  
Julia V. Busik
Keyword(s):  
Extracellular Vesicles ◽  
Complement Activation ◽  
Cell Damage ◽  
Membrane Attack Complex ◽  
Extracellular Vesicle ◽  
Rat Plasma ◽  
Classical Complement Pathway ◽  
Endothelium Damage ◽  
Classical Complement

Several studies have suggested that there is a link between membrane attack complex (MAC) deposition in the retina and the progression of diabetic retinopathy (DR). Our recent investigation demonstrated that circulating IgG-laden extracellular vesicles contribute to an increase in retinal vascular permeability in DR through activation of the complement system. However, the mechanism through which extracellular vesicle-induced complement activation contributes to retinal vascular cytolytic damage in DR is not well understood. In this study, we demonstrate that IgG-laden extracellular vesicles in rat plasma activate the classical complement pathway, and in vitro Streptozotocin (STZ)-induced rat diabetic plasma results in MAC deposition and cytolytic damage in human retinal endothelial cells (HRECs). Moreover, removal of the plasma extracellular vesicles reduced the MAC deposition and abrogated cytolytic damage seen in HRECs. Together, the results of this study demonstrate that complement activation by IgG-laden extracellular vesicles in plasma could lead to MAC deposition and contribute to endothelium damage and progression of DR.

scholarly journals Consecutive enzyme cascades: complement activation at the cell surface triggers increased tissue factor activity

Blood ◽  
1990 ◽  
Vol 76 (2) ◽  
pp. 361-367 ◽  
Author(s):  
SD Carson ◽  
DR Johnson
Keyword(s):  
Cell Surface ◽  
Tissue Factor ◽  
Complement Activation ◽  
Cell Damage ◽  
Membrane Attack Complex ◽  
Fibrin Clot ◽  
Coagulation Cascade ◽  
Factor Activity ◽  
Physical Damage ◽  
Tissue Factor Activity

Abstract Complement activation at the cell surface initiates cell damage through a series of reactions occurring at the cell membrane and, after assembly of the terminal membrane attack complex, produces leakage of cytoplasmic contents from the cell. It has been documented that chemical or physical damage to cell membranes can cause a rapid increase in the expression of tissue factor procoagulant activity. In this study, antibody-mediated complement activation at the cell surface resulted in increased tissue factor activity, which correlated with cytolysis, as measured by 51-chromium release. Therefore, complement fixation on the cell surface can have a direct and immediate stimulatory effect on the coagulation cascade at the point of its initiation, with formation of a fibrin clot requiring only three consecutive proteolytic reactions after immunologically mediated cell damage.

scholarly journals Consecutive enzyme cascades: complement activation at the cell surface triggers increased tissue factor activity

Blood ◽  
1990 ◽  
Vol 76 (2) ◽  
pp. 361-367
Author(s):  
SD Carson ◽  
DR Johnson
Keyword(s):  
Cell Surface ◽  
Tissue Factor ◽  
Complement Activation ◽  
Cell Damage ◽  
Membrane Attack Complex ◽  
Fibrin Clot ◽  
Coagulation Cascade ◽  
Factor Activity ◽  
Physical Damage ◽  
Tissue Factor Activity

Complement activation at the cell surface initiates cell damage through a series of reactions occurring at the cell membrane and, after assembly of the terminal membrane attack complex, produces leakage of cytoplasmic contents from the cell. It has been documented that chemical or physical damage to cell membranes can cause a rapid increase in the expression of tissue factor procoagulant activity. In this study, antibody-mediated complement activation at the cell surface resulted in increased tissue factor activity, which correlated with cytolysis, as measured by 51-chromium release. Therefore, complement fixation on the cell surface can have a direct and immediate stimulatory effect on the coagulation cascade at the point of its initiation, with formation of a fibrin clot requiring only three consecutive proteolytic reactions after immunologically mediated cell damage.

Electron Probe Analysis of Vertebrate Smooth Muscle: Distribution of Ca and Ci

1976 ◽  
Vol 34 ◽  
pp. 334-335 ◽  
Author(s):  
Avril V. Somlyo ◽  
H. Shuman ◽  
A.P. Somlyo
Keyword(s):  
Smooth Muscle ◽  
Electron Probe ◽  
Preliminary Report ◽  
Cell Damage ◽  
Electron Probe Analysis ◽  
Perinuclear Space ◽  
Probe Analysis ◽  
High K ◽  
Low K ◽  
Initial Results

This is a preliminary report of electron probe analysis of rabbit portal-anterior mesenteric vein (PAMV) smooth muscle cryosectioned without fixation or cryoprotection. The instrumentation and method of electron probe quantitation used (1) and our initial results with cardiac (2) and skeletal (3) muscle have been presented elsewhere.In preparations depolarized with high K (K2SO4) solution, significant calcium peaks were detected over the sarcoplasmic reticulum (Fig 1 and 2) and the continuous perinuclear space. In some of the fibers there were also significant (up to 200 mM/kg dry wt) calcium peaks over the mitochondria. However, in smooth muscle that was not depolarized, high mitochondrial Ca was found in fibers that also contained elevated Na and low K (Fig 3). Therefore, the possibility that these Ca-loaded mitochondria are indicative of cell damage remains to be ruled out.

Nitric oxide mediates outward potassium currents in opossum esophageal circular smooth muscle

1996 ◽  
Vol 270 (6) ◽  
pp. G932-G938 ◽  
Author(s):  
J. Jury ◽  
K. R. Boev ◽  
E. E. Daniel
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Circular Muscle ◽  
Outward Current ◽  
Equilibrium Potential ◽  
Patch Clamp Technique ◽  
Pipette Solution ◽  
Whole Cell ◽  
Circular Smooth Muscle ◽  
Outward Currents

Single smooth muscle cells from the opossum body circular muscle were isolated and whole cell currents were characterized by the whole cell patch-clamp technique. When the cells were held at -50 mV and depolarized to 70 mV in 20-mV increments, initial small inactivating inward currents were evoked (-30 to 30 mV) followed by larger sustained outward currents. Depolarization from a holding potential of -90 mV evoked an initial fast inactivating outward current sensitive to 4-aminopyridine but not to high levels of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). The outward currents reversed near K+ equilibrium potential and were abolished when KCl was replaced by CsCl in the pipette solution. The sustained outward current was inhibited by quinine and cesium. High EGTA in the pipette solution reduced but did not abolish the sustained outward currents, suggesting that both Ca(2+)-dependent and -independent currents were evoked. The nitric oxide (NO)-releasing agents Sin-1 and sodium nitroprusside increased outward K+ currents. High levels of EGTA in the pipette solution abolished the increase in outward current induced by Sin-1. The presence of cyclopiazonic acid, an inhibitor of the sarcoplasmic reticulum (SR) Ca2+ pump, blocked the effects of NO-releasing agents. We conclude that NO release activates K+ outward currents in opossum esophagus circular muscle, which may depend on Ca2+ release from the SR stores.

scholarly journals Membrane Currents in Airway Smooth Muscle: Mechanisms and Therapeutic Implications

1997 ◽  
Vol 4 (1) ◽  
pp. 13-20
Author(s):  
Luke J Janssen
Keyword(s):  
Smooth Muscle ◽  
Ion Channels ◽  
Calcium Channels ◽  
Airway Smooth Muscle ◽  
Calcium Ion ◽  
Membrane Conductance ◽  
Chloride Ion ◽  
Potassium Ion Channels ◽  
Therapeutic Implications ◽  
Transient Activation

Electrophysiological and pharmacological techniques were used to characterize the membrane conductance changes underlying spasmogen-evoked depolarization in airway smooth muscle (ASM). Changes included a transient activation of chloride ion channels and prolonged suppression of potassium ion channels; both changes are triggered by release of internally sequestered calcium ion and in turn cause opening of voltage-dependent calcium channels. The resultant influx of calcium ions contributes to contraction as well as to refilling of the internal calcium ion pool. Bronchodilators, on the other hand, act in part through activation of potassium channels, with consequent closure of calcium channels. The tools used to study ion channels in ASM are described, and the investigations of the roles of ion channels in ASM physiology (autacoid-evoked depolarization and hyperpolarization) and pathophysiology (airway hyperresponsiveness) are summarized. Finally, how the relationship between ion channels and ASM function/dysfunction may relate to the treatment of asthma and related breathing disorders is discussed.

scholarly journals Ca2+-activated Cl− current in sheep lymphatic smooth muscle

2000 ◽  
Vol 279 (5) ◽  
pp. C1327-C1335 ◽  
Author(s):  
H. M. Toland ◽  
K. D. McCloskey ◽  
K. D. Thornbury ◽  
N. G. McHale ◽  
M. A. Hollywood
Keyword(s):  
Smooth Muscle ◽  
Carboxylic Acid ◽  
Patch Clamp ◽  
Action Potentials ◽  
Channel Blocker ◽  
Equilibrium Potential ◽  
Plateau Phase ◽  
Current Clamp ◽  
Patch Clamp Technique ◽  
Perforated Patch Clamp

Freshly dispersed sheep mesenteric lymphatic smooth muscle cells were studied at 37°C using the perforated patch-clamp technique with Cs+- and K+-filled pipettes. Depolarizing steps evoked currents that consisted ofl-type Ca2+ [ I Ca(L)] current and a slowly developing current. The slow current reversed at 1 ± 1.5 mV with symmetrical Cl− concentrations compared with 23.2 ± 1.2 mV ( n = 5) and −34.3 ± 3.5 mV ( n = 4) when external Cl− was substituted with either glutamate (86 mM) or I− (125 mM). Nifedipine (1 μM) blocked and BAY K 8644 enhanced I Ca(L), the slow-developing sustained current, and the tail current. The Cl− channel blocker anthracene-9-carboxylic acid (9-AC) reduced only the slowly developing inward and tail currents. Application of caffeine (10 mM) to voltage-clamped cells evoked currents that reversed close to the Cl− equilibrium potential and were sensitive to 9-AC. Small spontaneous transient depolarizations and larger action potentials were observed in current clamp, and these were blocked by 9-AC. Evoked action potentials were triphasic and had a prominent plateau phase that was selectively blocked by 9-AC. Similarly, fluid output was reduced by 9-AC in doubly cannulated segments of spontaneously pumping sheep lymphatics, suggesting that the Ca2+-activated Cl− current plays an important role in the electrical activity underlying spontaneous activity in this tissue.

Mitochondrial calcium overload triggers complement-dependent superoxide-mediated programmed cell death in Trypanosoma cruzi

2009 ◽  
Vol 418 (3) ◽  
pp. 595-604 ◽  
Author(s):  
Florencia Irigoín ◽  
Natalia M. Inada ◽  
Mariana P. Fernandes ◽  
Lucía Piacenza ◽  
Fernanda R. Gadelha ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Trypanosoma Cruzi ◽  
Complement Activation ◽  
Superoxide Radical ◽  
Membrane Attack Complex ◽  
Cell Respiration ◽  
Mitochondrial Uncoupling ◽  
O2 Production ◽  
Complement Deposition

The epimastigote stage of Trypanosoma cruzi undergoes PCD (programmed cell death) when exposed to FHS (fresh human serum). Although it has been known for over 30 years that complement is responsible for FHS-induced death, the link between complement activation and triggering of PCD has not been established. We have previously shown that the mitochondrion participates in the orchestration of PCD in this model. Several changes in mitochondrial function were described, and in particular it was shown that mitochondrion-derived O2•− (superoxide radical) is necessary for PCD. In the present study, we establish mitochondrial Ca2+ overload as the link between complement deposition and the observed changes in mitochondrial physiology and the triggering of PCD. We show that complement activation ends with the assembly of the MAC (membrane attack complex), which allows influx of Ca2+ and release of respiratory substrates to the medium. Direct consequences of these events are accumulation of Ca2+ in the mitochondrion and decrease in cell respiration. Mitochondrial Ca2+ causes partial dissipation of the inner membrane potential and consequent mitochondrial uncoupling. Moreover, we provide evidence that mitochondrial Ca2+ overload is responsible for the increased O2•− production, and that if cytosolic Ca2+ rise is not accompanied by the accumulation of the cation in the mitochondrion and consequent production of O2•−, epimastigotes die by necrosis instead of PCD. Thus our results suggest a model in which MAC assembly on the parasite surface allows Ca2+ entry and its accumulation in the mitochondrion, leading to O2•− production, which in turn constitutes a PCD signal.

BICUCULLINE/BACLOFEN-INSENSITIVE GABA RESPONSE IN CRUSTACEAN NEURONES IN CULTURE

1994 ◽  
Vol 191 (1) ◽  
pp. 167-193
Author(s):  
C Jackel ◽  
W Krenz ◽  
F Nagy
Keyword(s):  
Reversal Potential ◽  
Membrane Conductance ◽  
Gamma Aminobutyric Acid ◽  
Action Potential Firing ◽  
Patch Clamp Technique ◽  
Conformationally Restricted ◽  
Whole Cell Patch Clamp ◽  
Gabac Receptor ◽  
Potential Firing ◽  
Sr 95531

Neurones were dissociated from thoracic ganglia of embryonic and adult lobsters and kept in primary culture. When gamma-aminobutyric acid (GABA) was applied by pressure ejection, depolarizing or hyperpolarizing responses were produced, depending on the membrane potential. They were accompanied by an increase in membrane conductance. When they were present, action potential firing was inhibited. The pharmacological profile and ionic mechanism of GABA-evoked current were investigated under voltage-clamp with the whole-cell patch-clamp technique. The reversal potential of GABA-evoked current depended on the intracellular and extracellular Cl- concentration but not on extracellular Na+ and K+. Blockade of Ca2+ channels by Mn2+ was also without effect. The GABA-evoked current was mimicked by application of the GABAA agonists muscimol and isoguvacine with an order of potency muscimol>GABA>isoguvacine. cis-4-aminocrotonic acid (CACA), a folded and conformationally restricted GABA analogue, supposed to be diagnostic for the vertebrate GABAC receptor, also induced a bicuculline-resistant chloride current, although with a potency about 10 times lower than that of GABA. The GABA-evoked current was largely blocked by picrotoxin, but was insensitive to the GABAA antagonists bicuculline, bicuculline methiodide and SR 95531 at concentrations of up to 100 µmol l-1. Diazepam and phenobarbital did not exert modulatory effects. The GABAB antagonist phaclophen did not affect the GABA-induced current, while the GABAB agonists baclophen and 3-aminopropylphosphonic acid (3-APA) never evoked any response. Our results suggest that lobster thoracic neurones in culture express a chloride-conducting GABA-receptor channel which conforms to neither the GABAA nor the GABAB types of vertebrates but shows a pharmacology close to that of the novel GABAC receptor described in the vertebrate retina.

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