Prevention of vasospasm by anti-CD11/CD18 monoclonal antibody therapy following subarachnoid hemorrhage in rabbits

2004 ◽  
Vol 101 (1) ◽  
pp. 88-92 ◽  
Author(s):  
Gustavo Pradilla ◽  
Paul P. Wang ◽  
Federico G. Legnani ◽  
Lynn Ogata ◽  
Gregory N. Dietsch ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Endothelial Cells ◽  
Subarachnoid Hemorrhage ◽  
Autologous Blood ◽  
Rabbit Model ◽  
Control Group ◽  
Lymphocyte Function ◽  
Content Type ◽  
Basilar Arteries ◽  
Fine Print

Object. Adhesion of leukocytes and their migration into the periadventitial space may be critical in the pathophysiology of vasospasm following subarachnoid hemorrhage (SAH). The cell adhesion molecules involved in this process are lymphocyte function—associated antigen—1 (CD11a/CD18) and macrophage antigen—1 (CD11b/CD18), which are present on neutrophils/macrophages, and intercellular adhesion molecule—1 (CD54), which is present in endothelial cells. A humanized monoclonal antibody (mAb), Hu23F2G, targets CD11/CD18 and prevents leukocyte adhesion to endothelial cells. In this study, systemic administration of Hu23F2G prevented vasospasm in the rabbit model of SAH. Methods. Twenty-six New Zealand White rabbits were injected with autologous blood into the cisterna magna to induce SAH, after which they were randomized to receive injections of either Hu23F2G (10 animals) or a placebo at 30 minutes and 24 and 48 hours after SAH (six animals). Control animals underwent sham operations (four animals) or SAH alone (six animals). The animals were killed 72 hours after SAH, their bodies perfused and fixed, and their basilar arteries processed for morphometric analysis. Peripheral white blood cells (WBCs) were counted at 72 hours. The percentages of lumen patency were compared using the Student t-test. The presence of neutrophils and macrophages was confirmed by immunohistochemical analysis in which a rat anti—rabbit anti-CD18 mAb and cresyl violet were used. Treatment with Hu23F2G resulted in the significant prevention of vasospasm. Animals treated with Hu23F2G had 90 ± 7% lumen patency compared with 65 ± 7% in the placebo group (p = 0.025). The percentage of lumen patency in the SAH-only group was 59 ± 10%. The mean WBC count was 16,300 ± 2710/µl in the treatment group, compared with 7000 ± 386/µl in the control group (p = 0.02). Administration of Hu23F2G produced increased numbers of WBCs in 70% of the animals treated. Conclusions. This study supports the concept that leukocyte—endothelial cell interactions play an important role in the pathophysiology of chronic vasospasm after SAH. Systemic therapy with an anti-CD11/CD18 mAb prevents vasospasm after SAH by inhibiting adhesion of neutrophils and macrophages and their migration into the periadventitial space.

Role of ferrous iron chelator 2,2′-dipyridyl in preventing delayed vasospasm in a primate model of subarachnoid hemorrhage

1998 ◽  
Vol 88 (2) ◽  
pp. 298-303 ◽  
Author(s):  
Laura L. Horky ◽  
Ryszard M. Pluta ◽  
Robert J. Boock ◽  
Edward H. Oldfield
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Blood Clot ◽  
Autologous Blood ◽  
Iron Chelator ◽  
Preventive Therapy ◽  
Control Group ◽  
Primate Model ◽  
Content Type ◽  
Fine Print

Object. Oxyhemoglobin (HbO2) causes vasospasm after subarachnoid hemorrhage (SAH). The most likely spasmogenic component of HbO2 is iron. Various iron chelators, such as deferoxamine, have prevented vasospasm in vivo with limited success. However, only chelators of iron in the ferric state have been studied in animal models of vasospasm after SAH. Because free radical formation requires the ferrous (Fe++) moiety and Fe++ is a potent binder of the vasodilator nitric oxide, the authors hypothesized that iron in the ferrous state causes vasospasm and that chelators of Fe++, such as 2,2′-dipyridyl, may prevent vasospasm. This study was undertaken to investigate the influence of 2,2′-dipyridyl on vasospasm after induction of SAH in a primate model. Methods. Twelve cynomolgus monkeys were randomly divided into two groups and then both groups underwent placement of an arterial autologous blood clot in the subarachnoid space around the right middle cerebral artery (MCA). The five animals in the control group received intravenously administered saline and the seven treated animals received intravenously administered chelator (2,2′-dipyridyl) for 14 days. Sequential arteriography for assessment of MCA diameter was performed before and on the 7th day after SAH. Conclusions. Prevention of cerebral vasospasm by means of treatment with continuous intravenous administration of 2,2′-dipyridyl is reported in a primate model of SAH. This result provides insight into the possible mechanism of delayed vasospasm after aneurysmal SAH and provides a potential preventive therapy for it.

The effect of subarachnoid hemorrhage on mechanisms of vasodilation mediated by cyclic adenosine monophosphate

1998 ◽  
Vol 89 (1) ◽  
pp. 111-117 ◽  
Author(s):  
Hisashi Onoue ◽  
Zvonimir S. Katusic
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Adenylate Cyclase ◽  
Autologous Blood ◽  
Delayed Rectifier ◽  
Relaxation Response ◽  
Content Type ◽  
Cyclase Activation ◽  
Adenylate Cyclase Activation ◽  
Basilar Arteries ◽  
Fine Print

Object. This study was designed to determine whether subarachnoid hemorrhage (SAH) affects the function of the K+ channels responsible for relaxation of canine cerebral arteries in response to adenylate cyclase activation. Methods. The effect of K+ channel inhibitors on the arterial relaxation response to forskolin, a direct adenylate cyclase activator, was studied in rings of basilar arteries obtained from normal dogs and dogs in which SAH was induced (double-hemorrhage model). The levels of adenosine 3′,5′-cyclic monophosphate (cAMP) were measured using the radioimmunoassay technique. In rings with the endothelium removed, relaxation induced by forskolin was not affected by SAH. The relaxation response to forskolin was reduced by charybdotoxin (1027 mol/L), a selective Ca++-activated K+ channel inhibitor, in normal arteries and arteries subjected to autologous blood injection. This inhibitory effect of charybdotoxin was significantly greater in arteries involved in SAH than in normal vessels. The relaxation response to forskolin was reduced by 4-aminopyridine (10−3 mol/L), a delayed rectifier K+ channel inhibitor, only in arteries involved in SAH. In contrast, the relaxation response to forskolin was not affected by glyburide (10−5 mol/L), an adenosine 5′—triphosphate-sensitive K+ channel inhibitor, in both normal and SAH arteries. Forskolin (3 × 10−7 mol/L) produced an approximately 10-fold increase in levels of cAMP. The basal values and increased levels of cAMP detected after stimulation with forskolin were no different in normal arteries and those exposed to SAH. Conclusions. These results demonstrate that formation of cAMP and the relaxation response to adenylate cyclase activation are not affected by SAH. However, in diseased arteries, K+ channels assume a more important role in the mediation of relaxation response to forskolin, indicating that SAH may change the mechanisms responsible for vasodilation induced by cAMP.

Suramin-induced reversal of chronic cerebral vasospasm in experimental subarachnoid hemorrhage

2002 ◽  
Vol 97 (1) ◽  
pp. 129-135 ◽  
Author(s):  
Hitoshi Kimura ◽  
Toshinari Meguro ◽  
Ahmed Badr ◽  
John H. Zhang
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Tyrosine Kinase ◽  
Cerebral Vasospasm ◽  
Disulfonic Acid ◽  
Control Group ◽  
Content Type ◽  
Basilar Arteries ◽  
Blood Injection ◽  
The Mean ◽  
Fine Print

Object. The naphthylsulfonate derivative suramin is an inhibitor of growth factor receptors (receptor tyrosine kinases) and G protein—coupled P2Y receptors. Both types of these receptors are suspected of being involved in cerebral vasospasm after subarachnoid hemorrhage (SAH). In the current study, the authors examined the therapeutic effects of suramin and a selective P2X-receptor antagonist, pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS), in the reversal of vasospasm in an established canine double-hemorrhage model. Methods. Twenty-four dogs underwent double blood injection into the cisterna magna, with injections given on Days 0 and 2. The dogs were divided randomly into three groups (six animals in each group) to be treated from Days 2 through 6 with the vehicle dimethyl sulfoxide, suramin, or PPADS. An additional group of six dogs received double blood injection without any treatment and served as an SAH control group. The animals were killed on Day 7. Angiography was performed on Day 0 before blood injection and again on Day 7 before the animals were killed. After the death of the animals, the basilar arteries (BAs) were collected for morphological studies and determination of tyrosine kinase expression, and the bloody cerebrospinal fluid (CSF) produced by the hemorrhages was collected for measurement of oxyhemoglobin and adenosine triphosphate (ATP). In the SAH control group, the mean diameter of the BAs on Day 7 was 46.23 ± 6.32% of the value on Day 0 (which served as a reference of 100%). In the DMSO-treated group, the mean residual diameter of the BA was 47.77 ± 0.8% on Day 7 compared with the value on Day 0. Suramin, but not PPADS, increased the residual diameter to 74.02 ± 4.24% on Day 7. On Day 7 the level of ATP in the CSF was decreased and the level of oxyhemoglobin was increased, compared with values measured on Day 0. Suramin, but not PPADS, reduced tyrosine phosphorylation in the spastic BAs. Conclusions. By reducing tyrosine kinase activity, suramin may be useful in the treatment of cerebral vasospasm.

Evaluation of the microvasculature and cerebral ischemia after experimental subarachnoid hemorrhage in dogs

2002 ◽  
Vol 97 (4) ◽  
pp. 896-904 ◽  
Author(s):  
Eddie Perkins ◽  
Hitoshi Kimura ◽  
Andrew D. Parent ◽  
John H. Zhang
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Morphological Characteristics ◽  
Ultrastructural Level ◽  
Ultrastructural Changes ◽  
Control Group ◽  
Internal Elastic Lamina ◽  
Content Type ◽  
Basilar Arteries ◽  
Experimental Subarachnoid Hemorrhage ◽  
Fine Print

Object. Whether cerebral vasospasm occurs only in surface vessels or also in parenchymal arterioles is debatable. The present study was undertaken to evaluate comprehensively the microvasculature of the brainstem after experimental subarachnoid hemorrhage (SAH). Methods. Nine mongrel dogs of either sex, each weighing between 18 and 24 kg, underwent double blood injections spaced 48 hours apart; the injections were infused into the cisterna magna immediately after angiography of the basilar arteries (BAs). Three additional dogs assigned to a control group received no blood injections. The dogs were killed on Day 7. Axial sections obtained from the midpontine region of both control dogs and animals subjected to SAH were evaluated with respect to the morphological characteristics of vessels and neurons, and for ultrastructural changes. Severe vasospasm occurred in the BAs of all dogs subjected to SAH. Nevertheless, in these animals, the luminal areas and vessel perimeter in parenchymal arterioles, but not in parenchymal venules, were observed to have increased when compared with those of control dogs (p < 0.01, t-test). No corrugation of the internal elastic lamina was observed and smooth-muscle and endothelial cells remained normal at the ultrastructural level in the dogs with SAH. Conclusions. In this model, vasospasm of the BAs did not extend into the region of the pons to affect the intraparenchymal arterioles. Dilation of the parenchymal arterioles might serve as compensation for reduced blood flow. Thus, no neuronal ischemia or infarction resulted in the pontine region of the brain.

Antisense preproendothelin-oligoDNA therapy for vasospasm in a canine model of subarachnoid hemorrhage

1999 ◽  
Vol 90 (6) ◽  
pp. 1105-1114 ◽  
Author(s):  
Hiroki Ohkuma ◽  
Ian Parney ◽  
Joseph Megyesi ◽  
Aziz Ghahary ◽  
J. Max Findlay
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Dna Sequences ◽  
Combined Treatment ◽  
Canine Model ◽  
Clot Lysis ◽  
Therapeutic Effects ◽  
Causative Role ◽  
Content Type ◽  
Basilar Arteries ◽  
Fine Print

Object. The purpose of this study is twofold: 1) to test antisense genetic techniques used in the prevention of cerebral vasospasm in a canine model of subarachnoid hemorrhage (SAH), targeting the endothelin-1 (ET-1) gene; and 2) to determine if fibrinolysis of subarachnoid clot with recombinant tissue plasminogen activator (rtPA) could enhance the effect of antisense treatment.Methods. A total of 39 dogs were studied in this experiment. Placebo (six animals), rtPA (six animals), antisense preproET-1 oligodeoxynucleotide (ASOD; five animals), or rtPA plus ASOD (combined treatment; six animals) was injected into the cisterna magna 30 minutes after a second SAH was induced on the 2nd day of the experiment. The animals were observed until Day 7, when they underwent follow-up angiography and then were killed; their basilar arteries were removed for analysis. Control animals included in this study (two animals in each group) received placebo, rtPA, ASOD, or rtPA plus ASOD without induction of SAH, or rtPA with mismatched (nonsense) preproET-1 oligodeoxynucleotide following SAH. Six additional dogs were analyzed earlier following SAH.Dogs that received placebo developed severe vasospasm (51 ± 8% of baseline caliber). Administration of ASOD alone resulted in a mild reduction in vasospasm (64 ± 13% of baseline caliber) and rtPA alone resulted in a moderate reduction in vasospasm (81 ± 5% of baseline caliber); however, the combined therapy of rtPA plus ASOD almost completely prevented vasospasm (95 ± 6% of baseline caliber), which was significantly different from all other groups (p < 0.05). Morphological analysis of the basilar arteries yielded results similar to angiography with respect to vasospasm severity. The ASOD treatment combined with rtPA resulted in reduced ET-1 expression, as demonstrated by immunohistochemical staining of the arteries, and reduced preproET-1 levels on Day 4, as measured by reverse transcription—polymerase chain reaction. Nonsense DNA sequences had no effect on the vessels.Conclusions. Antisense preproET-1 oligodeoxynucleotide treatment, when combined with clot lysis caused by rtPA, reduced vasospasm in the canine model of SAH, and this effect appeared to be related to reduced ET-1 synthesis. The results of this experiment support a causative role for ET-1 early in the course of vasospasm development in dogs. The apparent additive therapeutic effects of antisense and fibrinolytic treatments could be due to clot lysis, which allows better delivery of oligodeoxynucleotides to arteries within the subarachnoid space.

Effects of the Ca++-permeable nonselective cation channel blocker LOE 908 on subarachnoid hemorrhage—induced vasospasm in the basilar artery in rabbits

2003 ◽  
Vol 98 (3) ◽  
pp. 561-564 ◽  
Author(s):  
Yoshifumi Kawanabe ◽  
Tomoh Masaki ◽  
Nobuo Hashimoto
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Intravenous Administration ◽  
Basilar Artery ◽  
Channel Blocker ◽  
Autologous Blood ◽  
Content Type ◽  
Dependent Part ◽  
Before And After ◽  
Fine Print

Object. The Ca++ influx into vascular smooth-muscle cells (VSMCs) plays a fundamental role in the development and chronic effects of vasospasm after subarachnoid hemorrhage (SAH). The Ca++-permeable nonselective cation channels (NSCCs) are activated by several endothelium-derived constricting factors such as endothelin 1 (ET-1) and thromboxane A2. Moreover, the receptor-operated Ca++ channel blocker LOE 908 inhibits ET-1—induced extracellular Ca++ influx via NSCCs in the VSMCs of the basilar artery (BA) and the NSCC-dependent part of ET-1—induced vasoconstriction of BA rings. The purpose of the present study was to evaluate the in vivo role of LOE 908 on SAH-induced vasospasm. Methods. Forty-two Japanese white rabbits were assigned to seven groups. Treatment groups consisted of the following: 1) control rabbits without SAH that received a cisternal injection of saline; 2) rabbits with SAH that were subjected to the intravenous administration of saline; 3 through 6) rabbits with SAH that underwent the intravenous administration of 0.01, 0.1, 1, or 10 mg/kg LOE 908, respectively; and 7) rabbits without SAH that underwent the intravenous administration of 10 mg/kg LOE 908. Autologous blood was injected into the cisterna magna. The caliber of the BA was measured on angiographic studies before and after the cisternal injection of autologous blood. The intravenous injection of LOE 908 inhibited the magnitude of an SAH-induced vasosapsm. In addition, the concentration of LOE 908 required to relax vasospasm (1 mg/kg) correlated with that required to block Ca++ influx into VSMCs. Conclusions. The Ca++ channel blocker LOE 908 may inhibit the magnitude of an SAH-induced vasospasm by blocking the influx of Ca++ through NSCCs in rabbit BAs. Blocking the NSCCs may represent a new treatment for cerebral vasospasm after SAH.

Effect of the 21-aminosteroid U-74006F on cerebral vasospasm following subarachnoid hemorrhage

1989 ◽  
Vol 71 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Mario Zuccarello ◽  
Jeffery T. Marsch ◽  
Gerald Schmitt ◽  
James Woodward ◽  
Douglas K. Anderson
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Basilar Artery ◽  
Autologous Blood ◽  
Contrast Material ◽  
Rabbit Model ◽  
Membrane Lipid ◽  
Basilar Arteries ◽  
Flow Through ◽  
Chronic Vasospasm

✓ The purpose of this study was to use a new 21-aminosteroid (U-74006F) with in vitro antioxidant and antilipolytic properties as a pharmacological probe to assess the role of lipid hydrolysis and peroxidation in a rabbit model of subarachnoid hemorrhage (SAH)-induced vasospasm. Cerebral angiograms were performed on 15 rabbits. Eighteen hours later, 1 cc/kg of autologous blood was infused into the cisterna magna of all 15 animals. Six rabbits received no treatment, six received U-74006F starting 30 minutes after SAH, and three rabbits received the vehicle for U-74006F starting 30 minutes after SAH. At 72 hours post-SAH, a second angiogram was obtained. Digital subtraction angiographic techniques were used to measure the diameter of and contrast material flow through the basilar artery. At 72 hours post-SAH, vasospasm was evident in all untreated and vehicle-treated rabbits. The diameter of and the flow through the basilar artery were significantly reduced 42.3% ± 6.6% and 46.8% ± 5.8%, respectively, below pre-SAH levels (means ± standard error of the means). Treatment with U-74006F eliminated the SAH-induced vasospasm; in treated animals, both the flow through and the diameter of the basilar arteries were at pre-SAH levels. These findings indicate that: 1) membrane lipid changes (that is, hydrolysis with eicosanoid production and/or peroxidation) contribute to the chronic vasospasm resulting from SAH, and 2) U-74006F prevents the SAH-induced chronic vasospasm in this model by limiting these pathological membrane events.

Contribution of Src tyrosine kinase to cerebral vasospasm after subarachnoid hemorrhage

2003 ◽  
Vol 99 (2) ◽  
pp. 383-390 ◽  
Author(s):  
Gen Kusaka ◽  
Hitoshi Kimura ◽  
Ikuyo Kusaka ◽  
Eddie Perkins ◽  
Anil Nanda ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Tyrosine Kinase ◽  
Cerebral Vasospasm ◽  
Mitogen Activated Protein Kinase ◽  
Src Tyrosine Kinase ◽  
Content Type ◽  
Upstream Regulator ◽  
Src Inhibitor ◽  
Basilar Arteries ◽  
Fine Print

Object. Mitogen-activated protein kinase (MAPK) has been implicated in cerebral vasospasm after subarachnoid hemorrhage (SAH). This study was conducted to investigate whether Src tyrosine kinase, an upstream regulator of MAPK, is involved in cerebral vasospasm. Methods. An established canine double-hemorrhage model was used. Twenty-four dogs were divided into four groups: control, vehicle-treated, Src inhibitor PP2—treated, and Src inhibitor damnacanthal—treated groups. Vehicle (dimethyl sulfoxide), PP2, or damnacanthal was injected daily into the cisterna magna of 18 dogs at 3 to 6 days after induction of SAH. Angiography was performed on Day 0 (the day on which the first blood injection was administered to induce SAH) and on Day 7. Western blot analysis of Src and MAPK activation in basilar arteries (BAs) collected on Day 7 post-SAH was performed. Severe vasospasm was observed in the BAs of vehicle-treated dogs. Mild vasospasm was observed in all dogs treated with Src inhibitors. Phosphorylated Src and MAPK were increased after SAH and activation of these kinases in the BAs was abolished by PP2 and damnacanthal. Conclusions. The tyrosine kinase Src is an important upstream regulator of MAPK, and inhibition of Src might offer a new therapy in the management of cerebral vasospasm.

Source and cause of endothelin-1 release into cerebrospinal fluid after subarachnoid hemorrhage

1997 ◽  
Vol 87 (2) ◽  
pp. 287-293 ◽  
Author(s):  
Ryszard M. Pluta ◽  
Robert J. Boock ◽  
John K. Afshar ◽  
Kathleen Clouse ◽  
Mima Bacic ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cerebrospinal Fluid ◽  
Subarachnoid Hemorrhage ◽  
Cerebral Ischemia ◽  
Cerebral Vasospasm ◽  
Plasma Levels ◽  
Transient Cerebral Ischemia ◽  
Content Type ◽  
Endothelin 1 ◽  
Fine Print

✓ Despite years of research, delayed cerebral vasospasm remains a serious complication of subarachnoid hemorrhage (SAH). Recently, it has been proposed that endothelin-1 (ET-1) mediates vasospasm. The authors examined this hypothesis in a series of experiments. In a primate model of SAH, serial ET-1 levels were measured in samples from the perivascular space by using a microdialysis technique and in cerebrospinal fluid (CSF) and plasma during the development and resolution of delayed vasospasm. To determine whether elevated ET-1 production was a direct cause of vasospasm or acted secondary to ischemia, the authors also measured ET-1 levels in plasma and CSF after transient cerebral ischemia. To elucidate the source of ET-1, they measured its production in cultures of endothelial cells and astrocytes exposed to oxyhemoglobin (10 µM), methemoglobin (10 µM), or hypoxia (11% oxygen). There was no correlation between the perivascular levels of ET-1 and the development of vasospasm or its resolution. Cerebrospinal fluid and plasma levels of ET-1 were not affected by vasospasm (CSF ET-1 levels were 9.3 ± 2.2 pg/ml and ET-1 plasma levels were 1.2 ± 0.6 pg/ml) before SAH and remained unchanged when vasospasm developed (7.1 ± 1.7 pg/ml in CSF and 2.7 ± 1.5 pg/ml in plasma). Transient cerebral ischemia evoked an increase of ET-1 levels in CSF (1 ± 0.4 pg/ml at the occlusion vs. 3.1 ± 0.6 pg/ml 4 hours after reperfusion; p < 0.05), which returned to normal (0.7 ± 0.3 pg/ml) after 24 hours. Endothelial cells and astrocytes in culture showed inhibition of ET-1 production 6 hours after exposure to hemoglobins. Hypoxia inhibited ET-1 release by endothelial cells at 24 hours (6.4 ± 0.8 pg/ml vs. 0.1 ± 0.1 pg/ml, control vs. hypoxic endothelial cells; p < 0.05) and at 48 hours (6.4 ± 0.6 pg/ml vs. 0 ± 0.1 pg/ml, control vs. hypoxic endothelial cells; p < 0.05), but in astrocytes hypoxia induced an increase of ET-1 at 6 hours (1.5 ± 0.6 vs. 6.4 ± 1.1 pg/ml, control vs. hypoxic astrocytes; p < 0.05). Endothelin-1 is released from astrocytes, but not endothelial cells, during hypoxia and is released from the brain after transient ischemia. There is no relationship between ET-1 and vasospasm in vivo or between ET-1 and oxyhemoglobin, a putative agent of vasospasm, in vitro. The increase in ET-1 levels in CSF after SAH from a ruptured intracranial aneurysm appears to be the result of cerebral ischemia rather than reflecting the cause of cerebral vasospasm.

Alterations of mechanical properties in canine basilar arteries after subarachnoid hemorrhage

1989 ◽  
Vol 71 (3) ◽  
pp. 430-436 ◽  
Author(s):  
Phyo Kim ◽  
Thoralf M. Sundt ◽  
Paul M. Vanhoutte
Keyword(s):  
Mechanical Properties ◽  
Subarachnoid Hemorrhage ◽  
Autologous Blood ◽  
Myogenic Tone ◽  
Control Group ◽  
Resting Tension ◽  
Length Contraction ◽  
Basilar Arteries ◽  
Chronic Vasospasm

✓ The purpose of this study was to examine the hypotheses that structural stiffening of the arterial wall contributes to chronic cerebral vasospasm, and that alteration in properties of smooth muscle takes place after subarachnoid hemorrhage (SAH). Subarachnoid hemorrhage and subsequent chronic vasospasm were induced in dogs by two cisternal injections of autologous blood (on Day 0 and Day 2). Vasospasm was confirmed by angiography performed on Day 0 and Day 7. Animals in the control group underwent angiography only. On Day 8, the mechanical properties of the basilar arteries were studied in vitro. Passive compliance, measured under total inhibition of spontaneous myogenic tone with diltiazem (10−4 M) plus papaverine (10−4 M) was smaller in the SAH group. The length-contraction curve was shifted to the left and the optimum length for maximum contraction (Lmax) was significantly shorter in the spastic blood vessels. The spontaneous myogenic tone was augmented in the SAH group, resulting in an increase in resting tension at each length. By contrast, the maximum contractions in response to KCl and uridine 5′-triphosphate were markedly reduced in the SAH group, without changes in sensitivity to these agents. These differences in mechanical properties were observed in rings both with and without endothelium. The results indicate that, in chronic vasospasm, stiffening of the noncontractile component of the vasculature takes place as well as alterations in the contractile component, both of which presumably contribute to the shift in resting length-tension relationship and length-contraction relationship of the artery. The decreased distensibility, the increase in resting tension, and the shortening of the Lmax all favor a smaller diameter of the artery after SAH, possibly contributing to vasospasm.

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