Rat Common Carotid Artery Research Articles

Catheterization of the Hepatic Artery Via the Left Common Carotid Artery in Rats

The commonly used approach for rat hepatic artery catheterization is via the gastroduodenal artery, which is ligated after the procedure. A new method of rat hepatic artery catheterization via the left common carotid artery (LCCA) is described. The LCCA is repaired after catheterization. The catheterization procedures included the following: (1) opening the rat's abdominal cavity and exposing the portion of abdominal aorta at the level of the celiac trunk; (2) separating and exposing the LCCA; inserting a microguidewire and microcatheter set into the LCCA via an incision; after placement into the descending aorta, the microguidewire and microcatheter are maneuvered into the hepatic artery under direct vision; (3) after transcatheter therapy, the catheter is withdrawn and the incision at the LCCA is repaired. This technique was employed on 60 male Sprague-Dawley rats with diethylnitrosamine-induced liver cancer, using a 3F microguidewire and microcatheter set. Selective hepatic artery catheterization was successfully performed in 57 rats. One rat died during the operation and five rats died within 7 days after the procedure. It is envisaged that as experience increases, the catheterization success rate will increase and the death rate will decrease. A new approach for selective hepatic artery catheterization via the LCCA in rats is introduced, which makes repeat catheterization of this artery possible and allows large embolization particles to be delivered by using a 3F catheter.

Zaltoprofen, a non-steroidal anti-inflammatory drug, inhibits bradykinin-induced pain responses without blocking bradykinin receptors

Zaltoprofen, a preferential COX-2 inhibitor, exhibited a potent inhibitory action on the nociceptive responses induced by a retrograde infusion of bradykinin into the right common carotid artery in rats. However, other COX-2 preferential inhibitors such as meloxicam and etodolac did not exhibit any apparent action, and also, preferential COX-1 inhibitors mofezolac and indomethacin, COX-1 and COX-2 inhibitor loxoprofen sodium showed a weak effect. These non-steroidal anti-inflammatory drugs (NSAIDs) except for zaltoprofen, strongly inhibited an acetic acid-induced writhing response related to PGs based on COX-1, at lower doses. Zaltoprofen had a moderate inhibitory effect compared with those of the above-mentioned NSAIDs. These results suggest that the inhibitory effect of zaltoprofen on bradykinin-induced nociceptive responses is not explainable by the inhibition of cyclooxygenase (COX). So, we examined the inhibitory effect of zaltoprofen on bradykinin-induced nociceptive responses by performing several in vitro experiments. Zaltoprofen did not bind to B 1 and B 2 receptors in a radio-ligand binding assay. In the cultured dorsal root ganglion cells of mature mice, zaltoprofen completely inhibited the bradykinin-induced increase of [Ca 2+] i, which was inhibited by B 2 antagonist D-Arg-[Hyp 3, Thi 5,8, D-Phe 7]-bradykinin, but not by B 1 antagonist. In addition, the inhibition of zaltoprofen on the increase of [Ca 2+] i was observed even under extracellular Ca 2+-free conditions. The above results suggest that zaltoprofen produces an analgesic action on bradykinin-induced nociceptive responses by blocking the B 2 receptor-mediated pathway in the primary sensory neurons. Taken together, these results suggest that zaltoprofen may serve as a potent and superior analgesic for the treatment of pain.

The 5-Hydroxytryptamine2A Receptor Antagonist Sarpogrelate Hydrochloride Inhibits Acute Platelet Aggregation in Injured Endothelium

In this study, the effect of sarpogrelate hydrochloride, a 5-hydroxytryptamine2A receptor antagonist, on platelet aggregation at the site of injured carotid artery endothelium was examined. The rat common carotid artery was clamped for 30 min to induce endothelial injury. Sarpogrelate hydrochloride was administered before and after the injury, and the effects were compared with those in rats receiving sham operation only and those receiving clipping injury but no sarpogrelate hydrochloride. The animals were killed 24 h after the procedure. The common carotid artery was examined by scanning electron microscopy and stained immunochemically for factor VIII. Sarpogrelate hydrochloride treatment was associated with reduced aggregation of platelets on electron microscopy and lower expression of factor VIII at the injured intima. Sarpogrelate hydrochloride has an inhibitory effect on platelet aggregation at the intima in the acute stage after injury, suggesting that this drug may be used to prevent early ischaemic complications after surgical or endovascular arterial intervention.

Enhanced brain angiogenesis in chronic cerebral hypoperfusion after administration of plasmid human vascular endothelial growth factor in combination with indirect vasoreconstructive surgery

Vascular endothelial growth factor (VEGF) is a secreted mitogen associated with angiogenesis. The conceptual basis for therapeutic angiogenesis after plasmid human VEGF gene (phVEGF) transfer has been established in patients presenting with limb ischemia and myocardial infarction. The authors hypothesized that overexpression of VEGF using a gene transfer method combined with indirect vasoreconstruction might induce effective brain angiogenesis in chronic cerebral hypoperfusion, leading to prevention of ischemic attacks. A chronic cerebral hypoperfusion model induced by permanent ligation of both common carotid arteries in rats was used in this investigation. Seven days after induction of cerebral hypoperfusion, encephalomyosynangiosis (EMS) and phVEGF administration in the temporal muscle were performed. Fourteen days after treatment, the VEGF gene therapy group displayed numbers and areas of capillary vessels in temporal muscles that were 2.2 and 2.5 times greater, respectively, in comparison with the control group. In the brain, the number and area of capillary vessels in the group treated with the VEGF gene were 1.5 and 1.8 times greater, respectively, relative to the control group. In rat models of chronic cerebral hypoperfusion, administration of phVEGF combined with indirect vasoreconstructive surgery significantly increased capillary density in the brain. The authors' results indicate that administration of phVEGF may be an effective therapy in patients with chronic cerebral hypoperfusion, such as those with moyamoya disease.

Oxidized LDL receptor LOX-1 is involved in neointimal hyperplasia after balloon arterial injury in a rat model

LOX-1 is a multi-ligand receptor originally identified as the endothelial oxidized LDL receptor. LOX-1 expression is also induced in smooth muscle cells in response to proinflammatory and oxidative stimuli. Here, we report on the role of LOX-1 in intimal hyperplasia, in which proinflammatory and oxidative stimuli are increased. Left common carotid artery of rat was injured by a balloon catheter. The expression of LOX-1 was significantly increased within 24 h after the balloon injury and peaked at day 7. LOX-1 expression was observed predominantly in medial smooth muscle cells until day 3, and then shifted to predominantly intimal smooth muscle cells. At day 14, the expression was concentrated in the regenerated endothelial cells. To examine the contributory role of LOX-1 in the growth of intimal smooth muscle cells, rats were administered anti-LOX1 antibody intravenously every 3 days after balloon injury. Anti-LOX-1 antibody administration effectively suppressed intimal hyperplasia, oxidative stress, and leukocyte infiltration compared with control IgG. These findings suggest the importance of LOX-1 expression in the pathogenesis of neointimal formation in conjunction with oxidative stress and leukocyte infiltration. The LOX-1 expressed in smooth muscle cells is involved in intimal hyperplasia in a rat model of balloon injury. Manipulation of LOX-1 activity is a novel potential therapeutic target to prevent restenosis after angioplasty.

Microsphere embolism‐induced cortical cholinergic deafferentation and impairments in attentional performance

Ischemic events have been hypothesized to play a critical role on the pathogenesis of dementia and the acceleration of cognitive impairments. This experiment was designed to determine the consequences of microvascular ischemia on the cortical cholinergic input system and associated attention capacities. Injections of microspheres ( approximately 50 microm diameter; approximately 5000 microspheres/100 microL) into the right common carotid artery of rats served as a model of microvascular ischemia and resulted in decreases in the density of cholinergic fibers in the ipsilateral medial prefrontal cortex and frontoparietal areas. Furthermore, dense astrogliosis, indicated by glial fibrillary acidic protein (GFAP) immunohistochemistry, was observed in the globus pallidus, including the areas of origin of cholinergic projections to the cortex. Fluoro-Jade B staining indicated that loss of neurons in the cortex was restricted to areas of microsphere-induced infarcts. Attentional performance was assessed using an operant sustained attention task; performance in this task was previously demonstrated to reflect the integrity and activity of the cortical cholinergic input system. Embolized animals' performance was characterized by a decrease in the animals' ability to detect signals. Their performance in non-signal trials remained unaffected. The residual density of cholinergic axons in prefrontal and frontoparietal areas correlated with the animals' performance. The present data support the hypothesis that microvascular ischemia results in loss of cortical cholinergic inputs and impairs associated attentional performance. Microsphere embolism represents a useful animal model for studying the role of interactions between microvascular disorder and impaired forebrain cholinergic neurotransmission in the manifestation of cognitive impairments.

Closing microvascular lesions with fibrin sealant-attached muscle pads

Fibrin sealants are used in a variety of surgical procedures, mainly for purposes of hemostasis and assisted wound healing. The combined use of fibrin sealant and autologous muscle pads for hemostasis was not reported previously. Arterial incisions in the common carotid artery in rats were closed by the combined application of fibrin sealant and an autologous muscle pad. Postsurgical vessel patency and degree of stenosis were evaluated by color duplex sonography, computed tomography angiography, and postmortem histology. The combined application of muscle pad and fibrin sealant and achievement of hemostasis was feasible in all animals. Seventy-eight percent of animals showed no or only slight postsurgical vessel stenosis. Our method is simple and quick to perform, showing a high potential for hemostasis in microvascular lesions. Therefore, it might be used in future experimental studies for conservation of vessel patency after arterial catheterization and in experimental or clinical vascular surgery.

Perivascular delivery of neomycin inhibits the activation of NF-κB and MAPK pathways, and prevents neointimal hyperplasia and stenosis after arterial injury

The nuclear transcription factor kappaB (NF-κB) is a cytoplasmic dimer that, as the family of mitogen-activated protein kinase (MAPK), can directly regulate the expression of early genes and genes involved in the stress response, following a variety of physiological or pathological stimuli. Both of them stimulate the transcription of many proteins, which are considered important during inflammation. A crucial role has been assigned to these factors in cellular proliferation and in neointimal hyperplasia secondary to the endothelial lesion of arterial vessels. On the other hand, it has been described that neomycin can have an inhibitory function on tumor cell proliferation, through the inhibition of different intracellular pathways of signaling, among them the NF-κB and MAPK pathways. Rat common carotid artery was subjected to balloon angioplasty. Neomycin sulfate (18 mg) was applied using pluronic acid gel on the adventitial surface of the injured vessel. MAPK and NF-κB activation was quantified after 24 hours with immunohistochemical staining. Neointimal formation was quantified after 14 days with morphometry. Immunohistochemistry results demonstrating MAPK and NF-κB activation reveal that both transcription factors are activated in the media of the control vessel wall. In contrast, the immunoreactivity for MAPK and NF-κB in the sections obtained from arteries treated with neomycin over 24 hours was insufficient or nonexistent. Treatment with neomycin on adventitia over 14 days in arteries on which angioplasty was performed shows a neointimal index (intimal area/medial area) decrease of 71% in comparison with arteries that were not treated. The adventitial neomycin treatment over 14 days produces a very significant increase (287.5%; p<0.0001) in the arterial luminal circumference in comparison with arteries treated with vehicle. These results support the theory that neomycin plays an important role against neointimal hyperplasia through the inhibition of MAPK and NF-κB activation.

Diazoxide and dimethyl sulphoxide alleviate experimental cerebral hypoperfusion-induced white matter injury in the rat brain

Aging and dementia are accompanied by cerebral white matter (WM) injury, which is considered to be of ischemic origin. A causal link between cerebral ischemia and WM damage has been demonstrated in rats; however, few attempts appear to have been made to test potential drugs for the alleviation of ischemia-related WM injury. We induced cerebral hypoperfusion via permanent, bilateral occlusion of the common carotid arteries of rats. A mitochondrial ATP-sensitive potassium channel opener diazoxide (5 mg/kg) or its solvent dimethyl sulphoxide (DMSO) was administered i.p. (0.25 ml) on 5 consecutive days after surgery. Sham-operated animals served as control for surgery, and non-treated rats as controls for treatments. Thirteen weeks after surgery, the animals were sacrificed and astrocytes and microglia were labeled immunocytochemically in the internal capsule, the corpus callosum and the optic tract. The astrocytic proliferation was enhanced by cerebral hypoperfusion in the optic tract, and reduced by diazoxide in DMSO, but not by DMSO alone in the corpus callosum. After carotid artery occlusion, microglial activation was enhanced two-fold in the corpus callosum and four-fold in the optic tract. DMSO decreased microglial activation in the optic tract, while diazoxide in DMSO, but not DMSO alone, restored microglial activation to the control level in the corpus callosum. In summary, the rat optic tract appeared to be particularly vulnerable to ischemia, while the effect of diazoxide was restricted to the corpus callosum. We conclude that diazoxide dissolved in DMSO can moderate ischemia-related neuroinflammation by suppressing glial reaction in selective cerebral WM areas.

Perivascular gene transfer of NADPH oxidase inhibitor suppresses angioplasty-induced neointimal proliferation of rat carotid artery.

Vascular stretch induces NADPH oxidase-derived superoxide anion (O2-), which has been implicated in hypertrophy and cell proliferation. We hypothesized that targeted delivery of an NADPH oxidase inhibitor to the adventitia would reduce stretch-induced vascular O2- and attenuate neointima formation. We designed a novel replication-deficient adenovirus containing a fibroblast-active promoter driving expression of NADPH oxidase inhibitory sequence gp91ds (Ad-PDGFbetaR-gp91ds/eGFP). 1) We characterized the specificity of this promoter using pPDGFbetaR-luciferase by showing induction of luciferase in cultured rat aortic fibroblasts but not in vascular smooth muscle cells. 2) Using RT-PCR, we observed expression of gp91ds and the reporter gene in fibroblasts after infection with Ad-PDGFbetaR-gp91ds/eGFP. 3) Using Ad-CMV-eGFP as a control, we delivered Ad-PDGFbetaR-gp91ds/eGFP to the adventitia of the rat common carotid artery (CCA). Immunohistochemistry confirmed localized delivery of the inhibitor to the adventitia. After CCAs were injured with an embolectomy catheter, we observed a significant increase in neointima-to-media area ratio in control CCAs, which was significantly attenuated in CCAs treated with the gp91ds-expressing virus. In a second group of rats, we detected a 10-fold increase in distension-stimulated O2-, which was significantly reduced in CCAs infected with gp91ds-expressing virus. These data demonstrate that localized adventitial delivery of an NADPH oxidase inhibitor is effective in reducing overall vascular O2- and neointima formation, suggesting that adventitial NADPH oxidase plays a functional role in development of neointimal hyperplasia.

The protective effect of superoxide dismutase mimetic M40401 on balloon injury-related neointima formation: role of the lectin-like oxidized low-density lipoprotein receptor-1.

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), the principal receptor for oxidized low-density lipoprotein (ox-LDL) in vascular endothelial cells (ECs), has recently been suggested to exert a pivotal role in atherogenesis, possibly by mediating ox-LDL-evoked endothelial dysfunction. On the other hand, LOX-1 expression seems to strongly correlate with the oxidative stress occurring in the vascular wall of experimentally injured blood vessels. Here, we investigated LOX-1 expression and superoxide generation during neointima formation in a balloon injury rat carotid artery model. To test this, we used M40401 [a manganese(II) complex with a bis(cyclo-hexylpyridine-substituted) macrocyclic ligand], a synthetic superoxide dismutase mimetic that is a selective scavenger of superoxide. The injury was performed inserting the balloon catheter through the rat common carotid artery and after 14 days a histopathological analysis revealed a significant restenosis with smooth muscle cell proliferation and neointima formation that was associated with an enhanced expression of LOX-1, nitrotyrosine (the footprint of peroxynitrite) staining, and lipid peroxidation as assessed by malondialdehyde (MDA) formation. Pretreatment of rats with M40401 (0.5-10 mg/kg i.p. daily) reduced neointima formation, MDA accumulation, nitrotyrosine staining, and LOX-1 expression. Here, we show that removal of superoxide formation occurring in injured arteries reduces both neointima formation and LOX-1 expression and that this may represent a novel therapeutical approach in the treatment of vascular disorders in which proliferation of vascular smooth muscle cells and ox-LDL-related endothelial cell dysfunction occur.

Diazoxide and dimethyl sulphoxide prevent cerebral hypoperfusion-related learning dysfunction and brain damage after carotid artery occlusion

Chronic cerebral hypoperfusion, a mild ischemic condition is associated with advancing age and severity of dementia; however, no unanimous therapy has been established to alleviate related neurological symptoms. We imposed a permanent, bilateral occlusion of the common carotid arteries of rats ( n=18) to create cerebral hypoperfusion. A mitochondrial ATP-sensitive K + channel opener diazoxide (DZ, 5 mg/kg) or its solvent dimethyl sulphoxide (DMSO) were administered i.p. (0.25 ml) on five consecutive days after surgery. Sham-operated animals ( n=18) served as control for the surgery, while nontreated rats were used as control for the treatments. Three months after the onset of cerebral hypoperfusion, the rats were tested in a hippocampus-related learning paradigm, the Morris water maze. Subsequently, the animals were sacrificed and neurons, astrocytes and microglia were labeled with immunocytochemistry in the dorsal hippocampus. DMSO and diazoxide dissolved in DMSO restored cerebral hypoperfusion-related learning dysfunction and prevented cyclooxygenase-2-positive neuron loss in the dentate gyrus. Cerebral hypoperfusion led to reduced astrocyte proliferation, which was not clearly affected by the treatment. Microglia activation was considerably enhanced by cerebral hypoperfusion, which was completely prevented by diazoxide dissolved in DMSO, but not by DMSO alone. We conclude that diazoxide can moderate ischemia-related neuroinflammation by suppressing microglial activation. Furthermore, we suggest that DMSO is a neuroprotective chemical in ischemic conditions, and it must be considerately used as a solvent for water-insoluble compounds in experimental animal models.

A comprehensive approach to visual and functional assessment of experimental vascular lesions in vivo.

The rat carotid injury model is the most widely used model to study the pathophysiology of neointimal hyperplasia as well as the value of novel therapeutic approaches to limit vasoproliferative diseases such as restenosis. For lesion assessment, the current gold standard of histomorphometry neither provides integral insight into the vascular lesion in vivo nor assesses of functional lesion-associated flow alterations and the time course of lesion development. To overcome these limitations, we applied and validated duplex sonography as a novel tool for comprehensive lesions assessment in vivo. Left rat common carotid arteries (CCA) were balloon injured. Duplex sonography was performed in both injured and noninjured CCAs before and up to 14 days postinjury. Sham-operated animals served as controls. The parameters determined were vessel lumen diameter as well as systolic and end-diastolic flow velocity, time-dependent lesion development, and intra- and interobserver variability. Subsequently, the model was applied to validate the therapeutic effect of gene transfer into the vessel wall and compared with histomorphometry. We show that duplex sonography in the experimental carotid injury model allows accurate follow-up of lesion development in vivo with low intra- and interobserver variability. It can be easily adopted to assess the efficacy of therapeutic approaches even with limited technical experience and adds valuable functional data to mere postmortem histomorphometric analysis, thereby closing the gap between experimental approaches and clinical importance of vascular lesions.

Nimodipine attenuates biochemical, behavioral and histopathological alterations induced by acute transient and long-term bilateral common carotid occlusion in rats

Restoration of blood flow to an ischemic brain region is associated with generation of reactive oxygen species with consequent reperfusion injury. Chronic cerebral hypoperfusion induced by permanent occlusion of bilateral common carotid arteries in rats is associated with behavioral and histopathological alterations. Nimodipine, a dihydropyridine calcium channel antagonist, has potent vasodilatory effect on cerebral vessels and increases cerebral blood flow. We analyzed whether nimodipine reduces injury caused by transient forebrain ischemia and long-term cerebral hypoperfusion. Bilateral common carotid occlusion for 30 min followed by 45 min reperfusion resulted in a two-fold increase in lipid peroxidation and superoxide dismutase activity. Nimodipine pretreatment (4 mg/kg, i.p.) brought down these levels by 30 and 23%, respectively. Long-term cerebral hypoperfusion in rats caused a propensity towards anxiety and listlessness (open field paradigm) accompanied by deficits of learning and memory (Morris’ water maze testing). Additionally, histopathological observation in hypoperfused brains revealed reactive changes in the form of perivascular inflammation, gliosis and astrocytosis. Nimodipine treatment significantly alleviated these changes in behavioral and histopathological parameters. Our data confirm the protective role of nimodipine in ischemia reperfusion injury. Moreover, it suggests the beneficial role of nimodipine in cerebrovascular insufficiency states and dementia.

The role of K+ channels in vasorelaxation induced by hypoxia and the modulator effects of lidocaine in the rat carotid artery.

Hypoxia induces vasodilation, partly via the activation of K(+) channels. Lidocaine impairs vasorelaxation mediated by a K(+) channel opener, suggesting that this antiarrhythmic drug may inhibit hypoxia-induced vasodilation mediated by K(+) channels. We designed the current study to determine whether, in the carotid artery, K(+) channels contribute to vasorelaxation in response to hypoxia and whether lidocaine modulates vasorelaxation induced by K(+) channels via pathophysiological and pharmacological stimuli. Rings of rat common carotid artery without endothelium were suspended for isometric force recording. During contraction to phenylephrine, hypoxia-induced vasorelaxation or concentration-response to an adenosine triphosphate-sensitive K(+) channel opener was obtained changing control gas to hypoxic gas and the cumulative addition of levcromakalim, respectively. Hypoxia-induced vasorelaxation was significantly reduced by glibenclamide (5 micro M) but not by iberiotoxin (0.1 micro M), apamin (0.1 micro M), BaCl(2) (10 micro M), or 4-aminopyridine (1 mM). Levcromakalim-induced vasorelaxation was completely abolished by glibenclamide. Lidocaine (10-100 micro M) concentration-dependently inhibited this vasodilation, whereas it did not affect hypoxia-induced vasodilation. These results suggest that adenosine triphosphate-sensitive K(+) channels play a role in hypoxia-induced vasodilation in the rat carotid artery and that lidocaine differentially modulates vasodilation via these channels activated by pathophysiological and pharmacological stimuli. In rat carotid artery, levcromakalim produced vasorelaxation mediated by adenosine triphosphate (ATP)-sensitive K(+) channels, whereas hypoxia induced it partly via these channels. Lidocaine inhibited vasorelaxation induced by an ATP-sensitive K(+) channel opener but not by hypoxia, indicating the differential mechanisms of modulatory effects of this antiarrhythmic drug on vasodilation via ATP-sensitive K(+) channels activated by pathophysiological and pharmacological stimuli.

Experimental Polyvinyl Alcohol Core Coil for a Drug Delivery System

We developed a new type of coil with a polyvinyl alcohol core (PVA-core coil) to absorb and release various types of biologically active materials, for the endovascular treatment of intracranial aneurysms. A 10 mm segment of the PVA-core coil was used in this study. PVAcore coils were immersed in basic fibroblast growth factor (b-FGF) solution. The PVA-core coil, which absorbed b-FGF in the PVA core, was named FGF-core coil. This coil gradually released b-FGF in the solution without b-FGF. In vitro study, FGF-core coils, PVA-core coils and unmodified coils were cultured with fibroblasts (NIH3T3) respectively and their surface was observed with scanning electron microscopy (SEM). In vivo study, each coils were inserted into the rat common carotid artery. Rats were sacrificed and the arterial lumen were histologically examined 14 days and 28 days after coil implantation. Electron microscopy findings demonstrated remarkable cellular adhesion to the surface of the FGF-core coils, while no adhesion to the surface of the PVA-core coils and unmodified coils was found. Histologically, remarkable cellular proliferation and wall thickness like neointimal hyperplasia was demonstrated in the implanted common carotid artery of the FGF-core coil group at 14 days and 28 days. On the other hand, these changes did not occur in PVA-core coil group and unmodified coil group.We suggest that FGF-core coils may be effective to induce fibrotic changes inside cerebral aneurysms.

Geometrical, functional, and histomorphometric adaptation of rat carotid artery in induced hypertension

Acute and long-term (up to 56 days) evolution of geometry, structural properties, vascular smooth muscle (VSM) tone and histomorphometric properties of the rat common carotid arteries under induced hypertension were investigated. Hypertension was induced in 8-week old male Wistar rats by total ligation of the aorta between the two kidneys. Rats were sacrificed 2, 4, 8 and 56 days postsurgery. The arterial wall layers thicken non-uniformly during the adaptation process, the inner layers thicken more in the acute phase of hypertension, whereas the outer layers of the wall are thicker than the inner layers at the end of the adaptation phase. Collagen content in the wall media exhibits a non-linear evolution, with a rapid increase in the acute hypertension phase followed by a slower increase at long-term. The elastin content increase is slight and steady, whereas VSM shows a steady but considerable increase which outdoes the collagen increase in long-term phase. VSM tone increases rapidly in the acute phase of remodelling (0–8 days) and this increase in tone contributes to a considerable increase in arterial compliance in the operating pressure range. At long-term (56 days) VSM tone returns to near control level, but compliance is even further increased, which suggests that at long-term the compliance increase is attributed primarily to structural remodelling.

Derivatised alpha-tocopherol as a CoQ10 carrier in a novel water-soluble formulation.

We have derivatised alpha-tocopherol (vitamin E) to a water-soluble polyoxyethanyl-alpha - tocopheryl sebacate (PTS) and discovered that it formed a non-covalent complex with CoQ10 at a molar ratio of 2:1 (PTS-CoQ10). This complex was water-soluble and remained stable for extended periods of time. After oral delivery of the formulation into rats PTS was hydrolysed to vitamin E and elevated levels of both vitamin E and CoQ10 in blood plasma were detected within 1 h. Thus, this aqueous formulation contains a combination of two potent antioxidants. The formulation's efficacy was tested against ischemic brain damage caused by a transient (8 min) bilateral occlusion of the common carotid arteries in rats. The animals received PTS-CoQ10 by two intraperitoneal injections given immediately after ischemia and 3 h later and the brain damage was assessed up to 12 days post-ischemia. A significant neuroprotection was observed in the CA1 hippocampal region, for example at 12 days approximately 50% of CA1 neurons were still alive in the treated animals versus less than 5% in the non-treated group. Our data is consistent with previously published observations indicating the therapeutic potential of antioxidants for treatments of ischemia/reperfusion injuries and the formulation described here is particularly appropriate for the application in acute conditions, such as stroke or cardiac arrest.

Marked neuropeptide Y-induced contractions via NPY-Y 1 receptor and its desensitization in rat veins

The aim of this study was to investigate neuropeptide Y (NPY)-induced vasoconstrictions in rat blood vessels and which NPY receptor subtype is involved in vasoconstrictions. NPY produced marked contractions in rat common jugular, brachial, portal, femoral and tail veins, and vena cava inferior, whereas it produced little or no contractions in rat common carotid, brachial, femoral and tail arteries, and thoracic and abdominal aortae. The maximal NPY-induced contractions were larger than maximal phenylephrine (PE)-induced contractions in the veins. These NPY-induced contractions were blocked by the Y 1 antagonists, SRL-21, and BIBP3226 but not by the Y 5 antagonist, L-152804. A Y 2 agonist, NPY (13–36), did not produce contractions. RT-PCR showed that NPY-Y 1 was the only receptor subtype in the veins indicating that NPY-induced contractions are mediated through the Y 1 receptor. Pretreatment with NPY showed a rapid and long-lasting desensitization of these contractions. The marked NPY-induced contractions and its desensitization in the veins suggest the physiological relevance of NPY in the venous circulation.

Existence of Functional α1A- and α1D- but No α1B-Adrenoceptor Subtypes in Rat Common Carotid Arteries

Using the cannula inserting method, vasoconstrictor responses to alpha1-adrenoceptor agonists (noradrenaline [NA], phenylephrine [PE] and methoxamine [ME]) and effects of alpha1-adrenoceptor antagonists (WB4101, chloroethylclonidine [CEC] and BMY7378) were investigated in isolated and perfused rat common carotid arteries. The rank order of agonist potency and efficacy was NA = PE > ME. Either WB4101 or BYM7378 inhibited NA- and PE-induced constrictions in a dose-related manner. CEC did not inhibit the NA- and PE-induced responses. The ME-induced responses were also significantly blocked by either WB4101 or BMY7378. From these results, it is concluded that there are functional alpha1A- and alpha1D-adrenoceptor subtypes in rat common carotid arteries, but no functional alpha1B subtype.