Arteries Of Pigs Research Articles

Study of possible anatomical arrangement of the vertebral artery in guinea pig

AbstractThe aim of this study was to describe the possible anatomical arrangements of the vertebral artery in guinea pig. The study was carried out on 30 adult English self guinea pigs using corrosion technique. After sacrifice, the vascular network was perfused with saline. Batson’s corrosion casting kit no. 17 © was used as a casting medium. After polymerisation of the medium, the maceration was carried out in KOH solution. We found high variability in the origin of vertebral artery. In 10% of the cases, the left vertebral artery originated independently from the left subclavian artery and in 36.7% of the cases originated by means of a common trunk with some another branches. In 50% of the cases, the left vertebral artery was formed by the fusion of two branches originating from a common trunk with some another branches of the left subclavian artery. In 26.7% of the cases, the right vertebral artery originated independently from the right subclavian artery and in 40% of the cases originated by means of a common trunk with some another branches. Right vertebral artery formed by the fusion of two branches originating independently from the right subclavian artery was present in 20% of the cases. In 13.3% of the cases, the right vertebral artery was formed by the fusion of two branches originating from a common trunk with some another branches of the right subclavian artery.

Effects of Resveratrol on Contractions of the Rat Tail Artery

In 2000, Naderali et. al. reported in Clinical Science (98:537-43) that resveratrol's direct vasorelaxant effect in vitro (on either adrenergic receptor-induced or high potassium-induced vascular smooth muscle contractions) was significantly greater in ring segments cut from mesenteric resistance arteries than from the main uterine conductance artery of female guinea pigs. Since then this important difference has not been confirmed in any other resistance versus conductance arterial tissues, and isolated from the same vasculature perfusing the same organ rather than different vessels perfusing different organs. The most distal and most proximal portions of the notably long ventral tail artery of the laboratory rat are commonly known for their unique structural and functional similarities to other resistance and conductance arteries (respectively) found throughout the rest of the body. Accordingly, we tested for relaxant effects of resveratrol in vitro in adrenergically pre-contracted rings cut from short segments of the distal and proximal portions of the tail artery from male rats. Its half-maximally effective concentration values were essentially identical (25±3 versus 27±3 micromolar) in distal versus proximal segments; results which do not confirm a greater relaxant effect of resveratrol in resistance versus conductance arterial tissues. Therefore, what Naderali et. al. previously observed may have been due to some other property that differed between their mesenteric and uterine arterial preparations. Support: MWU Master's Program.

A structural constitutive model for smooth muscle contraction in biological tissues

A structural constitutive model that characterizes the active and passive responses of biological tissues with smooth muscle cells (SMCs) is proposed. The model is formulated under the assumption that the contractile units in SMCs and the connected collagen fibers are the active tissue component, while the collagen fibers not connected to the SMCs are the passive tissue component. An evolution law describing the deformation of the active tissue component over time is developed based on the sliding filament theory. In this evolution law the contraction force is the sum of a motor force that initiates contraction, a viscous force that describes the actin–myosin filament sliding, and an elastic force that accounts for the deformation of the cross-bridges. The mechanical response of the collagen fibers is governed by the fiber recruitment process: collagen fibers support load and behave as a linear elastic material only after becoming taut. The proposed structural constitutive model is tested with published active and passive, uniaxial and biaxial experimental data on pig arteries.

VEGF Gene Transfer to the Utero-Placental Circulation of Pregnant Guinea Pigs to Enhance Fetal Growth.

In this chapter, we describe a novel method of adenoviral gene transfer to the uterine and radial arteries of pregnant guinea pigs to improve fetal growth. Adenoviruses encoding VEGF-A165 or a reporter gene β-galactosidase were reconstituted in pluronic gel and applied topically to the exposed uterine and radial arteries following laparotomy. Pluronic gel is a thermosensitive gel that is liquid at 4 °C, but becomes solid as soon as it comes in contact with body temperature. It thereby acts as a slow-release vehicle for viral vectors to the target tissue and also facilitates closer contact of the viruses with the host tissue. Our studies have shown that adenoviral gene delivery using pluronic gel resulted in the highest transduction efficiency compared to intra-arterial administration or external administration in PBS as a vehicle, when measured by X-gal staining, immunohistochemistry, or Western blotting.

Adaptations of the endothelin system after exercise training in a porcine model of ischemic heart disease.

To the test the hypothesis that exercise training would increase endothelin-mediated vasoconstriction in collateral-dependent arteries via enhanced contribution of ET(A). An ameroid constrictor was surgically placed around the proximal LCX artery to induce gradual occlusion in Yucatan miniature swine. Eight weeks postoperatively, pigs were randomized into sedentary or exercise-training (treadmill; 5 days/week; 14 weeks) groups. Subsequently, arteries (~150 μm diameter) were isolated from collateral-dependent and nonoccluded myocardial regions and studied. Following exercise training, ET-1-mediated contraction was significantly enhanced in collateral-dependent arteries. Exercise training induced a disproportionate increase in the ET(A) contribution to the ET-1 contractile response in collateral-dependent arteries, with negligible contributions by ET(B). In collateral-dependent arteries of sedentary pigs, inhibition of ET(A) or ET(B) did not significantly alter ET-1 contractile responses in collateral-dependent arteries, suggesting compensation by the functionally active receptor. These adaptations occurred without significant changes in ET(A), ET(B), or ECE mRNA levels but with significant exercise-training-induced elevations in endothelin levels in both nonoccluded and collateral-dependent myocardial regions. Taken together, these data reveal differential adaptive responses in collateral-dependent arteries based upon physical activity level. ET(A) and ET(B) appear to compensate for one another to maintain contraction in sedentary pigs, whereas exercise-training favors enhanced contribution of ET(A).

Development of biodegradable radiopaque microsphere for arterial embolization-a pig study.

To develop a new type of calibrated, biodegradable, and imaging detectable microsphere and evaluated its embolization safety and efficacy on pig's liver and spleen. Six kinds of pharmaceutical excipient were combined and atomized to form our microsphere. Twenty-four male Lanyu pigs weighing 25-30 kg were used. The arteries of spleen and liver were embolized with Gelfoam, Embosphere, or our microsphere. The serum biochemical tests, computed tomography (CT), liver perfusion scan, and tissue microscopy examination were done to evaluate the safety and efficacy of embolization. Radiopaque microspheres with a size ranging from 300 to 400 μm were produced. Embolization of hepatic and splenic artery of pigs with our microsphere significantly reduced the blood flow of liver and resulted in splenic infarction. The follow-up CT imaging and the microscopic examination showed intraarterial degradation of Gelfoam and microsphere. The blood tests demonstrated insignificant changes with regards to liver and renal functions. Our microspheres, with the unique characteristics, can be used for transcatheter arterial embolization with effects equivalent to or better than Gelfoam and Embosphere in pigs.

A Pig Model of Ischemic Mitral Regurgitation Induced by Mitral Chordae Tendinae Rupture and Implantation of an Ameroid Constrictor

A miniature pig model of ischemic mitral regurgitation (IMR) was developed by posterior mitral chordae tendinae rupture and implantation of an ameroid constrictor. A 2.5-mm ameroid constrictor was placed around the left circumflex coronary artery (LCX) of male Tibetan miniature pigs to induce ischemia, while the posterior mitral chordae tendinae was also ruptured. X-ray coronary angiography, ECG analysis, echocardiography, and magnetic resonance imaging (MRI) were used to evaluate heart structure and function in pigs at baseline and one, two, four and eight weeks after the operation. Blood velocity of the mitral regurgitation was found to be between medium and high levels. Angiographic analyses revealed that the LCX closure was 10–20% at one week, 30–40% at two weeks and 90–100% at four weeks subsequent ameroid constrictor implantation. ECG analysis highlighted an increase in the diameter of the left atria (LA) at two weeks post-operation as well as ischemic changes in the left ventricle (LV) and LA wall at four weeks post-operation. Echocardiography and MRI further detected a gradual increase in LA and LV volumes from two weeks post-operation. LV end diastolic and systolic volumes as well as LA end diastolic and systolic volume were also significantly higher in pig hearts post-operation when compared to baseline. Pathological changes were observed in the heart, which included scar tissue in the ischemic central area of the LV. Transmission electron microscopy highlighted the presence of contraction bands and edema surrounding the ischemia area, including inflammatory cell infiltration within the ischemic area. We have developed a pig model of IMR using the posterior mitral chordae tendineae rupture technique and implantation of an ameroid constrictor. The pathological features of this pig IMR model were found to mimic the natural history and progression of IMR in patients.

Helical-centreline (BioMimics 3D) stent offers long term patency protection in patients with femoropopliteal disease

Arterial stents are subject to obstruction and failure by intimal hyperplasia (IH). Arterial curvature is physiologically commonly non-planar, or helical, encouraging us to develop a nitinol, self-expanding, bare-metal, helical-centreline stent. On implantation in the common carotid arteries of healthy pigs, this deformed the vessels helically, generating swirling and mixing of intraluminal flow and (compared with findings with a straight-centreline stent) suppressed the development of IH1. Encouraged by these findings, a prospective, randomised, controlled trial was conducted, involving 76 patients, randomised 2:1, undergoing femoropopliteal artery intervention (patients were implanted with the BioMimics 3D (n=50) helical-centreline stent and control subjects were treated with a straight-centreline stent, primarily the Bard LifeStent (24/26 cases). At two years, two key findings were the Kaplan Meier (KM) survival estimate of freedom from loss of primary patency of 72% for BioMimics 3D subjects, versus 55% for the control group (p=0.0497 by log-rank test). Secondly, there was no decrease in the KM estimate of freedom from clinically driven target lesion re-vascularisation (CDTLR) in the BioMimics 3D arm between 12 and 24 months, compared to a decrease of 16% (92% at 12 months and 76% at 24 months) in the control arm. Enhanced wall shear and possibly improved blood-wall mass transport, including of oxygen, may explain the longer-term patency protective effect seen with the BioMimics 3D stent. (1J R Soc Interface, 2013, Vol:10, 1742-5689)

Stem cell factor gene transfer improves cardiac function after myocardial infarction in swine.

Stem cell factor (SCF), a ligand of the c-kit receptor, is a critical cytokine, which contributes to cell migration, proliferation, and survival. It has been shown that SCF expression increases after myocardial infarction (MI) and may be involved in cardiac repair. The aim of this study was to determine whether gene transfer of membrane-bound human SCF improves cardiac function in a large animal model of MI. A transmural MI was created by implanting an embolic coil in the left anterior descending artery in Yorkshire pigs. One week after the MI, the pigs received direct intramyocardial injections of either a recombinant adenovirus encoding for SCF (Ad.SCF, n=9) or β-gal (Ad.β-gal, n=6) into the infarct border area. At 3 months post-MI, ejection fraction increased by 12% relative to baseline after Ad.SCF therapy, whereas it decreased by 4.2% (P=0.004) in pigs treated with Ad.β-gal. Preload-recruitable stroke work was significantly higher in pigs after SCF treatment (Ad.SCF, 55.5±11.6 mm Hg versus Ad.β-gal, 31.6±12.6 mm Hg, P=0.005), indicating enhanced cardiac function. Histological analyses confirmed the recruitment of c-kit(+) cells as well as a reduced degree of apoptosis 1 week after Ad.SCF injection. In addition, increased capillary density compared with pigs treated with Ad.β-gal was found at 3 months and suggests an angiogenic role of SCF. Local overexpression of SCF post-MI induces the recruitment of c-kit(+) cells at the infarct border area acutely. In the chronic stages, SCF gene transfer was associated with improved cardiac function in a preclinical model of ischemic cardiomyopathy.

Exercise Training‐Induced Adaptations in Mediators of Sustained Endothelium‐Dependent Coronary Artery Relaxation in a Porcine Model of Ischemic Heart Disease

The aim of this study was to test the hypothesis that exercise training enhances sustained relaxation to persistent endothelium-dependent vasodilator exposure via increased nitric oxide contribution in small coronary arteries of control and ischemic hearts. Yucatan swine were designated to a control group or a group in which an ameroid constrictor was placed around the proximal LCX. Subsequently, pigs from both groups were assigned to exercise (five days/week; 16 weeks) or SED regimens. Coronary arteries (~100-350 μm) were isolated from control pigs and from both nonoccluded and collateral-dependent regions of chronically-occluded hearts. In arteries from control pigs, training significantly enhanced relaxation responses to increasing concentrations of bradykinin (10(-10) -10(-7) M) and sustained relaxation to a single bradykinin concentration (30 nM), which were abolished by NOS inhibition. Training also significantly prolonged bradykinin-mediated relaxation in collateral-dependent arteries of occluded pigs, which was associated with more persistent increases in endothelial cellular Ca(2+) levels, and reversed with NOS inhibition. Protein levels for eNOS and p-eNOS-(Ser1179), but not caveolin-1, Hsp90, or Akt, were significantly increased with occlusion, independent of training state. Exercise training enhances sustained relaxation to endothelium-dependent agonist stimulation in small arteries of control and ischemic hearts by enhanced nitric oxide contribution and endothelial Ca(2+) responses.

"Permissive hypoventilation" in a swine model of hemorrhagic shock.

Many penetrating trauma patients in severe hemorrhagic shock receive positive pressure ventilation (PPV) upon transport to definitive care, either by intubation (INT) or bag-valve mask (BVM). Using a swine hemorrhagic shock model that simulates penetrating trauma, we proposed that severely injured patients may have better outcomes with "permissive hypoventilation," where manual breaths are not given and oxygen is administrated passively via face mask (FM). We hypothesized that PPV has harmful physiologic effects in severe low-flow states and that permissive hypoventilation would result in better outcomes. The carotid arteries of Yorkshire pigs were cannulated with a 14-gauge catheter. One group of animals (n = 6) was intubated and manually ventilated, a second received PPV via BVM (n = 7), and a third group received 100% oxygen via FM (n = 6). After placement of a Swan-Ganz catheter, the carotid catheters were opened, and the animals were exsanguinated. The primary end point was time until death. Secondary end points included central venous pressure, cardiac output, lactate levels, serum creatinine, CO2 levels, and pH measured in 10-minute intervals. Average survival time in the FM group (50.0 minutes) was not different from the INT (51.1 minutes) and BVM groups (48.5 minutes) (p = 0.84). Central venous pressure was higher in the FM group as compared with the INT 10 minutes into the shock phase (8.3 mm Hg vs. 5.2 mm Hg, p = 0.04). Drop in cardiac output (p < 0.001) and increase in lactate (p < 0.05) was worse in both PPV groups throughout the shock phase. Creatinine levels were higher in both PPV groups (p = 0.04). The FM group was more hypercarbic and acidotic than the two PPV groups during the shock phase (p < 0.001). Although permissive hypoventilation leads to respiratory acidosis, it results in less hemodynamic suppression and better perfusion of vital organs. In severely injured penetrating trauma patients, consideration should be given to immediate transportation without PPV.

A Novel High Nitrogen Nickel-free Coronary Stents System: Evaluation in a Porcine Model

ObjectiveTo study the safety of the novel high nitrogen nickel-free austenitic stainless steel bare metal stents (BMS) in a recognized porcine coronary model and to select a better grid structure of it. MethodsThree types of stents were randomly implanted in different coronary arteries of the same pig: 316L stainless steel BMS (316L-BMS) (n=12), novel high nitrogen nickel-free stents Grid A (NF-A-BMS) (n=12) and novel high nitrogen nickel-free stents Grid B (NF-B-BMS) (n=12). In total, eighteen animals underwent successful random placement of 36 oversized stents in the coronary arteries. Coronary angiography was performed after 36 d of stents implantation. Nine animals were respectively sacrificed after 14 d and 36 d for histomorphologic analysis. ResultsQuantitative coronary angiography (QCA) showed similar luminal loss (LL) in the three groups: (0.21±0.17) mm for 316L-BMS, (0.16±0.12) mm for NF-A-BMS, (0.24±0.15) mm for NF-B-BMS (P>0.05). Histomorphomeric analysis after 15 d and 36 d revealed that there was also no significant difference among the three groups in neointimal area (NA) with similar injury scores respectively. High magnification histomorphologic examination showed similar inflammation scores in the three groups, but NF-A-BMS group had poorer endothelialization scores compared with NF-B-BMS group, 2.00±0.63 vs. 2.83±0.41 (P=0.015) at 15 d, which also could be proved by the scanning electron microscope. However, the difference could not been observed at 36 d. ConclusionsThe novel NF-BMS showed similar safety as 316L-BMS during the short-term study. NF-B-BMS had better endothelialization than NF-A-BMS and this may owe to the specific strut units.

Near-infrared fluorescence laparoscopy of the cystic duct and artery in pigs: performance of a preclinical dye.

Near-infrared fluorescence laparoscopy after intravenous indocyanine green (ICG) administration has been proposed as a promising surgical imaging technique for real-time visualization of the extrahepatic bile ducts and arteries in clinical laparoscopic cholecystectomies. However, optimization of this new technique with respect to the imaging system combined with the fluorophore is desirable. The performance of a preclinical near-infrared dye, CW800-CA, was compared with that of ICG for near-infrared fluorescence laparoscopy of the cystic duct and artery in pigs. Laparoscopic cholecystectomy was performed in six pigs (average weight, 35 kg) using a commercially available laparoscopic fluorescence imaging system. The fluorophores CW800-CA and ICG (both 800 nm fluorescent dyes) were administered by intravenous injection in four and two pigs, respectively. CW800-CA was administered in three different doses (consecutively 0.25, 1, and 3 mg); ICG was intravenously injected (2.5 mg) for comparison. Intraoperative recognition of the biliary structures was recorded at set time points. The target-to-background ratio was determined to quantify the fluorescence signal of the designated tissues. A clinically proven dose of 2.5 mg of ICG resulted in a successful fluorescence delineation of both the cystic duct and artery. In the CW800-CA-injected pigs a clear visualization of the cystic duct and artery was obtained after administration of 3 mg of CW800-CA. Time from injection until fluorescence identification of the cystic duct was reduced when CW800-CA was used compared with ICG (11.5 minutes versus 21.5 minutes, respectively). CW800-CA provided clearer illumination of the cystic artery, in terms of target-to-background ratio. As well as ICG, CW800-CA can be applied for fluorescence identification of the cystic artery and duct using a commercially available laparoscopic fluorescence imaging system. Fluorescence cholangiography of the cystic duct can be obtained earlier after intravenous injection of CW800-CA, compared with ICG. These findings increase the possibilities of use and of optimization of this imaging technique.

The Use of Doppler/Power Doppler Ultrasound and Angiography for the Evaluation of Cutaneous Perforators in the Thigh and Lumbar-Sacral Region in Pigs

Introduction: Highlighting perforating cutaneous arteries in pig, by imaging methods, is of special importance, for detecting local and regional vascular flaps with perforating pressure source, in reconstructive surgery. However there is a high degree of variability in terms of their anatomical availability.

Ophtalmic Artery Microcatheterization for Research Purposes in Pigs. A Technical Note

ABSTRACTPurpose: To describe a technique for micro catheterization of the external ophthalmic artery (EO) in pigs for investigational and training purposes. Methods: Carotid angiography was performed in seven male domestic pigs. The external ophthalmic artery was reached with a microcatheter in order to administer a neoplastic drug in the eye. Results: The external ophthalmic artery could be found arising from the infraorbital (IO) artery in the bend of the internal maxillary (IM) artery. It could be reached in every animal. Conclusion: Following anatomic landmarks of the external carotid (EC) artery the ophthalmic artery can be easily reached and catheterized for training and investigational purposes.

Intimal hyperplasia following implantation of helical-centreline and straight-centreline stents in common carotid arteries in healthy pigs: influence of intraluminal flow

Intimal hyperplasia following implantation of helical-centreline and straight-centreline stents in common carotid arteries in healthy pigs: influence of intraluminal flow

Paclitaxel coating on the terminal portion of hemodialysis grafts effectively suppresses neointimal hyperplasia in a porcine model

The local delivery of paclitaxel onto a graft has been reported to prevent neointimal hyperplasia. Because more than half of vascular stenoses occur within 3 cm of the venous anastomosis, this study tested the effectiveness of a paclitaxel coating restricted to both ends of the expanded polytetrafluoroethylene (ePTFE) graft to reduce the amount of drug delivered. Both ends of ePTFE grafts were coated with paclitaxel at a dose of 0.58 μg/mm(2); the total amount of paclitaxel per graft was 0.66 mg. Paclitaxel-coated hemodialysis grafts 15 cm in length were surgically implanted between the common carotid artery and external jugular vein in female Landrace pigs. The animals were sacrificed 6 weeks after graft placement. Cross sections of the anastomosis sites were analyzed histomorphometrically to measure the ratio of neointimal hyperplasia to the graft area (H/G ratio) and the percentage of luminal stenosis. The experimental results were compared between grafts coated with paclitaxel at the ends only (n = 8), grafts coated over the entire length (n = 6), and uncoated control grafts (n = 6). The mean ± standard error values of the H/G ratios for the arterial anastomosis were 0.82 ± 0.13 (control), 0.41 ± 0.09 (terminal coating), and 0.21 ± 0.04 (whole coating). The values for the venous anastomosis were 0.82 ± 0.12 (control), 0.39 ± 0.11 (terminal coating), and 0.12 ± 0.03 (whole coating). Compared with the uncoated grafts, neointimal hyperplasia was suppressed effectively in the vascular grafts coated terminally with paclitaxel (artery, P = 050; vein, P < .001). However, the suppressive effect was less than that of grafts coated with paclitaxel over the entire length. The percentages of luminal stenosis showed similar tendency to the H/G ratios. Despite a reduced amount of the drug, paclitaxel coating applied to both ends of the ePTFE hemodialysis grafts effectively suppressed neointimal hyperplasia at the sites of anastomosis.

Morphologic expression of the left coronary artery in pigs. An approach in relation to human heart.

Introduction In spite of its importance as an experimental model, the information on the left coronary artery in pigs is sparse. Objective To determine the morphologic features of the left coronary artery in pigs. Methods We evaluated 158 pig hearts. The left coronary artery was perfused with synthetic resin after their ostia had been catheterized. Diameters and courses of the vascular beds were measured with an electronic caliper (Mitutoyo®). Results The diameter of left coronary artery was 6.98 ± 1.56 mm and its length was 3.51±0.99 mm. It was found to end up by bifurcating itself into the anterior interventricular artery and the circumflex artery in 79% of the cases, and by trifurcating in 21% of the cases, with the presence of the diagonal artery. The anterior interventricular artery ended up at the apex in 79.7% of the cases, and the circumflex artery at the posterior aspect of the left ventricle in 64% of the case, this artery never reached the posterior interventricular sulcus. An anastomosis between the terminal branches of the anterior interventricular artery and the posterior interventricular artery was found in 7.6% of the specimens. The antero-superior branch of the anterior interventricular artery occurred in 89.9% of the hearts. A left marginal branch was observed in 87.9% of the cases with a diameter of 2.25±0.55 mm. Conclusion Compared with humans, pigs have shorter left coronary artery trunks and branches; even the circumflex artery never reaches the posterior interventricular sulcus. Our findings are useful for the design of experimental hemodynamic and procedural models.

Morphologic Expression of the Left Coronary Artery in Pigs. An approach in relation to human heart.

Morphologic Expression of the Left Coronary Artery in Pigs. An approach in relation to human heart.

EPA-0717 – Effects of asenapine on endothelial functions and cardiac cell survive

Bipolar patients have an increased risk of cardiovascular diseases for lifestyle habits and the use of antipsychotics that correlates with endothelial dysfunctions, in particular the decrease of eNOS activity and plasma NO levels. We aimed to examine the effects of the new atypical antipsychotic Asenapine on NO release and oxidative stress in porcine coronary endothelial cells (CEC). NO production was measured in CEC isolated from coronary arteries of pigs and plated in 0.1% gelatin-coated dishes with starvation medium overnight at 37 °C with 5% CO 2 . Cells were treated with asenapine 10 pM-100 μM and asenapine+inhibitors. Oxidative stress was generated with 200 μM hydrogen peroxide in the presence of asenapine for 15 min. The cells undergoing apoptosis were measured and proteins extracted from cell lysates were quantified and used for electrophoresis and immunoblotting studies. Asenapine increased NO release in CEC in a time-dependent way (p<0.05) by the phosphorylation of eNOS and plateau was reached at 120s stimulation; no effect was observed on iNOS activation. The association of asenapine and inhibitors suggested the involvement of cAMP/PKA, PLC, p38MAPK, PI3K and ERK1/2 in the intracellular signaling and the β 2 adrenergic receptors-related pathway. Data were confirmed by Western blot analysis. Pre-treatment of CEC with asenapine prevented cell death and mitochondrial membrane potential collapse caused by hydrogen peroxide (p<0.05) and counteracted the activation of apoptotic markers. Asenapine could play a protective role on endothelial function and cardiac cell survival, reducing the risk of cardiovascular disease in maniac patients.