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PubMed1994

Three-dimensional studies on the structure of the tissue surrounding the superior mesenteric artery.

The anatomy and topography of tissue surrounding the superior mesenteric artery were examined histopathologically, and the structure surrounding the superior mesenteric artery (SMA) was reconstructed with data from histologic examination and three-dimensional analyses. Specimens were obtained from three autopsy cases without abnormalities, two surgically resected cases of cancer of the pancreatic head, and one autopsy case of cancer of the pancreatic head. The endothelium or basal membrane of blood and lymph vessels were identified immunohistochemically, and the distribution of lymph nodes, blood vessels, lymph vessels, and collagen fibers was determined. The superior mesenteric plexus was found to be a relatively dense structure with a thickness of about 2 mm, composed of collagen fibers and connective tissue, which concentrically enveloped the small arteries, the superior mesenteric artery, nerve bundles, and capillaries. Lymph vessels larger than a few micrometers in diameter were often found outside of the plexus, and this plexus contained no lymph nodes in any sections. The three-dimensional study of the modes of spread along the superior mesenteric artery of pancreatic cancer revealed two types of spread: the tumor extends mainly by neural invasion, and the tumor extends mainly by lymph node metastases. These morphologic features suggest that lymphatic flow in the vicinity of the superior mesenteric artery passes primarily outside of the plexus, and complete excision of lymph nodes close to the superior mesenteric artery with preservation of the superior mesenteric plexus is feasible if there is no neural invasion into retropancreatic tissues.

Biomarkers↗

PubMed1997

Regional vascular and cardiac responses to systemic neuropeptide-Y in normal and diabetic rats.

Diabetes is associated with altered autonomic activity, and both the peripheral and central nervous content of NPY is altered in diabetes suggesting that part of the cardiovascular dysfunction of diabetes may be associated with altered responses to NPY. We evaluated the mean arterial pressure (MAP), heart rate (HR) and regional blood flow (BF) in response to NPY in normal and diabetic rats. Male Wistar rats were made diabetic using streptozotocin and maintained without insulin treatment for 28-30 days. Normal and diabetic animals were anesthetized, the femoral artery cannulated, and flow probes placed around the iliac, renal and superior mesenteric arteries. Dose dependent responses to NPY infusion were determined for MAP, HR and BF. Conductance was calculated from BF/MAP. In normal rats NPY increased the MAP in a dose-dependent fashion but did not alter the HR. NPY decreased the BF in the iliac artery in a dose-dependent fashion while the renal BF was decreased only at the highest dose, and the superior mesenteric BF was not affected. The conductances in all vascular beds were decreased dose dependently. NPY in diabetic rats also increased MAP and did not affect HR. In diabetic rats NPY also decreased BF in iliac and renal arteries but contrastingly increased BF in the superior mesenteric artery. Again conductances in all three vascular beds were decreased by NPY. When comparing diabetic response to NPY to normals we noted that the MAP response was less in the diabetic, but the HR and regional BF were not different. The vascular conductances in response to NPY were attenuated in the diabetic vessels especially the iliac and superior mesenteric. We conclude that systemic NPY increases MAP as a result of decreased vascular conductance and this vasopressive effect of NPY is diminished in diabetics.

Animals↗

PubMed2001

Interobserver variability in the evaluation of chronic mesenteric ischemia with gadolinium-enhanced MR angiography.

RATIONALE AND OBJECTIVES: The purpose of this study was to assess interobserver variability in the interpretation of gadolinium-enhanced magnetic resonance (MR) angiograms of splanchnic vessels in patients suspected of having chronic mesenteric ischemia (CMI). MATERIALS AND METHODS: Two readers blinded to the initial interpretation retrospectively reviewed gadolinium-enhanced MR angiograms obtained for suspected CMI in 26 patients (20 women and six men; age range, 23-77 years; mean age, 61 years) who also underwent conventional angiography. Each reader graded the degree of stenosis based on the percentage diameter reduction of the celiac artery (CA), superior mesenteric artery (SMA), and inferior mesenteric artery (IMA) by using a five-point ordinal scale: 0, no stenosis: 1, mild stenosis (<50%); 2, moderate stenosis (50%-75%); 3, severe stenosis (>75%); 4, occluded artery. Using the conventional angiogram as a reference standard, authors determined sensitivity and specificity for each observer, assigning two thresholds (grades 2 and 3) as significant stenoses. A kappa statistic (kappa) measured interobserver agreement. RESULTS: With grade 2 stenosis used as a threshold, cumulative accuracies for detecting significant stenosis were 0.95 (95% confidence interval, 0.86-0.99) for reader A and 0.97 (0.88-1.0) for reader B. Interobserver agreement for grading proximal splanchnic stenosis was 0.90 for CA, 0.92 for SMA, and 0.48 for IMA. CONCLUSION: Gadolinium-enhanced MR angiography is reproducibly accurate for detection of proximal splanchnic artery stenosis, with good to excellent interobserver agreement.

Adult↗

PubMed1991

Regulation of postprandial mesenteric blood flow in humans: evidence for a cholinergic nervous reflex.

Duplex ultrasound was used to investigate superior mesenteric artery haemodynamics in humans in order to determine the physiological importance of postprandial blood concentrations of cholecystokinin octapeptide (CCK8), gastrin 17, secretin, and glucagon and to study whether a nervous cholinergic reflex mechanism has a role in the postprandial mesenteric blood flow response. Duplex parameters of vessel diameter, mean velocity, and flow volume were determined serially in the basal state and after stimulation. Changes were compared with baseline values. Superior mesenteric artery parameters were significantly increased over baseline values after a liquid test meal, but ingestion of saline did not cause any changes. Hormones infused simultaneously at postprandial concentrations did not change mesenteric blood flow. When they were infused at pharmacological doses, however, a significant increase in flow parameters was observed. Pretreatment with atropine significantly (p less than 0.05) reduced the mesenteric blood flow response to meal stimulation (57%). These data suggest that the four hormones tested are not of quantitative importance in regulating postprandial superior mesenteric artery blood flow. A cholinergic nervous reflex, however, participates in the control of food induced mesenteric artery flow changes.

Adult↗

PubMed1997

Effects of angiotensin II on cardiac function and peripheral vascular structure during compensated heart failure in the rat.

UNLABELLED: The present experiments were designed to test the hypothesis that the activation of the renin-angiotensin system during compensated heart failure may have adverse effects on cardiac function and change the peripheral vascular structure. ANG II (250 ng/kg/min) or saline (0.9% NaCl) were infused in myocardial-infarcted and sham-operated rats. After 2 weeks, cardiac function and peripheral vascular changes were investigated. RESULTS: ANG II infusion reduced baseline cardiac index in sham rats but did not further reduce this index in ANG II-infused MI rats. Total peripheral resistance was similarly increased in ANG II-infused infarcted and sham rats, and also plasma ANG II concentrations were comparable. ANG II elevated systolic blood pressure by approximately 70 mm Hg in sham rats and increased the medial cross-sectional area of the superior mesenteric artery by 33%. However, ANG II infusions in MI rats resulted in only a minor increase in blood pressure, whereas the cross-sectional area of the superior mesenteric artery did not change. ANG II infusion had no effect on vessel dimensions of the resistance arteries of the pulmonary and mesenteric vascular bed of either group. Calculated ED50 and peak pressor response to acute ANG II injections were comparable in all groups, confirming the presence of functionally intact AT1 receptors. The increases in plasma atrial natriuretic peptide (ANP) and nitric oxide (NO) synthase activity (estimated by aortic cyclic GMP concentrations) were higher in ANG II-infused MI rats than in ANG II-infused sham rats. CONCLUSION: ANG II infusion in rats with and without MI has comparable negative effects on cardiac function but has different effects on blood pressure and vascular structure. The concomitant increases in plasma ANP and NO synthase activity in ANG II-infused MI rats suggest that the growth stimulatory and hypertensive actions of ANG II in sham rats may be counter-regulated by activation of inhibitory neurohumoral systems such as ANP or NO in MI rats.

Angiotensin II↗

PubMed2000

Embryology, anatomy, and surgical exposure of the great abdominal vessels.

This article describes the embryology of the abdominal aorta and the anatomic features of its major visceral branches, including the celiac, superior mesenteric, and inferior mesenteric arteries. The common anatomic variants of these visceral vessels also are reviewed. Various operative techniques to gain surgical exposure to these vessels are described.

Aorta, Abdominal↗

PubMed1996

Vasoactivity and immunoreactivity of fish tachykinins in the vascular system of the spiny dogfish.

Tachykinin control of gut blood flow (measured by pulsed Doppler technique), dorsal aortic pressure, and heart rate were studied in unrestrained spiny dogfish Squalus acanthias injected with the elasmobranch tachykinins scyliorhinin I and II (SCY I and SCY II), the trout tachykinins substance P (SP), and neurokinin A (NKA). Effects on somatic vasculature were measured by in vitro perfusion of the isolated tail. SCY I and trout SP produced hypotension due to a general vasodilation. This caused a transient increase in mesenteric blood flow and a prolonged increase in celiac blood flow. SCY II caused an initial hypertension induced by a general vasoconstriction, followed eventually by an elevated flow in both gut arteries due to dilation of the vascular beds. Trout NKA evoked a short-lasting increase in celiac blood flow due to a decrease in vascular resistance, a late decrease in mesenteric flow due to vasoconstriction, and no effect on the somatic vasculature. None of the peptides affected heart rate. The study demonstrates a significant vasoactive function of fish tachykinins in the vascular system of an elasmobranch species and, in addition, the occurrence of tachykinin receptor subtypes. Immunohistochemistry revealed a NKA/SCY II-like peptide in nerve fibers innervating many vessels, including the celiac and the mesenteric arteries, the gastrointestinal canal, and the heart.

Amino Acid Sequence↗

PubMed1994

The pathogenesis of Crohn's disease.

This paper describes a program of research undertaken by the Inflammatory Bowel Disease Study Group at the Royal Free Hospital School of Medicine. The Group has tested the hypothesis that the primary pathological abnormality in Crohn's disease is in the mesenteric blood supply. The first experiments involved microcorrosion resin casting of the arterial supply of specimens of resected intestine affected by Crohn's disease. This revealed severe damage to submucosal blood vessels, even in areas that were not affected macroscopically by Crohn's disease. Resected specimens of bowel were examined after perfusion-fixation: 85% of granulomas were associated with blood vessels, demonstrating that Crohn's disease is a granulomatous vasculitis. Patients with Crohn's disease usually have one or more features of a hypercoagulable state, which may increase the risk of ischemic damage. A model of Crohn's disease was developed in the ferret intestine, by embolizing mesenteric blood vessels using latex particles. Acute embolization results in patchy necrosis of the mucosa, with subsequent recovery. Surgical incision and anastomosis in a previously embolized area results in intense ulceration--suggesting that recurrent Crohn's disease after surgery is due to a second ischemic insult to an already damaged intestine. Finally, electron microscope studies have investigated the mesenteric vascular endothelium associated with granulomata in Crohn's disease. Viral particles have been identified within the vascular endothelium, with the appearance of paramyxoviridae. In situ hybridization and other studies suggest that these particles are measles virus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1985

Prostaglandins and thromboxane outflow from the perfused mesenteric vascular bed in spontaneously hypertensive rats.

To clarify the metabolism of PGE2, prostacyclin (PGI2) and thromboxane A2 (TxA2) in small vessels in spontaneously hypertensive rats (SHR), we removed superior mesenteric vascular beds from 10 week old SHR and age matched normotensive controls (WKY). The mesenteric artery was perfused with Krebs-Henseleit buffer and samples of effluent collected every 15 minutes during 3 hours perfusion for analysis of PGE2, 6-keto-PGF1 alpha (a stable metabolite of PGI2) and TxB2 (a stable metabolite of TxA2) by specific radioimmunoassays. Levels of all three arachidonic acid (AA) metabolites, PGE2, 6-keto-PGF1 alpha and TxB2, in the mesenteric effluent were significantly reduced in SHR as compared to WKY. TxB2 was detected in all samples throughout the perfusion. 6-keto-PGF1 alpha/PGE2 ratios and TxB2/PGE2 ratios were significantly increased in SHR. 6-keto-PGF1 alpha/TxB2 ratios in the first four samples were significantly decreased in SHR as compared to WKY. These data suggest that there may be reduced availability of PG precusor AA and unbalanced synthesis of PGs in small vessels in SHR. Both may have relevance to the development of hypertension in the animals.

Animals↗

PubMed1988

Effect of ischaemia on endothelium-dependent vasodilatation in the isolated rat superior mesenteric artery.

The isolated perfused rat superior mesenteric artery preparation was used to determine whether endothelium-dependent vasodilatation occurs in this vessel, and to test whether impairment of this function may contribute to post-ischaemic mesenteric vasospasm. It was found that vessels preconstricted with noradrenaline responded to optimal concentrations of acetylcholine (3 X 10(-5) M), ADP (2 X 10(-5) M) and to isolated homologous platelets (500,000/mm3) with an 84%, 85% and 37% decrease in mean perfusion resistance, respectively. In preparations treated with collagenase to denude the vessels of endothelium there was a significantly diminished response to acetylcholine and ADP (24% & 23% decrease in resistance, respectively). Platelets, on the other hand, caused a further 34% increase in resistance. A model of mesenteric ischaemia was produced by interrupting perfusate flow through the preparation for intervals of 1 to 4 h. This was associated with morphological evidence of endothelial cell damage and with a progressive decline in the responsiveness to acetylcholine and ADP. After 1 h there was also a significant reduction in the response to platelets. With intervals of ischaemia longer than 2 h platelets caused only further constriction which could be inhibited by the serotonin antagonist, methysergide. This study suggests that an altered response of the endothelium to platelet-derived vasoactive substances may contribute to the post-ischaemic vasospasm encountered during reperfusion.

Acetylcholine↗

PubMed1987

Effect of pH on the inhibition of angiotensin converting activity by enalaprilat in the rat perfused mesenteric vascular bed.

The previous finding that converting enzyme inhibitors (CEIs) potentiate bradykinin (BK), but do not inhibit conversion of angiotensin (ANG) I in isolated vessels, was explored further in the rat perfused mesenteric vascular bed. To investigate whether other peptidases besides angiotensin converting enzyme (ACE) might be involved in CEI-resistant ANG I conversion, synthetic angiotensinogen fragments (1-14, 1-11 and 2-14) were studied. Their vasoconstrictor activities were found to be about 80 times less than that of ANG I, and were not altered by the CEI enalaprilat, indicating that tonin-like enzymes do not play a role in the generation of ANG II by the arterial wall. The hypothesis that BK potentiation by CEI in arteries might be due to a direct effect on the receptors was not supported by the lack of potentiation, by enalaprilat, of the vasorelaxant effect of Lys-Lys-BK (an ACE-resistant BK homologue). Finally, the effect of pH in the perfusing solution on ACE inhibition by enalaprilat was studied. Whereas converting activity decreased with increasing pH in the range 6.8 to 8.1, enalaprilat did not affect the responses to ANG I at pH 7.5 or 7.8, but blocked them at pH 7.1. Our results indicate that arterial ACE shows substrate-specific inhibition and that, at physiological pH, converting activity is resistant to inhibition by CEIs, whose hypotensive action would be due mainly to inhibition of arterial wall kininase activity.

Angiotensin II↗

PubMed1975

Evidence for non-mast cell histamine in the vascular wall.

Histamine has been found biochemically in the mammalian vascular wall. This study was undertaken in an effort to identify the presence of specific histamine-containing cells inwalls of large blood vessels such as femoral artery and vein, brachial artery and vein, mesenteric artery and vein, renal artery and vein, and aorta. Segments of vessels from rats, cats, dogs, sheep, cows, humans and chickens were examined. Sections were prepared from fresh tissue by vibratome, from frozen tissue by cryostat and from freeze-dried and fixed tissues. Mast cells were visualized by staining with acidic toluidine blue and by reaction with orthophthaladehyde to develop histamine fluorescence. Although mast cells were easily identified in preparations such as canine liver, ear and scrotal skin and rat tongue, no such cells were found in any species (except the cow) in any part of the vascular wall. The results indicate that in most species histamine is stored in the vascular wall in a non-mast cell pool which may well be in the smooth muscle cells themselves.

Animals↗

PubMed1993

Isolation and culture of rat superior mesenteric artery smooth muscle cells.

The structure and function of vascular smooth muscle cells have been extensively investigated with the aid of in vitro culture techniques. The majority of studies have utilized aortic tissue as the source of cells. We present here a method for isolating and culturing smooth muscle cells of the rat superior mesenteric artery, an elasto-muscular vessel that is structurally and functionally different from the aorta. Cells were isolated from partially digested explants and characterized by immunochemical and biochemical techniques. Unlike cultured fibroblasts, the cultured cells stained positive for smooth muscle specific actin. The cells also produced laminin and type IV collagen in culture. This method provides a means for the isolation of large numbers of viable smooth muscle cells from the superior mesenteric artery which can be propagated in culture for in vitro study.

Actins↗

PubMed1984

Microcirculatory actions and uses of naturally-occurring (magnesium) and novel synthetic calcium channel blockers.

Synthetic calcium channel blockers (Ca2+ entry blockers or antagonists) have been reported to induce relaxation of smooth muscle which is not thought to be mediated by any specific action(s) on receptor sites. In addition, it has been suggested that Ca2+ channel blockers increases blood flow in a number of organ regions, including mesenteric, femoral, renal, cerebral and coronary vasculatures, via a direct action on vascular tone by inhibiting Ca2+ influx across the vascular smooth muscle membranes. Such information has prompted clinical studies with the use of Ca2+ channel blockers in the treatment of a wide variety of cardiovascular disorders. The questions, to be answered, however, are whether any of the newly-designed channel blockers can actively produce vasodilatation of arterioles and venules in regional microvasculatures, and these synthetic agents are safe and therapeutically effective. In addition, can one design site-specific (e.g., cerebral vs. coronary vasodilator) Ca2+ channel blockers. But, since the body has a natural Ca2+ antagonist, viz., magnesium ions (Mg2+), one must ask whether such divalent cations act as peripheral vasodilators and are effective as therapeutic agents. The studies reviewed herein: compare the effects of several different Ca2+ channel blockers on resistance and capacitance vessels in different regional microvasculatures (i.e., mesenteric, skeletal muscle, pial) within a single species, namely the rat, by high-resolution TV microscopy, and demonstrate the rationale, effects and mechanisms of action of Mg2+ on regional blood vessels. These data show some of the new, novel synthetic Ca2+ channel blockers (i.e., nisoldipine, nitrendipine, nimodipine) can: exert effects on both arterioles and venules in certain vasculatures; be designed to exert a wide range of potencies; and be designed to act selectively at regional microvasculatures. In addition, the data presented are consistent with the hypothesis that Mg2+ exerts a regulatory role in vascular tone, vascular reactivity and vascular resistance. Certain vascular diseases associated with a Mg2+-deficiency appear to be amenable to treatment with Mg2+.

Anesthesia↗

PubMed1979

[Revascularisation of the intestinal arteries from the suprarenal aorta (author's transl)].

Amongst procedures for revascularisation of the intestinal arteries, bypass implanted in the suprarenal aorta by a purely abdominal approach, with section of the right crus of the diaphragm, would appear to be the most satisfactory procedure. For the superior mesenteric, in particular, the pre-pancreatic anterograde course avoids any bending or kinking. Nine patinets undergoing surgery with venous or goretex grafts confirmed the quality of the results obtained by this technique.

Aorta, Abdominal↗

PubMed2002

Mesenteric vein thrombosis triggered by blunt abdominal trauma in a patient with the primary antiphospholipid syndrome.

The antiphospholipid syndrome is defined by the presence of autoimmune antiphospholipid antibodies in serum together with venous, arterial or small-vessel thrombosis and/or morbidity with pregnancy. Superior mesenteric vein thrombosis represents a rare complication associated with this syndrome; triggering events such as surgical procedures, drug administration and anticoagulation withdrawal have been reported. We describe a case of superior mesenteric vein thrombosis triggered by blunt abdominal trauma in a 47-year-old man with the primary antiphospholipid syndrome. It confirms a previous report describing a patient suffering from the catastrophic antiphospholipid syndrome after a fall. This provides evidence, previously unreported, for the possible role of trauma as a precipitating factor leading to thrombosis, even in cases of 'simple' antiphospholipid syndromes. Our patient required extensive small-bowel resection but could be discharged after complete recovery.

Abdominal Injuries↗

PubMed1992

Role of duplex Doppler ultrasound in the assessment of patients with postprandial abdominal pain.

In 10 patients with postprandial abdominal pain thought likely to be the result of mesenteric ischaemia Doppler ultrasound examinations of the superior mesenteric and coeliac arteries were performed both after fasting and a standard meal of 800 kcal. Compared with control values Doppler waveform analysis suggested seven abnormal vessels. Two patients had abnormal fasting superior mesenteric artery waveforms manifested by very high peak systolic velocities together with spectral broadening (one also had evidence of coeliac artery stenosis), and one patient had normal velocities but an abnormal signal and evidence of proximal superior mesenteric stenosis was supported by colour Doppler imaging and confirmed by angiography. Postprandially, two patients showed very high peak systolic and end diastolic velocities in the superior mesenteric artery (one had had a normal fasting waveform signal) and one in the coeliac artery, suggestive of vascular stenosis, while one patient showed a fall in peak systolic velocity. The diagnosis of mesenteric ischaemia in two of these patients was supported by digital subtraction angiography and abdominal computed tomography. Doppler ultrasound may be a useful non-invasive investigation for patients with postprandial abdominal pain that helps to select patients for angiography. Patients with tight vascular stenosis may have abnormal fasting Doppler waveform patterns but in symptomatic patients further information may be obtained after the haemodynamic stress of feeding. Additional information to enhance the diagnostic sensitivity of the test may be obtained by colour Doppler imaging.

Abdominal Pain↗

PubMed2002

Endothelium-independent vasodilator effects of the flavonoid quercetin and its methylated metabolites in rat conductance and resistance arteries.

The flavonoid quercetin is metabolized into isorhamnetin, tamarixetin, and kaempferol, the vascular effects of which are unknown. In the present study, the effects of quercetin and its metabolites were analyzed on isometric tension in isolated rat thoracic and abdominal aorta, in isolated intact and beta-escin-permeabilized iliac arteries, and on perfusion pressure in the isolated mesenteric resistance vascular bed. In noradrenaline-precontracted vessels, the four flavonoids produced a vasodilator effect, which was inversely correlated with the diameter of the vessel studied; i.e., quercetin, isorhamnetin, tamarixetin, and kaempferol were 5-, 25-, 4-, and 6-fold, respectively, more potent in the resistance mesenteric bed (-log IC(50) = 5.35 +/- 0.15, 5.89 +/- 0.11, 5.34 +/- 0.10, and 5.66 +/- 0.06, respectively) than in the thoracic aorta (-log IC(50) = 4.68 +/- 0.08, 4.61 +/- 0.08, 4.73 +/- 0.11, and 4.81 +/- 0.13, respectively; n = 4-6). The vasodilator responses of quercetin and isorhamnetin were not significantly modified after removal of the endothelium in the thoracic aorta or in the mesenteric bed. Furthermore, the guanylate cyclase inhibitor ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; 10(-6) M), the adenylate cyclase inhibitor SQ22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine; 10(-6) M], KCl (40 mM), or ouabain (10(-3) M) had no effect on isorhamnetin-induced vasodilation in the mesenteric bed. In permeabilized iliac arteries stimulated with Ca(2+) (pCa of 5.9), isorhamnetin was also significantly more potent (-log IC(50) = 5.27 +/- 0.15) than quercetin (-log IC(50) = 4.56 +/- 0.15). In conclusion, quercetin and its metabolites showed vasodilator effects with selectivity toward the resistance vessels. These effects are not due to or modulated by endothelial factors and are unrelated to changes in cytosolic Ca(2+).

Animals↗