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PubMed1992

Sonographic diagnosis of intestinal malrotation in infants: importance of the relative positions of the superior mesenteric vein and artery.

OBJECTIVE: An abnormal relative position of the superior mesenteric vein and artery can be present in patients with intestinal malrotation. We undertook this retrospective study to see how often we could determine the relative position of these vessels on abdominal sonograms in infants and how often abnormal position of the vessels was associated with malrotation. MATERIALS AND METHODS: We reviewed the radiology files and medical records of 337 infants with vomiting who were referred for sonography because of possible pyloric stenosis. We used sonograms and written reports to determine the position of the superior mesenteric vessels. The position was considered normal when the superior mesenteric vein was to the right of the superior mesenteric artery on transverse sonograms. The position was considered abnormal when the vein was directly ventral to the artery or when the vein was to the left of the artery. Sonographic findings were compared with results of upper gastrointestinal series when possible and with clinical outcome. RESULTS: The relative positions of the superior mesenteric vein and artery were evident in 249 (74%) of the 337 patients. Abnormal orientation of the mesenteric vessels was detected in nine patients. In five patients, the superior mesenteric vein was located to the left of the artery, and all five had intestinal malrotation. In four patients, the superior mesenteric vein was directly ventral to the artery, and one of these had malrotation. CONCLUSION: Sonographic assessment of the relative positions of the mesenteric artery and vein is an important adjunct in the examination of infants with suspected pyloric stenosis. Patients in whom sonograms show an abnormal position of the vessels should have further examination to detect malrotation.

Congenital Abnormalities↗
PubMed1992

The resistance of some rat cerebral arteries to the vasorelaxant effect of cromakalim and other K+ channel openers.

1. Cromakalim (0.01-30 microM) and sodium nitroprusside (SNP, 0.01-100 microM) were tested for their ability to relax a number of pre-contracted small arteries (approximate diameter 200-700 microM at 100 mmHg) from the rat, rabbit and guinea-pig. 2. In the rat, SNP (0.01-100 microM) caused near maximal relaxation in all vessels studied including the middle cerebral, anterior cerebellar, basilar, mesenteric and renal arteries. Cromakalim (0.01-30 microM) relaxed pre-contracted mesenteric and renal arteries but was only a weak relaxant of all the rat cerebral arteries with the exception of the basilar artery. Similar experiments using mesenteric and cerebral vessels from the rabbit and guinea-pig showed cromakalim could relax pre-contracted vessels in a concentration-dependent manner. 3. Two other K+ channel openers, nicorandil and pinacidil, were also tested for their ability to relax rat cerebral arteries. Nicorandil (0.01-100 microM) was ineffective in the rat anterior cerebellar artery at concentrations up to 100 microM. Pinacidil (0.01-100 microM) caused significant vasorelaxation, although high concentrations were required (greater than 10 microM) and the response was insensitive to the effects of glibenclamide (3 microM). 4. Electrophysiological experiments with the rat anterior cerebellar artery showed that cromakalim (up to 30 microM) failed to influence the resting membrane potential of impaled single smooth muscle cells. 5. The results showed that some rat small cerebral arteries were resistant to the effects of K+ channel openers including cromakalim, pinacidil and nicorandil. This is peculiar to this vascular tree since the same vessels from other species do not exhibit the same behaviour. Such a phenomenon could result from a lack of K+ channels opened by cromakalim in rat cerebral arteries.

Acetylcholine↗
PubMed1988

Iatrogenic superior mesenteric arteriovenous fistula. Report of a case and review of the literature.

Bowel resection can result in the formation of an arteriovenous fistula at the point of intersection of the feeding vessels. Iatrogenic arteriovenous fistula of the superior mesenteric vessels is rare, with only 11 cases reported in the English language literature. We report a case after small bowel resection, which was done because of adhesions from a laparoscopic sterilization. An anatomic classification of the fistulas into H and U types is suggested, with its significance for management. A review of the literature is included.

Arteriovenous Fistula↗
PubMed1996

Effect of terlipressin on in vitro vascular hyporeactivity of portal hypertensive rats.

BACKGROUND/AIMS: Isolated vessels of portal hypertensive rats exhibit decreased responsiveness to vasoconstrictors. The vasopressin analogue terlipressin is used in the treatment of portal hypertension since it is known to reduce portal pressure, an effect that is thought to arise from splanchnic vasoconstriction via stimulation of vasoconstrictor V1 receptors. This study assessed the effect of terlipressin on the in vitro vascular reactivity of portal hypertensive rats to the alpha-adrenoceptor agonist methoxamine. METHODS: Portal hypertension was produced by portal vein ligation. Sham-operated rats served as controls. In isolated perfused mesenteric arteries of portal vein ligated and sham-operated rats pressor responses to methoxamine (3 nmol-3 mumol) were determined in the absence and presence of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME; 100 microM), terlipressin or the selective V2 receptor agonist desmopressin (each 0.5 microM). In addition, the direct pressor properties of terlipressin (3 pmol-100 nmol) were compared to arginine vasopressin (3 pmol-1 nmol) in vessels of normal rats. RESULTS: Mesenteric vessels of portal vein ligated rats were markedly hyporeactive to methoxamine, even in the presence of L-NAME. Terlipressin alone reduced and in combination with L-NAME abolished the difference in reactivity to methoxamine between the portal vein ligated and sham-operated groups, while desmopressin was ineffective. Arginine vasopressin potently contracted vessels of normal rats with a threshold dose of 10 pmol and was maximally effective at 300 pmol. In contrast, terlipressin failed to produce pressor responses up to 100 nmol. CONCLUSIONS: Hyporeactivity of mesenteric vessels of portal vein ligated rats to methoxamine is predominantly independent of nitric oxide. Terlipressin alone ameliorates and in combination with L-NAME abolishes the hyporesponsiveness to methoxamine presumably by inhibiting the nitric oxide-independent mechanism that underlies the reduced responsiveness to methoxamine in portal hypertension. This effect of terlipressin appears to be independent of stimulation of V2 as well as vasoconstrictor V1 receptors.

Acetylcholine↗
PubMed2002

[The activity of angiotensin converting enzyme in vascular mesenteric bed of rats poisoned with lead and cadmium].

Heavy metals can increase the arterial blood pressure by influencing the endothelial renin-angiotensin system. The aim of this study was to determine the effect of single and combined exposure to lead and cadmium at hypertensive doses on the tissue renin-angiotensin system in rats. An attempt was made to assay the induced synthesis of angiotensin II (AII) in the isolated mesenteric rat bed, as well as the reactivity of vessels to AII and norepinephrine used before and after infusion of angiotensin receptor blocker. Angiotensin converting enzyme (ACE), used in infusion, induced slight increase in perfusion pressure only in mesenteric vessels of cadmium poisoned rats. In this group, AII given during ACE infusion induced slightly stronger vasoconstriction than in other groups of rats, and losartan, used in infusion totally eliminated the pressor effect of AII. Therefore, the share of endothelial renin-angiotensin system in the regulation of vessel resistance was greater than in mesenteric bed of lead-poisoned rats or controls. It is likely that the effect of ACE inhibitors and blockers of the AII receptors may be slightly stronger in persons with arterial hypertension exposed to cadmium than in non-exposed patients.

Animals↗
PubMed2004

Acute and chronic captopril, but not prazosin or nifedipine, normalize alterations in adrenergic intracellular Ca2+ handling observed in the mesenteric arterial tree of spontaneously hypertensive rats.

The effect of hypertension and acute (36-h) or chronic (from age 6 to 16 weeks) antihypertensive treatment with prazosin (2 mg kg(-1) per day), nifedipine (50 mg kg(-1) per day), or captopril (50 mg kg(-1) per day) on Ca2+ mobilization due to alpha1-adrenoceptor activation was analyzed in functional studies using arterial rings [four conductance/distributing vessels: aorta, main mesenteric, iliac, and tail arteries and two resistance vessels; first and second small mesenteric artery branches obtained from spontaneously hypertensive rats (SHR, 6 and 16 weeks old) and age-matched Wistar Kyoto rats (WKY)]. Maximal response to noradrenaline in the presence of extracellular Ca2+ is not affected by hypertension or by the antihypertensive treatment. The extracellular Ca2+-independent contractile responses increased with age in iliac, tail, and small mesenteric arteries (SMA) and were further increased in SHR in SMA from both young and adult animals and in the main mesenteric artery of adult SHR. In main mesenteric artery, this increased contraction in SHR was associated with a higher increase in cytosolic [Ca2+] mobilized by noradrenaline without changes in the total stored Ca2+. Acute or chronic treatment with captopril abolished the differences observed between WKY and SHR in the noradrenaline-induced contraction in mesenteric arteries loaded in Ca2+-free medium. In contrast, animals acutely treated with prazosin or chronically treated with either prazosin or nifedipine exhibit the same differences in Ca2+ handling than untreated rats. In conclusion, these differences are not a consequence of increased blood pressure but precede it and can only be normalized by inhibition of the rennin-angiotensin system.

Adrenergic alpha-Antagonists↗
PubMed1979

Mechanical and morphological properties of arterial resistance vessels in young and old spontaneously hypertensive rats.

We studied alterations in structural and mechanical properties of mesenteric arterial resistance vessels from young (6-week) and old (50-week) spontaneously hypertensive (SHR)and matched normotensive Wistar-Kyoto (WKY) rats. Emphasis was placed upon relating the active tension capabilities of these vessels to their smooth muscle cell content. Cylindrical segments, 0.7 mm long with internal diameters of 150 micrometer, were mounted in a myograph capable of recording circumferential vessel wall tension and dimensions. Comparisons of vessel morphology and mechanics were performed at a normalized internal circumference, L1,where active tension (delta T1) is near maximum. Arterial wall and medial hypertrophy were observed in young and old SHR. Since the percent smooth muscle cells within the media for SHR was similar to that of WKY, both increased smooth muscle cell and connective tissue content account for the medial hypertrophy. These differences in SHR vessels were reflected directly in their passive and active mechanical properties. Fully relaxed vessels from SHR were less compliant, and upon activation at L1 (high potassium depolarization), delta T1 was not different for young SHR and WKY, but values for old SHR were 35% greater (P less than 0.05) than for WKY. When relating the active force generation of the vessel to the actual smooth muscle cell area, values for smooth muscle cell stress (force/area) were similar for SHR and WKY at both ages. In addition, similarities were observed for active dynamic mechanical measurements of Young's modulus and half response time. Genetic hypertension in rats therefore appears to be associated with the development of increased vessel contractility determined by a greater number of smooth muscle cells which possess contractile properties similar to those of normotensive vessels.

Animals↗
PubMed2006

Progression of coronary and mesenteric vascular dysfunction in Zucker obese and Zucker diabetic fatty rats.

We investigated the progression of vascular dysfunction associated with the metabolic syndrome with and without hyperglycemia in lean, Zucker obese, and Zucker diabetic fatty (ZDF) rats. Responses of aorta and small coronary and mesenteric arteries were measured to endothelium-dependent and -independent vasodilators. Indices of oxidative stress were increased in serum from ZDF rats throughout the study, whereas values were increased in Zucker obese rats later in the study [thiobarbituric acid reactive substances: 0.45 +/- 0.02, 0.59 +/- 0.03 (P < 0.05), and 0.58 +/- 0.03 (P < 0.05) mug/ml in serum from 28- to 40-wk-old lean, Zucker obese, and ZDF rats, respectively]. Acetylcholine (ACh)-induced relaxation was not altered in vessels from lean animals from 8-40 wk. ACh-induced relaxation was nearly abolished in coronary arteries from 28- to 36-wk-old Zucker obese rats and by 16-36 wk in ZDF rats and was attenuated in aorta and mesenteric vessels from ZDF rats [%relaxation to 10 muM ACh: 72.2 +/- 7.1, 17.9 +/- 5.9 (P < 0.05), and 23.0 +/- 4.5 (P < 0.05) in coronary vessels; and 67.9 +/- 9.2, 50.1 +/- 5.5, and 42.3 +/- 4.7 (P < 0.05) in mesenteric vessels from 28- to 40-wk-old lean, Zucker obese, and ZDF rats, respectively]. The attenuated ACh-induced relaxation was improved when vessels were incubated with tiron, suggesting superoxide as a mechanism of endothelial dysfunction. Sodium nitroprusside-induced relaxation was not altered in aorta or coronary arteries and was potentiated in mesenteric arteries from Zucker obese rats. Our data suggest that diabetes enhances the progression of vascular dysfunction. Increases in indices of oxidative stress precede the development of dysfunction and may serve as a marker of endothelial damage.

Animals↗
PubMed1995

Mesenteric blood pressure profile of conscious, freely moving rats.

1. Blood pressure has been measured in the aorta and at four points in the mesenteric circulation of conscious, freely moving rats under physiological, resting conditions. 2. Using small polythene catheters, blood pressure was measured simultaneously in the aorta and either distally in the superior mesenteric artery (group A), at the base of a mesenteric arterial arcade (vessel diameter ca 100 microns) (group B), at the base of a mesenteric venous arcade (group C) or distally in the superior mesenteric vein (group D). Local blood flow distribution proximal and distal to the measurement point was restored after the cannulations through appropriate ligations. 3. In conscious animals 5-17 h after surgery, systemic mean blood pressure was 121 +/- 2 mmHg. Local pressures at the four locations (as a percentage of systemic pressure) were: 95 +/- 1% in group A, 64 +/- 2% in group B, 13 +/- 1% in group C and 7 +/- 1% in group D. Thus, large arteries dissipated 5% of the total pressure drop, arcade small arteries 31%, the intramural circulation 51%, arcade veins 6% and the remaining veins plus the hepatic circulation 7%. 4. Immediately after surgery, the corresponding pressure drops were 4, 16, 66, 5 and 9%, respectively, thus emphasizing that the pressure profile can be profoundly affected by surgery and anaesthesia. 5. The data indicate that under resting conditions in conscious, freely moving rats, half the mesenteric vascular resistance resides outside the intramural circulation, primarily in the arcade small arteries.

Animals↗
PubMed1975

[The collateral circulation for occlusion of the three unpaired abdominal arteries (author's transl)].

A fifty-two year old patient had only a short period of abdominal angina, despite occlusion of all three unpaired abdominal aortic branches. An extensive collateral system provided the circulation to the abdominal organs: intercostal arteries and adrenal vessels through the inferior phrenic artery for the coeliac trunk; arteries from the left iliac for the inferior mesenteric artery and through Riolan's arc (type II) for the superior mesenteric artery. Lumbar vessels provided a supply to the proximal territory of the superior mesenteric artery. In addition, it was possible to demonstrate connections between several lumbar arteries; several of these were also occluded proximally.

Abdomen↗
PubMed1995

Laparoscopic harvesting of jejunal free flaps.

We studied the safety and efficacy of laparoscopic jejunal free flap harvesting with total intracorporeal small-bowel anastomosis in an animal model. Eight dogs underwent laparoscopic resection of 8 to 15 cm of jejunum with endoscopic GIA anastomoses and jejunal segment harvesting through the periumbilical laparoscopic port. In six animals, the harvested jejunum was implanted subcutaneously and revascularized by anastomosis of the mesenteric artery and vein to the femoral vessels. Both the microvascular and intracorporeal jejunal anastomoses were studied at 10 days. Mean laparoscopic operative time was 2.9 hours, with the last five procedures all completed in fewer than 2 hours. Mean ischemic time was 1.9 hours. The laparoscopically performed small-bowel anastomoses were all successful. All dogs took regular diets within 1 day, with normal bowel function returning by the second day. Both clinically and histologically, the bowel wall and mesenteric vessels of all the segments harvested demonstrated no injury despite their laparoscopic harvest. Five of the free flaps remained fully viable at 10 days. One flap failed after prolapse of the flap resulting from inadequate fixation. Laparoscopic harvesting of the jejunal free flap is safe and efficacious and offers all of the potential advantages of laparoscopic abdominal surgery.

Anastomosis, Surgical↗
PubMed1999

Vascular dilatatory responses to sodium nitroprusside (SNP) and alpha-adrenergic antagonism in female and male normal and diabetic rats.

Diabetes is associated with impaired vascular dilatatory responses that appear to be influenced by sex as well as diabetic state. Therefore, we hypothesized that vascular and sympathetic control function exhibit a greater deterioration following the induction of diabetes in female than in male rats. We conducted a comparative determination of the effect of sodium nitroprusside (SNP, a nitrous oxide donor) and that of an alpha1-adrenergic antagonist, prazosin, on selective vascular flows, mean arterial pressure (MAP), and heart rate (HR), in female and male normal and diabetic rats. Rats were made diabetic using streptozotocin (50 mg/kg, iv) and maintained for 5-6 weeks. Following anesthesia with urethane/alpha-chloralose, the femoral artery and vein were cannulated for recording and sampling. Flow probes were placed on the iliac, renal, and superior mesenteric arteries. SNP (1, 5, 10, and 20 microg/kg) infusions resulted in a dose-dependent decrease in MAP in normal and diabetic rats. The decrease in MAP in normal males was 37% less at the 20 microg/kg concentration of SNP when compared to normal females. The HR was not significantly changed in response to the hypotensive effect of SNP; however, reflex tachycardia was more prominent in diabetic males. The vascular conductance (flow/MAP) was increased by SNP in normal and diabetic rats in a dose-dependent fashion; however, the responsiveness was decreased in the iliac and superior mesenteric and increased in the renal arteries in diabetics when compared to normals. Diabetic males were 42% and 28% less responsive to SNP in the iliac and superior mesenteric arteries, respectively. On the other hand, diabetic females were 1.5-fold more responsive in the renal artery when compared to normals. Prazosin (4 mg/kg) decreased the MAP in normal and diabetic rats to a comparable degree. Prazosin increased the vascular conductance in all three vascular beds in normal and diabetic rats with the greater increase occurring in the iliac (118%) and superior mesenteric (110%) arteries. We concluded that diabetes is associated with an increased response to NO in the renal vessels and a decreased response in the iliac and superior mesenteric vessels in both females and males. alpha-Adrenergic tone was greatest in diabetic female and male rats. This study suggests that decreased vascular flow in diabetes is a result of a combination of decreased sensitivity to NO and increased adrenergic tone.

Adrenergic alpha-Antagonists↗
PubMed1986

Small vessel membrane potential, sympathetic input, and electrogenic pump rate in SHR.

Comparative measurements of transmembrane potential (Em) were made in situ in vascular smooth muscle cells (VSM) of mesenteric small principal arteries and veins with innervation and circulation intact. Vessels were in an externalized, topically suffused jejunal loop in 4- to 5-wk-old (initial hypertension) and 12- to 15-wk-old (established hypertension) anesthetized, spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) normotensive control rats. Comparable in vitro measurements of Em were also made in VSM of isolated intact small mesenteric vessel segments (from the 12- to 15-wk-old animals) maintained at their in situ lengths and suffused with physiological salt solution (PSS). During suffusion in situ with control PSS, VSM of both small veins and arteries in older (but not younger)SHR were less polarized than in WKY. Local chemical sympathetic denervation in situ (with 6-hydroxydopamine) hyperpolarized VSM of both vessel types in older (but not younger) SHR to the same Em levels measured in situ in respective WKY vessels. After local denervation, VSM of small arteries (but not veins) of both SHR and WKY remained less polarized in situ than in vitro, suggesting the presence of one or more circulating factors with a specific depolarizing action on the arterial side in both animal types. In vitro, VSM of both small arteries and veins from WKY but not SHR were depolarized immediately by 10(-3) M ouabain. In contrast, reduction of the PSS suffusate temperature to 16 degrees C caused a significantly greater depolarization in VSM of SHR vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1996

[Intravenous spiral CT angiography for assessment before orthotopic liver transplantation: comparisons between tomography, MIP, 3-dimensional surface imaging and intra-arterial DSA].

UNLABELLED: To analyse the efficacy of intravenous spiral CT angiography (SCTA) for the evaluation before orthotopic liver transplantation (oLT) compared with DSA. METHODS: Spiral CT was performed on 31 potential recipients of a liver graft in order to examine hepatic vessels, coeliac axis, splenic artery and superior mesenteric artery. The arterial vessels were reconstructed in "Maximum Intensity Projection (MIP)" and "Shaded Surface Display (SSD)"-technique. The axial images, MIP and SSD were compared in 25 patients with DSA with regard to the visualisation of the vascular anatomy, detectability of stenosis and vascular diameters. RESULTS: The type of arterial liver supply could be determined via SCTA in all patients. Stenosis of the coeliac axis was seen in ten patients on the DSA, MIP and SSD and in eight patients on the axial images. Occlusion of the hepatic artery was clearly visualised in two patients on the DSA, axial images and MIP and in one patient on the SSD. There was no false positive diagnosis with SCTA. SSD was seen as the best technique to visualise the vessels without overshadowing. There were no significant differences between the diameters measured from the axial images, MIP and SSD images in transversal direction and the DSA images (p > 0.05). CONCLUSION: SCTA is a greatly promising method for the imaging of vessels supplying the liver before oLT, and may convey more diagnostic information than DSA.

Adult↗
PubMed1990

Characterization of vasopressin actions in isolated submucosal arterioles of the intestinal microcirculation.

Submucosal arterioles are the final resistance vessels of the mesenteric circulation; they supply intestinal mucosa and smooth muscle and contribute significantly to total mesenteric resistance. Characterization of receptors present on submucosal arterioles has not been carried out, because these vessels have not been accessible to study by previous methods. We have used a novel optical method for on-line tracking of outside diameter from in vitro preparations of submucosal arterioles in the ileum and colon of guinea pigs, rabbits, and humans to characterize the vasoconstrictor responses to vasopressin as well as other vasopressor agents along the gastrointestinal tract. All ileal submucosal arterioles showed smoothly graded constrictor responses, whereas colonic arterioles from each species exhibited rhythmic vasoconstrictions. Vasopressin constricted guinea pig and human submucosal arterioles (EC50, 1 nM) by activating classical V1 receptors; dissociation equilibrium constants (Kd) for the V1 antagonist d(CH2)5 Tyr (Me) arginine vasopressin were 1-3 nM. This antagonist was 10-50-fold more potent in inhibiting vasopressin constrictions in rabbit submucosal arterioles (Kd = 0.05-0.1 nM). No evidence for the presence of V2 receptors was obtained in any arteriole, and no significant differences in the alpha 1-adrenoceptor-mediated constrictions were observed in these vessels. Results from this study suggest the presence of heterogeneity of V1 receptors in submucosal arterioles; these differences appear to be species dependent. Our results also suggest that intrinsic vasoconstrictor properties of submucosal arterioles differ along the length of the gastrointestinal tract; these differences appear to be species independent.

Animals↗
PubMed1998

Distribution of the perivascular nerve Ca2+ receptor in rat arteries.

We recently showed that perivascular sensory nerves of mesenteric branch arteries express a receptor for extracellular Ca2+ (CaR), and reported data indicating that this CaR mediates relaxation induced by physiologic levels of Ca2+. We have now tested whether the perivascular sensory nerve CaR-linked dilator system is a local phenomenon restricted to the mesentery, or is present in other circulations. Vessels from the mesenteric, renal, coronary, and cerebral circulations were studied. Immunocytochemical analysis was performed using anti-CaR and anti-neural cell adhesion molecule (NCAM) antibodies. Wire myography was used to assess contraction and relaxation. Although perivascular nerves of all arteries stained for CaR protein, there were regional differences. A morphometric method used to estimate CaR positive nerve density revealed the following rank order: mesenteric branch artery > basilar artery = renal interlobar artery > main renal trunk artery > left anterior descending coronary artery. Vessels from the mesentery, renal, coronary, and cerebral circulations showed nerve-dependent relaxation in response to electrical field stimulation (EFS) when precontracted with serotonin in the presence of guanethidine. The degree of Ca2+-induced relaxation of mesenteric, renal, and cerebral arteries positively correlated with the magnitude of EFS-induced relaxation. In contrast, coronary arteries contracted at Ca2+ levels between 1.5 and 3 mmol L(-1), and relaxed to a small degree to 5 mmol L(-1) Ca2+. Thus, a functional perivascular sensory nerve CaR-linked dilator system is present to varying degrees in the mesenteric, renal, and cerebral circulations, but only to a very limited extent in the coronary circulation.

Animals↗