[EXPERIMENTAL AND CLINICAL DATA ON THE MESENTERIC CIRCULATION AND CHRONIC MESENTERIC ARTERITIS].
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Angiography↗
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Co-ordination of pumping in isolated bovine lymphatic vessels.
1. Segments of bovine mesenteric lymphatic of varying diameter taken from different parts of the lymphatic tree were cut to 20 mm in length and set up so that measurements could be made of spontaneous isometric contractions. 2. There was considerable variability in frequency of spontaneous contractions but this was independent of resting tension. There was no significant correlation between lymphatic diameter and inherent frequency of contraction. 3. Isolated segments of bovine mesenteric lymphatic 70-80 mm in length were cannulated and set up in a three-compartment organ bath which allowed independent temperature control in each compartment. Pressure was recorded at inflow and outflow ends and experiments were video recorded. 4. Contractile activity was normally initiated at the end of the lymphatic maintained at the higher temperature and the contractile wave was propagated along the length of the vessel. 5. Propagation could occur either in the direction of valve orientation (orthograde) or retrogradely. The volume of fluid pumped was not significantly affected by the direction of propagation. 6. Perfusion of the central compartment with Krebs solution at 0-2 degrees C disrupted normal propagation and allowed the two parts of the lymphatic to contract at different frequencies although the two parts maintained an approximately 2:1 ratio. 7. Perfusion of the central compartment with 10 mM-heptanol also disrupted normal propagation but the rates on either side of the partition bore no harmonic relationship to one another. 8. These results suggest that relatively short segments of lymph duct have the ability to contract spontaneously and that their inherent frequencies are not determined by their position in the lymphatic tree. The results are consistent with the existence of electrical coupling along the lymphatic's length and they suggest that over distances of at least 80 mm independent pacemakers are capable of mutual entrainment at a frequency representing a compromise between the fastest and slowest components.
Alcohols↗
Superior mesenteric artery bypass for chronic mesenteric ischaemia: a DGH experience.
This article evaluates the results of single vessel bypass surgery for symptomatic chronic mesenteric ischaemia (CMI) in 6 patients undergoing a total of 8 superior mesenteric artery (SMA) bypass operations, all with good post-operative symptom relief. Post-prandial pain and weight loss was present in 5 out of 6 patients. Epigastric bruit was present in only two patients and 4 out of 6 patients had diarrhoea. The patients had varying degrees of peripheral vascular disease, ischaemic heart disease and hypertension. All patients had occlusion of the SMA on angiography and bypassing the occluded segment resulted in disappearance of the symptoms and weight gain. The vascular graft was sutured end to side to the front of the infra-renal aorta and end to side to the SMA, distal to the origin of the middle colic artery. Two patients had recurrence of symptoms due to graft occlusion at 3 and 4 years, respectively; they were successfully treated with repeat SMA bypass. There were no major complications or deaths related to the procedure in this study; one patient developed an incisional hernia requiring elective repair. Thus, early restoration of SMA circulation by bypass grafting in patients with CMI is sufficient to alleviate symptoms and prevent intestinal infarction with its high mortality rate.
Adult↗
[Study of the mesenteric arteries with multislice spiral CT angiography].
The aim of our study was to optimize an high-resolution CT angiography protocol for the evaluation of mesenteric arteries using a multislice spiral CT equipment. A volumetric dataset was acquired during dynamic i.v. injection of non-ionic iodine contrast medium; images were subsequently reconstructed by means of a dedicated off-line workstation, equipped with volume-rendering software. Excellent depiction of the anatomy of mesenteric arteries and collateral vessels was obtained in all the cases. In conclusion, new multislice spiral CT scanners allow an optimal noninvasive evaluation of mesenteric arteries, possible up to now only with catheter angiography.
Aged↗
[Lymph pressure dynamics in somatic and mesenteric lymphatic channels at rest and at the height of digestion].
An original rapidly acting tensoresistive pressure transducer was used to study the lymph pressure in the popliteal and mesenteric lymph nodes and vessels of the dog without liquid injection into the lymph channels. The characteristics of the lymph flow in the drained organs was compared at a relative rest, while for the mesenteric lymph channels at the height of digestion. During digestion the lymph pressure in the vessels and nodes is 2-3 times higher than on an empty stomach, and the waves of tonic activity occur more frequently and energetically. The lymph pressure in the lymph nodes is lower than in the efferent vessels of these nodes.
Animals↗
Verapamil and nifedipine inhibition of contractions induced by potassium and noradrenaline in human mesenteric arteries and veins.
Ring preparations of human mesenteric arteries and veins were contracted by noradrenaline (1.8 x 10(-5)M) or potassium (127mM). Isometric tension was recorded. In the arterial preparations, the maximum response to noradrenaline was 97 +/- 8% (mean +/- S.E.M.) of that to potassium. In the veins, the corresponding figure was 38 +/- 4%. The calcium antagonists verapamil (2.2 x 10(-7)-2.2 x 10(-5)M) and nifedipine (2.9 x 10(-8)-2.9 x 10(-6)M) relaxed both arteries and veins contracted by noradrenaline or potassium, and reduced the responses to these agents when added 15 min. before stimulation. The time course of relaxation of potassium contracted preparations, induced by verapamil and nifedipine, was more rapid and complete than that produced by a calcium-free, high potassium solution. In contrast to verapamil, nifedipine caused a more pronounced inhibition of the potassium than of the noradrenaline evoked contractions in both arteries and veins. After exposure to a calcium-free medium for 30 min., the arterial response to noradrenaline was significantly (P less than 0.05) greater than that to potassium. However, the reverse was found in the veins. In both types of vessel, verapamil (2.2 x 10(-6)M) and nifedipine (2.9--10(-7)M) were equi-effective in reducing the noradrenaline reactivity, not only between mesenteric arteries and veins, but also between, e.g. peripheral and mesenteric vessels. The calcium antagonists nifedipine and verapamil do not have an identical mode of action. However, both agents seem to inhibit influx of extracellular calcium, and might also have an inhibitory effect on the release of intracellular calcium.
Aged↗
Effects of diabetes and uremia on mesenteric vascular reactivity.
BACKGROUND: Diabetes and uremia are comorbid conditions that have significant effects on cardiovascular physiology. These studies were designed to examine the effects of diabetes and uremia on vascular reactivity. METHODS: Sprague-Dawley rats were divided into control (C), diabetic (D), uremic (U), and diabetic/uremic (D + U) groups. Diabetes (D, D + U groups) was induced with an injection of streptozotocin. Uremic (U, D + U groups) was produced by seven-eighths nephrectomy. Serum glucose, blood urea nitrogen, creatinine, creatinine clearance, and protein excretion were measured at baseline and before microvascular studies at 4 or 8 weeks after injection. Vascular reactivity was studied in isolated, pressurized, and superfused segments of mesenteric arterioles (300 microns). Changes in internal vessel diameter were measured in response to phenylephrine (10(-8) to 10(-4) mol/L), acetylcholine (10(-9) to 10(-5) mol/L), and nitroprusside (10(-9) to 10(-2) mol/L). RESULTS: Results at 4 and 8 weeks were similar in all groups. Vasoconstrictor responses to phenylephrine and endothelium-independent vasodilator responses to nitroprusside were not altered in any experimental group. Endothelium-dependent vasodilator responses to acetylcholine were significantly depressed in both diabetic groups (D and D + U, p < 0.01 versus control), and there were no differences between the two diabetic groups. CONCLUSIONS: Streptozotocin-induced diabetes results in impairment of endothelial-dependent (nitric oxide mediated) vasodilator responses in mesenteric resistance vessels, which are unaffected by coexisting uremia. Uremia has little effect on mesenteric vascular reactivity in this model.
Acetylcholine↗
Superior mesenteric vascular anatomy at US in patients with surgically proved malrotation of the midgut.
The purpose of this study was to determine the frequency with which inversion of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) is seen at ultrasound (US) in children with malrotation. Nine patients with malrotation at upper gastrointestinal (UGI) radiographic examination (surgically confirmed) were studied prospectively. Anatomic relationships between the SMA and SMV were evaluated with real-time US in an axial projection, with the transducer placed at the midline of the anterior abdomen. Use of duplex imaging confirmed which vessel was the artery and which was the vein. Vessels were considered to be inverted if the SMV was left of the left lateral margin of the SMA. The SMA and SMV were inverted in six patients (67%) and were normal in three (33%). One patient with normal mesenteric vessels had midgut volvulus; duodenojejunal resection was required. Inversion of the SMA and SMV at US is not sufficiently sensitive to screen patients for malrotation. UGI examination remains the standard modality to diagnose this disorder.
Child↗
[Case report of asymptomatic arteriovenous malformation (AVM) of the pancreas; diagnostic advantage of three-dimensional computed tomography].
A 72-year-old man with diabetes mellitus and hypertension was admitted for further examination and therapy of diabetes. In order to evaluate his pancreas, abdominal computed tomography (CT) was performed, showing a space-occupying lesion (SOL) in the pancreatic uncus. He did not show any symptoms related to the pancreas or gastro intestinal tract. Three-dimensional CT (3D-CT) indicated that the SOL was not a solid tumor but a vessel fistula, fed by the superior mesenteric artery and the gastro duodenal artery, drained by the superior mesenteric vein. Abdominal angiography also showed its peculiar vessel structure, confirming arterio-venous (A-V) malformation in the pancreas. Pancreatic A-V malformation is a rare condition but should not be forgotten in the differential diagnosis of pancreatic SOL. Our case showed the advantages of 3D-CT with its low invasiveness and convenience for the diagnosis of A-V malformation in the pancreas.
Aged↗
Absorption of phenolsulfonphthalein as a model across the mesenteric surface in rats to determine the drug absorption route after intraperitoneal administration.
The purpose of this study was to clarify the absorption characteristics of a drug across the mesenteric surface, which occupies a large area of absorption in the peritoneal cavity, in order to determine the drug absorption route after intraperitoneal administration. Absorption of phenolsulfonphthalein (PSP) as a model after application to the mesenteric surface was investigated in rats by employing a cylindrical diffusion cell attached to the mesentery with or without blood vessels. PSP was absorbed from the rat mesenteric surface, followed by its appearance in the plasma and bile, regardless of blood vessel existence. The absorption ratios of PSP in 6 h were calculated to be 92.1 and 83.6% from the mesenteric surface with and without blood vessels, respectively. We then employed an experimental system in which a polyethylene (PE) cap was stuck on the surface of the other side to exclude the influence of absorption of the drug from the other organ surfaces that penetrated across the mesentery. The PE cap decreased the appearance of PSP in the plasma from the mesenteric surface with blood vessels and eliminated the PSP absorption completely from the mesenteric surface without blood vessels. Accordingly, blood vessels on the mesenteric surface must actually play an important role in drug absorption, but the contribution of the mesenteric surface to drug absorption from the peritoneal cavity is unlikely to be significant because there is a small effective area of blood vessels.
Animals↗
Adenosine mediation of mesenteric blood flow.
The mesenteric circulation is regulated by multiple mechanisms, there is sufficient reason to support the suspicion that local metabolic factors are especially important in the control of intestinal vasculature. Of these, adenosine, a purine nucleoside and mesenteric vasodilator, may be the messenger of the intestinal tissue to signal appropriate responses of the intestinal vessels. The evidence supporting the candidacy of the nucleoside as a local regular of mesenteric circulation may be summarized, as follows: Adenoside is present in the tissue of the gut in measurable quantities. Exogenous adenosine is a powerful dilator of mesenteric resistance vessels. Blockade of adenosine receptors in the mesenteric circulation interferes significantly with three autoregulatory phenomena, i.e., postprandial hyperemia, pressure-flow autoregulation, and reactive hyperemia. The evidence which weakens the role of adenosine as mesenteric vasoregulator includes: Findings in several reports that adenosine depressed intestinal oxygen consumption. The failure of adenosine receptors to inhibit some autoregulatory hyperemias of the gut and the rather limited amount of evidence regarding tissue adenosine release in autoregulatory responses of the gut's vasculature.
Adenosine↗
Borderline resectable pancreatic cancer.
Rigorous criteria to define "borderline resectable" pancreatic cancer are required for appropriate patient accrual into clinical trials that examine the utility of chemotherapy and/or chemoradiation that will be delivered prior to pancreatic resection for exocrine cancer. At our institution, tumor abutment of less than or equal to 180 degrees (< or = 50% of the vessel circumference) of the superior mesenteric artery, short segment abutment or encasement (> or = 50% of the vessel circumference) of the common hepatic artery (typically at the gastroduodenal artery origin), or segmental venous occlusion are used to categorize a pancreatic tumor as borderline resectable. These patients are at a high risk for margin positive resection with initial surgery; therefore, we favor a treatment schema that incorporates preoperative (neoadjuvant) therapy with systemic chemotherapy and chemoradiation. Patients whose tumors show radiographic stability or regression that are often accompanied by an improvement in serum tumor markers are candidates for pancreaticoduodenectomy. A prospective multicenter clinical trial with well-defined eligibility criteria may help decide the best overall treatment strategy for these patients. Vascular resection and reconstruction may be required in patients with borderline resectable tumors, and surgery should be performed at centers with expertise in such complex pancreatic resections.
Journal Article↗
The role of shear forces in ischemia/reperfusion-induced neutrophil rolling and adhesion.
Intravital microscopy was used to examine the role of reduced shear forces on neutrophil-endothelium interactions in single 25-40 microm diameter vessels in the feline postischemic mesenteric microvasculature. Neutrophil rolling, neutrophil adhesion, and microvascular permeability alterations were determined in vessels exposed to ischemia/reperfusion in untreated animals and in cats that received feline plasma directly into the superior mesenteric artery to increase intestinal blood flow and venular shear rates. Ischemia, followed by reperfusion, caused a profound increase in venular shear forces during the initial hyperemic response, which then decreased to below control values by 10 min of reperfusion and to less than 50% of control by 60 min of reperfusion. Associated with the decrease in blood flow was a profound increase in neutrophil rolling and neutrophil adhesion and an increase in microvascular permeability. Also, leukocyte rolling velocity decreased dramatically to 10-20% of control values during the first 10 min of reperfusion. Infusion of autologous plasma into the intestinal vasculature to maintain the shear forces at control levels during reperfusion did not affect the flux of rolling neutrophils. The rolling velocity of the neutrophils was not increased despite dramatically improved shear rates. Improved shear rates did reduce the number of adherent cells, resulting in less vascular dysfunction. The reduction in shear forces through inflamed microvessels does not contribute to the increased leukocyte rolling flux but is an essential, permissive component for neutrophil adhesion and subsequent vascular dysfunction in postischemic microvasculature.
Animals↗
Spike generating smooth muscle cells in mesenteric artery of rats.
Membrane electrical properties of smooth muscle cells at different loci in the vessel wall of rat small mesenteric arteries were studied using glass microelectrodes. Isometric force was measured simultaneously. Penetrations of smooth muscle cells on the adventitial side (outer cells) showed an average resting potential, -43.1 +/- 0.8 mV (n = 24). In outer cells, numerous depolarizing junctional potentials and, to a lesser degree, hyperpolarizing junctional potentials were observed. When current was injected, electrotonic potentials were recorded. Input resistance was 2.2 +/- 0.1 x 10(9) omega (n = 15), suggesting that the low resistance pathways commonly observed in smooth muscle tissue are absent among these cells. Transmural electrical stimulation of nerves elicited spikes and summation of junctional potentials, accompanied by force. TTX virtually abolished these effects of the transmural stimulation. In contrast, cells near the intima (inner cells) had an average resting potential of -65.8 +/- 0.9 mV (n = 37). No spontaneous electrical activity was observed; nor could electrotonic potentials be recorded. Thus, the smooth muscle cells from the outer layer of rat small resistance arteries differ from the inner cells in their lower membrane potentials, generation of spikes, higher input resistance and innervation. Results also suggest that the influence of nerves may be to facilitate opening of voltage-gated Ca2+ channels in innervated cells.
Action Potentials↗
In vivo integrated flow image cytometry and lymph/blood vessels dynamic microscopy.
The high spatial resolution (approximately 350 nm) transmission digital microscopy (TDM) was developed for real time in vivo imaging of microlymphatics of rat mesentery at a single cell level without any contrast agent. The main mesenteric microstructures (lymph-vessel diameter, valve geometry, cells, etc.) and their dynamics (wall motion, valve function, cell velocity, etc.) were monitored with TDM. Depending on structure size, different magnifications were used to image relatively large whole lymphangion (x4 to x10) as well as to image single cells (x40 to x100) in lymph and blood flow including estimation of their shape, size, and aggregation state. Various potential applications of the TDM for in vivo studies are discussed, including visualization of circulating cells in lymph and blood flows, studying the kinetics of platelets, leukocyte rolling, as well as imaging absorbing nonfluorescent mesentery structures and leukocytes with a high optical resolution.
Animals↗
Endothelial cilia in rat mesenteric arteries and intramyocardial capillaries.
We report for the first time the presence of endothelial cilia in rat blood vessels. They are seen in the mesenteric arteries of hypertensive rats and the intramyocardial capillaries of aged rats. The cilia are solitary and have the shape of the "9 + 0" axonemal structure. The processes of the basal foot and the transitional fiber are accompanied by basal bodies. The function of the solitary cilia is obscure.
Animals↗
Ultrastructural changes in blood vessels of perinephritic hypertensive dogs.
Mesenteric arteries and saphenous veins of control and perinephritic hypertensive dogs were studied with light and electron microscopy. 2 weeks after surgery there are ultrastructural changes, both in arteries and veins which are thought to be of hydroelectrolytic origin. These alterations are more marked 7 weeks after surgery and disappear thereafter. There are signs of increased protein synthesis activity in the smooth muscle of the mesenteric arteries, but not of the saphenous veins obtained 7 and 14 weeks after surgery, leading to a progressive hypertrophy of the muscular cells. The connective tissue augmented proportionally. Degeneration of adrenergic nerves in the arteries, accompanied by a parallel decrease in their noradrenaline content, constituted an unexpected finding clearly deserving further study.
Animals↗
Increased capillary hydraulic conductivity induced by atrial natriuretic peptide.
The small molecular weight peptide, atrial natriuretic peptide (ANP), produces marked sodium and water excretion. The peptide, extracted from several species of vertebrate heart, also has been shown to increase glomerular filtration and reduce plasma volume. Several mechanisms have been proposed to account for the action of the peptide but remain undefined. In the present report, the ANP-induced alterations in transcapillary water movement were directly assessed. The modified Landis technique was used to measure single capillary hydraulic conductivity (Lp) of vessels from the frog mesenteric circulation. In 6 individual microvessels, Lp was measured under control conditions and again during perfusion with 10 X 10(-6) M ANP. The Lp increased in each vessel by a mean of 3.79-fold (+/- 2.09 SD). In 4 of these vessels, an additional measurement of Lp was repeated under control conditions; the capillary filtration coefficient returned to control levels. It was concluded that ANP directly and reversibly elevates capillary hydraulic conductivity; this response is independent of changes in capillary hydrostatic pressure or surface area.
Animals↗