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PubMed2004

Mechanisms involved in the vasodilator effect of the flavanol floranol in rat small mesenteric arteries.

The mechanism underlying the vasodilator effect of the flavonoid floranol was studied in rat small mesenteric arteries. Floranol produced a concentration-dependent vasorelaxant effect in endothelium-containing and endothelium-denuded vessels pre-contracted with phenylephrine, which was more potent in endothelium-intact vessels. In endothelium-intact mesenteric arteries, l-NAME but not indomethacin produced a shift to the right in the vasorelaxant effect of floranol. In endothelium-denuded vessels TEA and BaCl2 did not change the floranol-induced vasorelaxation. When endothelium-denuded vessels were pre-contracted with 50 mM KCl, floranol induced a vasorelaxant effect comparable with phenylephrine pre-contracted vessels. We conclude that floranol is a new vasodilator compound in rat small mesenteric arteries. Part of this effect is dependent on endothelial nitric oxide (NO) and part is dependent on the inhibition of voltage-dependent calcium channels in the smooth muscle cells.

Animals↗
PubMed1996

Extraperitoneal laparoscopic para-aortic lymph node dissection.

Extraperitoneal cervical cancer "staging" is considered superior to a transperitoneal approach. We developed an entirely extraperitoneal laparoscopic technique for para-aortic lymph node dissection in a pig model, followed by human subject application. Using latex balloon dissection technology, the technique is as follows. A retroperitoneal space is created via a 15-mm left flank incision. The collapsed balloon trochar is inserted and the balloon is inflated under direct visualization. Subsequently, a CO2 pneumoretroperitoneum is established with 12-15 mm Hg and dissection is carried out using a total of three to four left flank port sites. For initial technique development and improvement, four pigs were used. Excellent bilateral retroperitoneal exposure was achieved. A complete dissection was performed from the renal to the iliac vessels. Subsequently, a bilateral sampling procedure from the level of the inferior mesenteric artery to the liac vessels was performed in four human subjects. A mean of 5 nodes (range 1-9) was removed with an EBL of <50 cc. Operative times were 120-140 min. There were no intra- or postoperative complications. This initial experience demonstrates that laparoscopic extraperitoneal para-aortic access and node sampling is feasible. Further study is ongoing to determine the extent of dissection possible using this approach. However, since this approach mimics the extraperitoneal laparotomy technique, it may have all the advantages of adhesion avoidance combined with an outpatient procedure.

Animals↗
PubMed2001

Multislice spiral computed tomography angiography of mesenteric arteries.

The introduction of multislice technology has improved and expanded the clinical applications of computed tomography angiography (CTA), and it is now possible to detect subtle vascular abnormalities. We optimised a high resolution CTA protocol to study the anatomy of mesenteric arteries with a multislice spiral CT scanner. We showed that multislice CTA produces images of high quality, with excellent anatomical visualisation of the main mesenteric trunks, and small collateral vessels. CTA may facilitate the diagnosis of vascular diseases, such as chronic mesenteric ischaemia, as well as acute disorders such as gastrointestinal bleeding.

Adult↗
PubMed1996

Alpha-adrenergic, neurokinin and muscarinic receptors in rat mesenteric artery; an mRNA study during postnatal development.

Developmental studies show that the innervation of autonomic targets is accompanied by increases in the density of receptors, maturation of receptor-signalling pathways and changes in receptor subtype. The innervation of the rat mesenteric artery occurs over the first 3 postnatal weeks. In this study, we investigated whether alterations in receptor gene expression may underlie physiological changes recorded during development and maturity in this vessel. Total RNA, from mesenteric arteries of rats at birth and postnatal days 7, 14, 28, 240 and 360, was reverse transcribed and amplified using primers specific for the alpha 1 (A, B, D)- and alpha 2 (A, B, C)-adrenergic, neurokinin (NK1-NK3) and muscarinic (m1-m5) receptors. Results showed that all receptor genes expressed at 28 days, except the alpha 1D-adrenergic receptor, were already expressed at birth. Some receptor subtypes showed no change in their relative expression, always being either strongly (alpha 1A, alpha 2B, NK3) or weakly (alpha 2A, alpha 2C, NK1) expressed. Relative to the expression of these receptors, others showed a developmental increase in expression up to 14 days postnatal (alpha 1B, alpha 1D, m2, m3, m5) but no further change with maturity. These latter changes coincide with the development of sympathetic and sensory nerve plexuses in the mesenteric artery, but do not correlate with the physiological changes seen during development and ageing.

Animals↗
PubMed1998

Effects of environmental stress on the architecture and permeability of the rat mesenteric microvasculature.

OBJECTIVE: This study was performed to determine the effects of environmental stress on the leakage to albumin and architecture of microvessels in the rat mesentery. METHODS: One group of rats (Group A, n = 6) were examined immediately upon arrival at the animal care facility. Groups B (n = 24) and C (n = 32) were housed in rooms with high and low personnel activity, respectively, for up to 7 weeks. Group D (n = 18) was housed in the high activity room for 2, 3, or 4 weeks followed by the low activity room. RESULTS: Rats in the low activity room for 3-4 weeks showed robust microvascular networks within 25% to 50% of the mesenteric windows (each window consisting of the tissue extending between two adjacent feeding arterioles in the mesentery), whereas rats in Group B only showed fragile vessels at the edges of the mesenteric windows within fat deposits. Groups A and C demonstrated little mesenteric fat and few fragile vessels, in contrast to group B. Group D showed increased mesenteric networks and decreased mesenteric fat as recovery progressed. The microvascular networks of 6 rats, randomly selected from Group C, showed few venular leaks following perfusion with fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA). Such leaks were abundant in the mesenteric microvasculature of 3 rats randomly selected from Group B. CONCLUSIONS: This study demonstrates that environmentally induced stress alters the architecture and leakage to albumin of the rat mesenteric microvasculature, and emphasizes the importance of closely monitoring the environment of experimental animals.

Animals↗
PubMed2003

Mesenteric thrombosis causing short bowel syndrome in nephrotic syndrome.

Nephrotic patients are at risk of developing venous and arterial thrombotic complications. Pulmonary embolism due to affected deep leg veins is by far the most common event. Renal or cerebral vein thromboses have been described. Thrombosis of arterial vessels is less frequent. Mesenteric infarction is a rare but severe complication in patients with nephrotic syndrome (NS). We report a 7-year-old boy with a steroid-dependent (SD) NS and a homozygous mutation of methylenetetrahydrofolate reductase, increasing the risk of thromboembolic events. He developed a thrombosis of his superior mesenteric artery during his ninth relapse, which was responsible for a necrosis of 240 cm of his small bowel, necessitating resection of necrotic parts and double external ostomy diversion. Remission was achieved with pulse prednisolone therapy. Corticoids were reduced over 4 months progressively. Oral cyclosporin A (CyA) was initiated for long-term treatment. Due to a short bowel syndrome with severe malabsorption, even oral administration of 22.5 mg/kg per day CyA did not lead to sufficient plasma levels. Intravenous cyclophosphamide pulse therapy over 6 months led to a complete remission. No relapse occurred over a period of more than 5 months after the last cyclophosphamide pulse. Anticoagulation and screening for increased susceptibility for thrombotic events are necessary in every nephrotic patient. Intravenous cyclophosphamide pulse therapy is a useful alternative in SDNS with impaired intestinal absorption of applied immunosuppressive drugs.

Child, Preschool↗
PubMed1980

[Effect of phenoxybenzamine on mesenteric blood flow in irradiated rats].

Reactivity of the superior mesenteric artery has been studied in rat Wistar by infusion of biogenic amines (noradrénaline, dopamine, serotonin, acetylcholine and histamine) in presence of phenoxybenzamine. A decrease in reactivity of the post-synaptic alpha receptor located on the mesenteric vascular smooth muscle cell was seen three days after irradiation by 2 Kr.

Animals↗
PubMed1987

Structural alterations of blood vessels in hypertensive rats.

Vascular changes in the mesenteric arteries were examined in three animals models for human essential hypertension. These models are: spontaneously hypertensive rats, which develop hypertension with age; Dahl model of genetic, salt-dependent hypertensive rats; and deoxycorticosterone-salt hypertensive rats. Morphometric measurements of the arterial wall components (e.g., endothelium, media) were carried out in the elastic arteries, muscular arteries, and arteriolar vessels from the mesenteric bed. The observed changes were correlated with the stages of hypertension development and the effect of antihypertension therapy, including sympathectomy. Specific emphasis was made to determine whether the changes observed were primary in nature, and related to the causes of hypertension, or they were secondary adaptive changes. A comparison of the three models showed that common changes in the intima, media, and adventitia were present in the three models. Alterations in the endothelium (e.g., enlargement of subendothelial space, necrotic changes), adventitia (collagen increase), and hypertrophy of the smooth muscle cells are secondary adaptive changes, because these changes occur subsequent to the development of hypertension, and antihypertensive therapy also prevent these changes from taking place. In contrast, hyperplasia of the smooth muscle cells is a primary change, because it occurs prior to the onset of hypertension. Functionally, alteration in the media is probably the most important change, because it can cause hyperreactivity of the arteries in response to stimulation. Damage to the endothelial cells may play a role in the maintenance of hypertension during the later phase. Alteration in adventitia is a passive change, which does not appear to have a major role in hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Evaluation of aortography in assessing the resectability of retroperitoneal neuroblastoma in children.

To assess the resectability of retroperitoneal neuroblastoma and determine the timing of a "second-look" resection of primary tumor on the basis of aortographic findings, 32 abdominal aortographies performed on 26 patients with retroperitoneal neuroblastoma (22 adrenal, 4 paraspinal) were examined retrospectively. Angiographic findings of both displacement of aorta and narrowing of aorta indicate the difficulty of complete removal of the neuroblastoma. These findings were particularly useful in determining the resectability of retroperitoneal neuroblastoma. On the other hand, the absence of angiographic findings of both displacement of main vessels (celiac axis, origin of superior mesenteric artery, or renal arteries) and stretching of main vessels indicate the feasibility of complete removal of retroperitoneal neuroblastoma. On the basis of angiographic findings, the decision to resect the retroperitoneal neuroblastoma could be made in 6 patients, who underwent the "second-look" operation.

Adolescent↗
PubMed1981

[Is there an intestinal lymphatic trunk in man?].

As the analysis of the literature demonstrates, in spite of a rather wide use of the term "tr. intestinalis" and its inclusion into the PNA, it is still not clear what should be understood under this term concerning the human being. It has been stated, by means of coloured mass injections into the efferent lymphatic vessels of the hepatic, celiac and superior mesenteric lymph nodes, that there is no common efferent lymphatic trunk as a result of fusion of these vessels mentioned above. The efferent lymphatic vessels of the hepatic and celiac lymph nodes terminate in the lumbar lymph nodes; 92.1% of the efferent lymphatic vessels of the superior mesenteric lymph nodes also terminate in the lumbar lymph nodes and only 7.9% of these vessels terminate in the thoracic duct or in one of its roots. Thus, there is no classical lymphatic intestinal trunk (middle root of the thoracic duct) collecting lymph from all abdominal organs and discharging into the thoracic duct.

Adolescent↗
PubMed1982

Pharmacological characterization of the alpha adrenoceptors of the dog basilar artery.

The effects of alpha adrenoceptor agonists and antagonists on the postsynaptic alpha receptors were examined in the dog basilar, mesenteric and renal arteries and the type of alpha adrenoceptors present was characterized. In the basilar artery, noradrenaline, clonidine and phenylephrine produced almost the same maximal contraction, the pD2 values being 6.51 +/- 0.11, 5.49 +/- 0.16 and 5.65 +/- 0.13, respectively. Yohimbine (1-3 x 10(-8) M) inhibited the contractile responses to noradrenaline and clonidine competitively and the response to phenylephrine noncompetitively. Corynanthine (10(-6) M) had no effect on such contractile responses. In the mesenteric and renal arteries, the maximal responses to noradrenaline and phenylephrine were markedly greater than those to clonidine. Yohimbine (10(-7) - 10(-5) M) and corynanthine (10(-7) - 10(-5) M) both antagonized noradrenaline competitively in these vessels. In the basilar, mesenteric and renal arteries preloaded with 3H-noradrenaline, 3H-efflux induced by electrical transmural stimulation was attenuated by clonidine (10(-10) - 10(-7) M), while phenylephrine (10(-10) - 10(-8) M) was without effect. Yohimbine at considerably lower concentrations than corynanthine increased the 3H-efflux elicited by electrical stimulation. These results indicate that presynaptic and postsynaptic alpha receptors of the dog basilar artery are largely alpha 2 in contrast to those of peripheral arteries.

Adrenergic alpha-Agonists↗
PubMed1989

Response of the mesenteric circulation to serotonin in normal and atherosclerotic monkeys: implications for the pathogenesis of non-occlusive intestinal ischaemia.

We tested the hypothesis that atherosclerosis potentiates vasoconstrictor responses in the mesenteric circulation to stimulation of serotonergic and alpha-adrenergic receptors. In normal monkeys, infusion of serotonin had little effect on blood flow to the stomach, duodenum, and colon. In contrast, in atherosclerotic monkeys, serotonin produced a modest decrease in blood flow to the stomach and duodenum, and virtually abolished blood flow to the colon. Vasoconstrictor responses to phenylephrine in the stomach and duodenum were not altered by atherosclerosis, but responses were potentiated in the colon of atherosclerotic monkeys. In summary, atherosclerosis greatly potentiates vasoconstrictor responses to serotonin in the mesenteric circulation, particularly in vessels to the colon. We speculate that release of serotonin during adherence and aggregation of platelets at atherosclerotic lesions, coupled with augmented vasoconstrictor responses to serotonin, may play a role in the pathogenesis of non-occlusive mesenteric ischaemia.

Animals↗
PubMed1990

Effects of cyclic AMP-affecting agents on contractile reactivity of isolated mesenteric and renal resistance arteries of the rat.

1. Effects of adenosine 3':5'-cyclic monophosphate (cyclic AMP)-affecting agents were compared in mesenteric and renal resistance arteries that had been isolated from 20 week old Wistar-Kyoto rats, chemically sympathectomized, stretched to their optimal diameter for mechanical performance and made to contract in response to 30 mM potassium. 2. In mesenteric resistance arteries, isoprenaline, dopamine, NaF, forskolin, isobutyl-methylxanthine, milrinone and dibutyryl-cyclic AMP induced relaxation. Clonidine induced further increases in tension that could be reduced by pertussis toxin and prazosin but not by yohimbine. Clonidine also reduced relaxant responses to isoprenaline. 3. In renal resistance arteries, isoprenaline and dopamine failed to induce relaxation. Compared to mesenteric resistance arteries, renal vessels were less sensitive to the relaxant effect of NaF, forskolin and isobutyl-methylxanthine. Relaxant responses to dibutyryl-cyclic AMP did not differ between the two resistance arteries. 4. Indirect evidence thus suggests that in mesenteric resistance arteries, adenylate cyclase is susceptible to pharmacological activation and inhibition and is functionally coupled to relaxation. The refractory nature of renal resistance arteries to the relaxant effects of isoprenaline and dopamine could be due primarily to absence of appropriate receptors and to a relatively low activity of adenylate cyclase.

1-Methyl-3-isobutylxanthine↗
PubMed2003

Impact of renal transplantation on small vessel reactivity.

BACKGROUND: The function of large arteries is altered after renal transplantation. Whether transplantation also induces agonist-dependent functional changes in small arterial renal and extrarenal vessels has not yet been studied. METHODS: Chronic rejection was induced by grafting Lewis rats with kidneys from Fischer rats (FL). Rats that underwent transplantation were bilaterally nephrectomized. Rats that underwent syngeneic transplantation, uninephrectomized rats, uninephrectomized rats with denervated kidneys or with kidneys made ischemic, and native rats served as controls. All animals were treated with cyclosporine for 10 days. Eighteen weeks after surgery, the reactivity of small arteries (220-270 microm) was tested by myography. RESULTS: Weight gain, glomerular filtration rate, and arterial pressure were similar in all groups, whereas proteinuria was elevated in FL. Only kidneys from FL showed glomerular lesions, tubular atrophy, and vasculopathy. Responsiveness of coronary, mesenteric, and femoral resistance vessels to both constrictor and dilator agonists was similar in transplanted and nontransplanted animals. Resistance vessels obtained from both allogeneically and syngeneically transplanted kidneys were more sensitive to norepinephrine, phenylephrine, angiotensin II, and vasopressin than renal vessels from weight-matched controls. Vasodilation in response to acetylcholine and sodium nitroprusside was mitigated in transplanted versus nontransplanted kidneys. CONCLUSIONS: In rat renal transplantation, renal resistance vessel responsiveness to constrictor or dilator stimuli is altered. Extrarenal small vessel function is not affected. The changes in function of renal resistance vessels are not explained by reduction of nephron mass, denervation, ischemia, or chronic rejection.

Angiotensin II↗
PubMed1999

Risk factors and outcomes following revascularization for chronic mesenteric ischemia.

Revascularization for chronic mesenteric ischemia is an infrequent vascular procedure whose objective long-term patency results have been described in relatively few patients. We reviewed our experience with such procedures and report on the objective and symptomatic long-term results. We retrospectively reviewed a consecutive series of 42 patients who underwent mesenteric arterial reconstruction of 66 vessels during an 11-year period from 1986 to 1997. All patients were treated for symptomatic chronic mesenteric ischemia. The results support the clinical efficacy and durability of visceral artery bypass procedures for patients with symptomatic chronic mesenteric ischemia. Patency rates for females were better than for males independent of graft type.

Angioplasty↗
PubMed1983

Ultrastructural changes in mesenteric arteries from spontaneously hypertensive rats. A morphometric study.

Morphometric measurements at the electron microscope level were carried out on three categories of mesenteric arteries representing elastic (superior mesenteric), muscular and arteriolar vessels, from 10- to 12-week-old spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto normotensive rats (WKY). Changes were observed only in muscular and arteriolar vessels of SHR, mainly as thickening of the vessel wall due to hypertrophy of the media. In muscular arteries, hypertrophy of the endothelial cells, widening of the subendothelial space, increased volume of the internal elastic lamina (IEL), and both hyperplasia and hypertrophy of the smooth muscle cells (SMC) in the media contributed to the wall thickening. In arteriolar vessels, increase in the subendothelial space and IEL, and hyperplasia of the SMC in the media were involved in the increased thickness of the vessel wall. There was no difference in the collagen content in all vessels, but elastin was increased in the muscular and arteriolar vessels of SHR. Nerve density was also increased in arteriolar vessels of SHR. These changes, especially the increase of SMC in muscular and arteriolar vessels, may be related to the elevated blood pressure in SHR.

Animals↗