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PubMed2001

Signaling mechanisms for the selective vasoconstrictor effect of norbormide on the rat small arteries.

Norbormide (NRB) is a selective vasoconstrictor agent of the rat small vessels. The mechanisms underlying the selective vasoconstrictor effect of NRB are unknown. To investigate whether phospholipase C (PLC) signaling pathway plays a role in NRB-induced vasoconstriction, we performed experiments in NRB-contracted tissues, namely, rat caudal arteries (RCA) and smooth muscle cells derived from rat mesenteric arteries (MVSMCs). An NRB-insensitive vessel, namely rat aorta (RA), served as a control tissue. In RCA and RA we measured either isometric tension or formation of inositol phosphates (IPs), the latter taken as an index of PLC activation. In MVSMCs, we measured intracellular free calcium concentration ([Ca2+]cyt). In the presence of external Ca2+, NRB (2-50 microM) stimulated IPs formation in RCA but not in RA, and increased [Ca2+]cyt in MVSMCs. In the absence of external Ca2+, NRB (50 microM) increased IPs formation in RCA but was unable to increase [Ca2+]cyt in MVSMCs. In RCA, in the presence of external Ca2+, NRB-induced contraction was inhibited by calphostin C (0.2-1 microM), an inhibitor of protein kinase C (PKC), and by SK&F 96365 (30 microM), an inhibitor of the store-operated calcium channels, but was poorly affected by verapamil, an L-type calcium channel blocker. However, verapamil was much more effective when external Ca2+ was substituted by Sr2+. These results suggest that NRB elicits its tissue and species-selective vasoconstrictor effect by stimulating PLC-PKC pathway and increasing Ca2+ influx through both verapamil-sensitive and -insensitive calcium channels. Ca2+ release from sarcoplasmic reticulum seems not involved in NRB vasoconstriction.

Animals↗
PubMed1994

Intrinsic pumping of mesenteric lymphatics is increased after hemorrhage in awake sheep.

Lymphatic vessels have the ability to contract and transport liquid and protein from tissue spaces to the intravascular space. The purpose of this investigation was to test whether this lymph pump is stimulated following a fixed volume hemorrhage in awake sheep. To quantitate lymphatic pumping in vivo, a mesenteric lymphatic was isolated from all lymph input and provided with Krebs solution at a fixed transmural pressure. A branch of the mesenteric duct was cannulated to provide a measure of lymph flow rate. Each animal was either bled 25% of blood volume over 5 min or was observed. Systemic arterial blood pressure declined in all bled sheep (P < 0.05). Hemorrhage had no effect on lymph flow from mesenteric ducts. However, hemorrhage significantly enhanced lymphatic pumping, approximately 200% of control values 3 hr after hemorrhage (P < 0.01). Increased lymphatic pumping after hemorrhage may play an important role in blood volume and protein restitution.

Animals↗
PubMed1995

Flow-induced dilation in newborn intestine.

The goal of these experiments was to determine the presence and mechanistic basis of flow-induced dilation in mesenteric artery from 3-d-old swine. In the first experiment, in vitro gut loops were perfused from a blood-filled reservoir under controlled-flow conditions, and flow was progressively increased from approximately 40% to approximately 170% in six increments by manipulation of pump speed. Under control conditions, vascular resistance significantly decreased after each step increase in flow rate. NG-Monomethyl-L-arginine (LNMMA; 10(-4) M), an arginine analog that blocks nitric oxide production, eliminated this flow-induced dilation, but only for the step increases in flow at rates above the baseline flow rate. For step increases below the baseline rate, LNMMA caused a simple parallel shift of the resistance-flow rate curve upward. Phenylephrine (10(-6) M), an alpha 1-agonist which has no effect on nitric oxide production or half-life, did not eliminate flow-induced dilation, but instead caused a simple parallel shift of the resistance-flow rate curve upward across the entire range of flows studied. In the second experiment, a 3-cm segment of mesenteric artery was perfused with Krebs buffer at two flow rates: 10 and 25 mL/min. The effluent from the mesenteric artery segment was suffused onto a deendothelialized, phenylephrine-precontracted ring of swine carotid artery; relaxation of this bioassay vessel served as an index of release of relaxing factors from the mesenteric artery segment. Under control conditions, increase in the mesenteric artery flow rate caused a 60% relaxation of the bioassay vessel. This effect was eliminated by the addition of LNMMA to the buffer (10(-4) M), but not by the addition of indomethacin (10(-5) M). Flow-induced dilation occurs in the mesenteric artery of 3-d-old swine. This vascular phenomenon appears to be mediated by nitric oxide, but only at flows above the baseline flow rate. The mechanism(s) responsible for this phenomenon at lower flow rates is not clear.

Animals↗
PubMed2005

[A modified arterial sleeve anastomosis in rat renal transplantation].

OBJECTIVE: To improve arterial anastomosis method for rat renal transplantation. METHODS: Renal transplantations were performed on 72 wistar rats. The donor superior mesenteric artery was end-to-end anastomosed to the recipient left renal artery by using of sleeve anastomosis technique. The external diameters of the vessels anastomosed were 0.60 +/- 0.05 mm (left renal artery) or 0.80 +/- 0.07 mm (superior mesenteric artery). The procedure consisted of a guiding suture and two fixing sutures. The guiding suture was used to "telescope" the recipient left renal artery into the donor superior mesenteric artery about 2 millimetre. Two fixing sutures were applied 180 degrees apart from each other and tied. Three sutures passed through all layers of the donor superior mesenteric artery and constricted the vessel lumen, but only penetrated the adventitia of the recipient left renal artery. RESULTS: The time for arterial anastomoses was approximately 6 to 8 minutes. The renal grafts perfused very well after the recipient left renal artery clamp was removed. Complications included anastomotic hemorrhage (1 case) and thrombosis (1 case). Histologic examination of 34 grafts at different postoperative time ranging from 6 to 30 days revealed that renal artery was fully patent, with no evidence of ischemic injury. CONCLUSION: The modified arterial sleeve anastomosis technique is simple and feasible regardless of experimental condition and can be easily performed.

Anastomosis, Surgical↗
PubMed1991

Portal-systemic encephalopathy: presence of basal ganglia lesions with high signal intensity on MR images.

Sixteen patients with cirrhosis of the liver underwent cranial magnetic resonance (MR) imaging and transarterial portography to evaluate the relationship between basal ganglia lesions and portal-systemic collateral vessels. No neuropsychiatric disturbance was observed in any of the patients at the time of the MR examination, but four patients with portal-systemic encephalopathy were included in the study. Basal ganglia lesions, characterized by increased signal intensity on T1-weighted MR images, were observed in nine of the 16 patients, including the four with portal-systemic encephalopathy. These nine patients had large portal-systemic collateral vessels that were more than 10 mm in diameter. These collateral vessels were receiving blood from the superior mesenteric vein (SMV) in all nine patients. The lesions involved the globus pallidus and portions of internal capsules in a bilateral and symmetric fashion and did not exhibit mass effect. The authors conclude that there may be a significant relationship between high-intensity basal ganglia lesions and large portal-systemic collateral vessels receiving blood from the SMV.

Aged↗
PubMed1981

Hemodynamic effects of rapid injection into the canine superior mesenteric artery.

We explored the hemodynamic effects of rapid injection of 0.9% saline and arterial blood into the canine superior mesenteric artery in anesthetized animals. Mesenteric artery blood flow and pressure were measured in the vessel distal to the site of injection. Injection rates were at or below the rate of blood flow in the mesenteric artery. Rapid injection of saline caused increases in blood flow and decreases in pressure in the mesenteric artery, with responses to saline occurring during or shortly after the period of injection. Injection of arterialized blood into the artery prompted changes resembling those with saline. Injection of blood for up to 16 sec at a rate which was equal to the resting blood flow in the vessel increased both flow and pressure during the period of injection. Blood flow continued at an elevated level for many seconds after cessation of injection. During this time, pressure in the artery fell to a level below the control value. Calculated mesenteric vascular resistance exhibited a decrease during and following injection. Our findings suggest that the hemodynamic response of the superior mesenteric artery to a pulsation of blood or saline is vasodilation.

Animals↗
PubMed1982

Effect of furosemide on canine inferior mesenteric blood flow.

The administration of diuretics to patients receiving cardiac glycosides has been reported to be a contributing factor in the incidence of nonocclusive mesenteric infarction. Presumably, the loss of fluid induced by the diuretics results in a decrease in blood flow to the intestines. This, combined with the vasoconstrictor action of the glycosides, can result in too great a decrease in blood flow and hence the development of an infarct. The ability of diuretics to alter intestinal circulation is supported by animal studies which have shown that blood flow in the superior mesenteric artery is decreased after the administration of furosemide. Since intestinal blood flow is also, in part, supplied by the inferior mesenteric artery, it was of interest to determine the effect of the administration of furosemide on blood flow in this vessel. Following intravenous administration of furosemide (2 mg/kg), inferior mesenteric flow was found to be decreased significantly at 10 minutes and it continued to decline until approximately 40 minutes after administration of the diuretic. Blood pressure was elevated slightly (less than 10 mm Hg) for the first 30 minutes after the administration of furosemide. It would seem likely that the reduction in inferior mesenteric blood flow following administration of furosemide is probably caused by the same factors which mediate the furosemide-induced decrease in superior mesenteric blood flow.

Animals↗
PubMed1988

Age-related changes of noradrenergic innervation of rat splanchnic blood vessels: a histofluorescence and neurochemical study.

The influence of ageing on the noradrenergic innervation of superior mesenteric artery and vein, renal artery and vein, and portal vein was studied in male Wistar rats by means of catecholamine histofluorescence, image analysis techniques and high pressure chromatography with electrochemical detection. Old age was accompanied by a marked increase in the density of noradrenergic innervation and an increase of noradrenaline levels in superior mesenteric artery, renal artery, and portal vein. In contrast, no significant age-related changes were observed in the density of noradrenergic innervation or in noradrenaline levels in superior mesenteric and renal vein. The present data indicate that, at least in superior mesenteric and renal artery and portal vein, senescence is not accompanied by loss or by lack of change in the noradrenergic innervation as commonly believed to be the case in many vascular trees. On the basis of our findings it cannot be excluded that increased plasma catecholamine levels observed in senescence derive, in part, from perivascular sympathetic endings.

Adrenergic Fibers↗
PubMed1996

Effect of acidosis on contraction, intracellular pH and calcium in the rabbit mesenteric small artery.

The purpose of the present study was to determine the effect of various types of acidosis on vessel diameter, intracellular pH (pHi), and calcium concentration ([Ca2+]i) in a cannulated preparation of the mesenteric arteriole of the rabbit. The effect of acidosis on vessel contraction was also studied in the wire-mounted preparation. In the cannulated preparation, pre-contracted by noradrenaline, hypercapnia caused vasoconstriction and increases in [Ca2+]i. In the wire-mounted preparation pre-contracted by either noradrenaline or high KCl, hypercapnia caused a transient vasoconstriction. In contrast, in the cannulated preparation pre-contracted by high KCl, hypercapnia caused a transient vasorelaxation and decreases in [Ca2+]i. Intracellular acidosis, induced by a NH4Cl prepulse, caused vasoconstriction and increases in [Ca2+]i even in the cannulated preparation pre-contracted by high KCl. The decrease in pHi during hypercapnia was similar to that observed after NH4Cl withdrawal. These data suggest that: (1) the effect of acidosis on vascular tone and [Ca2+]i is different depending upon the type of preparation and the mode of pre-activation, and (2) [Ca2+]i may, at least partly, regulate vascular contraction and relaxation during acidosis.

Acidosis↗
PubMed1997

[Chronic mesenteric ischemia--surgical therapy in 3 level occlusion].

A 57-year-old patient with general arteriosclerosis and end-stage renal failure was found to be suffering from occlusion of the mesenteric arteries. The symptoms were rapidly progressive. The aortogram showed that nutrition of the whole intestine took place via a collateral vessel that originated at both internal iliac arteries. Revascularization of the superior mesenteric artery with interposition of Gore-Tex prosthesis and transposition to the aorta were performed. The postoperative course was uncomplicated, but prolonged due to the accompanying diseases. In conclusion, single-vessel revascularization for chronic intestinal ischemia is a safe and sufficient procedure. Interpositioning of a graft and transposition to the aorta have the advantages of infrarenal access with an antegrade blood flow and no kinking of the prosthesis.

Aortography↗
PubMed1985

Regional vasorelaxant selectivity of atrial natriuretic factor in isolated rabbit vessels.

Synthetic atrial natriuretic factor (ANF) exhibited a marked selectivity in its ability to relax isolated rabbit arteries and veins. The aorta, renal and mesenteric arteries and the facial vein were the most sensitive vessels with the more distal arteries and most veins being relatively unresponsive to ANF. All preparations were effectively relaxed by sodium nitroprusside. ANF (up to 10(-7) M) failed to elicit any effect on isolated rabbit right atria or papillary muscles. The profound regional vasorelaxant selectivity of ANF may help to explain the hemodynamic effects of this substance in vivo.

Animals↗
PubMed1996

Ultrasonography and angiographic examination of normal canine liver vessels.

The aim of this study is to provide a description of the ultrasonographic and angiographic anatomy of the hepatic and portal veins in normal dogs. Knowledge of this anatomy is essential for the proper diagnosis and correction of hepatic vessel anomalies like portal systemic shunts. Cranial mesenteric portography was done in 10 adult mongrel dogs to visualize the portal vein and its branches while the hepatic veins were visualized using the transvenous retrograde angiography method. Longitudinal and transverse ultrasound scans of the liver were done in the same dogs in left and right lateral positions in order to determine the best positions for imaging the different liver vessels. The distribution pattern of the hepatic and portal veins could be demonstrated by both ultrasonography and contrast angiography. Hepatic arteries are not usually visualized ultrasonographically. Ultrasound provided dynamic information that could not be obtained by contrast radiography. Super imposition of all vessels in the angiographic studies made the description of the branches of the liver vessels difficult. The results of the present study suggest that both methods may provide important complementary information in the diagnosis and planning of surgical procedures for the correction of vessel anomalies in the canine liver.

Angiography↗
PubMedDate not supplied

Mesenteric arterial steal syndrome secondary to bilateral lumbar sympathectomy.

A case of acute mesenteric ischemia and massive intestinal infarction secondary to bilateral lumbar sympathectomy and without any other apparent precipitating factors is presented. Its characteristics and findings significantly agree with those described as part of the mesenteric arterial steal syndrome. Although this syndrome was originally described as secondary to surgical revascularization of the lower extremities, experimental studies have shown that lumbar sympathectomy, by means of reducing the peripheral vascular resistance in the lower extremities, similarly causes intense hemodynamic alteration of the mesenteric circulation due to the sudeen redistribution of blood flow to the lower limbs at the expense of the mesenteric flow. When marginally compensated occlusive mesenteric arterial disease exists prior to surgery, the sudden fall in the arterial pressure gradients in this vessel can precipitate the occlusion of these arteries, resulting in mesenteric ischemia and intestinal infarction. It has also been suggested that an intense vasospamodic neurogenic reflex in the mesenteric arteries is an important factor in the pathogenesis of this syndrome.

Colon↗
PubMed1980

Angiographic evaluation of vascular changes in ulcerative colitis.

Selective superior and inferior mesenteric angiography was carried out in 25 patients with ulcerative colitis. Vascular changes in angiography were compared with the clinical features of the patients. There was no correlation between vascular changes in angiography and the duration of illness or the extent of involvement. The vascular changes of large vessels, such as increased diameter of the inferior mesenteric artery, had better correlation with the severity or the activity of illness. However, we found that in some cases microcirculatory changes of small vessels of the intestinal wall, such as the findings of capillary brush or loss of normal tapering of vasa recta, still remain in remission of this disease. We assume that this microcirculatory disturbance plays an important role in the pathophysiology of ulcerative colitis.

Adolescent↗

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