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PubMed1983

Comparison of blood vessel wall dimensions in normotensive hypertensive rats by histometric and morphometric methods.

The histometric method is often used in hypertension studies in order to reconstruct, from cross-sectional profiles of vessels in the contracted state, a hypothetical relaxed state of the vessels based on the measured length of the internal elastic lamina (IEL). In this study, the accuracy of the histometric method was tested by comparing values obtained with the histometric method from contracted vessels versus values from morphometric measurements of vessels of the same calibre but maximally relaxed. Mesenteric arteries from spontaneously hypertensive and normotensive Wistar-Kyoto rats were used. We found that the lumen size of the vessels was dependent on the methods of measurement and preparation. Lumen size, determined with the histometric method from contracted vessels, tended to be underestimated mainly because the IEL became shortened during contraction of the vessels. When vessels were prepared by perfusion fixation, a high perfusion flow rate (7.6 ml/min) caused expansion of the lumen in muscular (lumen diameter 120--250 microns) and arteriolar vessels (40--100 microns), but not in the elastic arteries (400--700 microns). The cross-sectional area of the vessel wall, however, remained unchanged when the vessels were either contracted with norepinephrine or expanded with high transmural pressure, so morphometric measurements of the vessel wall and its components can be done on both contracted and relaxed vessels. Our results suggest that the use of the histometric method for the estimation of relaxed lumen size from the contracted vessels is of very limited value. We also suggest that, for an accurate comparison of vessel wall dimensions between hypertensive and normotensive animals, cross-sectional area should be used instead of wall thickness alone.

Animals↗
PubMed1992

Characterization of Na(+)-H+ exchange in segments of rat mesenteric artery.

To develop a technique for measuring Na(+)-H+ exchange activity and intracellular pH (pH(i)) "on line" in resistance vessels, we utilized strips of rat mesenteric arteries loaded with the pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. Strips were held at a fixed length within a 3-ml cuvette, and fluorescence emission was monitored at 530 nm. The spectrofluorimeter was monitored in the ratio mode, and the excitation wavelength was alternated between 440 and 505 nm. Tissues were maintained by perfusing with N-2-hydroxyethylpiperazine-N'-2-ethane-sulfonic acid containing buffers. The introduction of ammonium chloride produced a rapid alkalinization. Washout of ammonium caused rapid acidification. Restoration of pH(i) was Na+ dependent and inhibited by dimethyl amiloride (concentration that produces half-maximal inhibition, K0.5 = 30 microM), features characteristic of Na(+)-H+ exchange. Further studies assessed the transport rate of the exchanger, which averaged 0.19 +/- 0.02 pH U/min (means +/- SE, n = 8). An estimate of the dependence of Na(+)-H+ exchange on external Na+ gave an apparent Michaelis constant for external Na+ of 10 mM and an apparent maximal velocity of 0.1 mM H+/s. Intracellular H+ was found to have a cooperative effect (Hill coefficient = 4) on Na(+)-H+ exchange.

Ammonium Chloride↗
PubMed2001

Non-occlusive mesenteric ischemia: etiology, diagnosis, and interventional therapy.

Non-occlusive mesenteric ischemia (NOMI) compromises all forms of mesenteric ischemia with patent mesenteric arteries. It generally affects patients over 50 years of age suffering from myocardial infarction, congestive heart failure, aortic insufficiency, renal or hepatic disease and patients following cardiac surgery. Non-occlusive disease accounts for 20-30% of all cases of acute mesenteric ischemia with a mortality rate of the order of 50%. Acute abdominal pain may be the only early presenting symptom of mesenteric ischemia. Non-invasive imaging modalities, such as CT, MRI, and ultrasound, are able to evaluate the aorta and the origins of splanchnic arteries. Despite the technical evolution of those methods, selective angiography of mesenteric arteries is still the gold standard in diagnosing peripheral splanchnic vessel disease. In early non-occlusive mesenteric ischemia, as opposed to occlusive disease, there is no surgical therapy. It is known that mesenteric vasospasm persists even after correction of the precipitating event. Vasospasm frequently responds to direct intra-arterial vasodilator therapy, which is the only treatment that has been shown to be effective.

Angiography↗
PubMed2001

Vascular anatomy of the gastrointestinal tract.

The blood supply of the gastrointestinal system has intramural and extramural components. The intramural vascular distribution is generally well developed with plexuses in the different layers of the bowel wall and with specializations in the liver, small intestine and gastroesophageal junction, adapted to the function of these organs. The extramural arterial supply for the oesophagus is derived from the thoracic aorta or its major branches. Blood supply to the abdominal organs is provided by three major unpaired vessels arising from the abdominal aorta, namely the coeliac trunk and the superior and inferior mesenteric arteries. The branches of these vessels form anastomotic systems that provide a rich blood supply to the adjoining organs. In many areas the systems overlap while in other regions linkages are limited. Interrelations and weak points are of significant clinical importance. As well as this, there is a great individual variability in the anatomy of the gastrointestinal vasculature.

Angiography↗
PubMed2003

Superior mesenteric artery syndrome: case report.

Superior Mesenteric Artery Syndrome (SMAS) is caused by trapping of the third part of the duodenum between Superior Mesenteric Artery (SMA) and aorta as result of narrowing of the angle between the two vessels due to acute loss of mesenteric fat which is secondary to rapid weight loss. A fifteen year old caucasian female on a mountain climbing expedition with an acute on chronic upper gastrointestinal obstruction is presented. The diagnosis was confirmed with a barium meal and at surgery, a bypass procedure performed to relieve the obstruction.

Adolescent↗
PubMed2004

The role of CXCL12 in the organ-specific process of artery formation.

CXC chemokine ligand 12 (CXCL12; stromal cell-derived factor-1 [SDF-1]/pre-B-cell growth-stimulating factor [PBSF]) and its receptor CXCR4 are essential for vascularization in the gastrointestinal tract as well as B lymphopoiesis and colonization of bone marrow by hematopoietic cells. However, the mechanism by which CXCL12/CXCR4 functions in blood vessel formation remains elusive. Here, we have found a novel mode of organ vascularization and determined the roles of CXCL12 in these processes. In the developing small intestine, many short interconnecting vessels form between larger superior mesenteric artery (SMA) and the neighboring primary capillary plexus surrounding the primitive gut, and they elongate and become the arteries supplying the small intestine. Mice lacking CXCL12 or CXCR4 lack the interconnecting vessels but have normal venous networks. The mutants lack filopodial extension and intussusception from endothelial cells of SMAs seen in wild-type embryos. CXCR4 is specifically expressed in arteries in the developing mesenteries and its expression is severely reduced in CXCL12-/- embryos. Mice in which CXCR4 is specifically deleted in the endothelium reveal vascular defects identical to those observed in the conventional CXCR4-/- embryos. Together, CXCL12 acts on arterial endothelial cells of SMA to up-regulate CXCR4 and mediate the connection between the larger artery and neighboring capillary plexus in an organ-specific manner.

Animals↗
PubMed1999

Membrane abnormalities of vascular smooth muscle of mesenteric arteries of spontaneous diabetic BB rats.

Mesenteric arteries were isolated from the spontaneous diabetic BB rats, non diabetic BB rats and regular Wistar control rats. Gross morphology indicated that the mesenteric vascular bed of the control Wistar rats had a normal development of mesenteric fat pad around the vessels, while that of the diabetic BB rats showed drastically reduced perivascular fat pad, suggesting greater mobilization of fat for energy consumption in the hyperglycemic state of diabetes mellitus. The perivascular mesenteric fat pad of the non-diabetic BB rats was intermediate between those of the Wistar control and diabetic BB rats. The wet weight of the mesenteric arteries following removal of fat, vein and connective tissues was significantly greater in diabetic BB rats than in the corresponding controls. Microsomal membranes isolated from the mesenteric arteries of diabetic BB rats showed increased alkaline phosphatase and 5'-nucleotidase activities compared to those isolated from the two groups of non-diabetic control rats. Acid phosphatase activities were higher in both BB rat groups compared to the Wistar group. The total Ca2+ uptake by the microsomes of mesenteric arteries in the presence of ATP was not different among three experimental groups, but the ATP dependent active transport of Ca2+ was significantly increased and the passive Ca2+ binding was significantly reduced in diabetic group compared to the other two non-diabetic groups. Our results demonstrate that in the spontaneously diabetic BB rats, alterations in both structural and functional parameters may underline the vascular complications associated with type I diabetes mellitus in humans.

5'-Nucleotidase↗
PubMed1986

Topological structure of rat mesenteric microvessel networks.

Microvascular lengths, diameters, and flow directions were determined in all vessel segments (n = 1303) between bifurcations in three complete rat mesenteric microvessel networks (25 mm2 each) using intravital video- and photomicroscopy. The classification of vessel segments as arteriolar, venular, or av-segments (all segments connecting the arteriolar to the venular tree) was based on purely topological criteria. The topological structure of the networks was analyzed using the Horton-Strahler technique and a new generation scheme. Generation numbers were assigned to the vessel segments on the basis of the number of upstream (in the arteriolar tree) and downstream (in the venular tree) bifurcations. The mean generation number of the av-segments, a characteristic parameter of the generation scheme, reflects the topological structure of the network more accurately than Horton's branching ratio Rb. Both the arteriolar and venular tree of the mesenteric networks were found to be dichotomous branching structures which were neither strictly symmetric nor strictly asymmetric. The topological information obtained was compared to network models generated by different random branching algorithms. The result of this comparison suggests that the network structure changes at a certain generation level. Distal to this generation level, the mesenteric networks resemble a model network generated by random branching at any segment, while the proximal portion is similar to a model allowing random branching at terminal segments only.

Animals↗
PubMed1995

Contractile effects of diaspirin cross-linked hemoglobin (DCLHb) on isolated porcine blood vessels.

The effects of diaspirin cross-linked hemoglobin (DCLHb) on vascular tone were examined in arterial and venous rings isolated from mesenteric, renal, femoral, and pulmonary blood vessels. Rings were placed in organ baths at optimal passive tension in Krebs' solution (37 degrees C) and aerated with a mixture of 95% O2/5% CO2. Vessels were treated with increasing concentrations of DCLHb or an iso-osmotic serum albumin solution. All artery and vein rings contracted in the presence of DCLHb. With the exception of the pulmonary vein, the magnitude of the tension increase with DCLHb was greater in the arteries than in the veins. Removal of the endothelium by scraping or the addition of a nitric oxide synthase inhibitor blocked the DCLHb-induced contraction in the pulmonary artery and vein. DCLHb also significantly reduced basal cyclic guanosine-3-5'-monophosphate in the pulmonary vein. These studies suggest that the constrictor activity of DCLHb is due primarily to inhibition of basal nitric oxide-induced relaxation of the vascular smooth muscle.

Acetylcholine↗
PubMed1989

Regional and species differences in vascular reactivity to extracellular potassium.

In-vitro vasoreactivity to extracellular potassium (Ko+) was tested in isolated human pial and mesenteric arteries as well as basilar and mesenteric arteries from rabbits and rats. Contractions were induced by stepwise increases in [K+]o and were measured isometrically with a force-displacement transducer, in small-volume organ baths. Significant differences between species as well as between regions were found. The threshold of [K+]o for eliciting contraction in human cerebral arteries in hyperosmotic solutions was 10 mM, in rabbit cerebral arteries 17 mM and in rat cerebral arteries 27 mM. The threshold concentration for contraction in mesenteric arteries was significantly higher compared to cerebral arteries in humans and rabbits, but lower in rats: 20 mM in humans, 26 mM in rabbits and 25 mM in rats. In all species the contractile amplitudes were significantly higher in both cerebral and mesenteric arteries when [K+]o was increased under isotonic conditions in the buffer solution than when hyperosomolality was created. This difference increased with increasing hyperosmolality. In hyperosmotic solutions, the EC50 for [K+]o was lower in cerebral and mesenteric arteries from man than in vessels from rabbit and rat. When the solutions were isotonic, this pattern was seen only in mesenteric arteries. It is concluded that significant species and regional differences in vascular responses to [K+]o exist. Considering that [K+]o is increased in cerebral ischaemia, the observed significantly lower threshold for K+-induced contractions in human cerebral arteries may be of importance, especially in human cerebral ischaemic events.

Animals↗
PubMed1998

Influence of tensile strain on smooth muscle cell orientation in rat blood vessels.

Blood vessels are subject to tensile stress and associated strain which may influence the structure and organization of smooth muscle cells (SMCs) during physiological development and pathological remodeling. This study focused on the influence of the major tensile strain on the SMC orientation in the blood vessel wall. Several blood vessels, including the aorta, the mesenteric artery and vein, and the jugular vein of the rat were used to observe the normal distribution of tensile strains and SMC orientation; and a vein graft model was used to observe the influence of altered strain direction on the SMC orientation. The circumferential and longitudinal strains in these blood vessels were measured by using a biomechanical technique, and the SMC orientation was examined by fluorescent microscopy at times of 10, 20, and 30 days. Results showed that the SMCs were mainly oriented in the circumferential direction of straight blood vessels with an average angle of approximately 85 deg between the SMC axis and the vessel axis in all observed cases. The SMC orientation coincided with the principal direction of the circumferential strain, a major tensile strain, in the blood vessel wall. In vein grafts, the major tensile strain direction changed from the circumferential to the longitudinal direction at observation times of 10, 20, and 30 days after graft surgery. This change was associated with a decrease in the angle between the axis of newly proliferated SMCs and that of the vessel at all observation times (43 +/- 11 deg, 42 +/- 10 deg, and 41 +/- 10 deg for days 10, 20, and 30, respectively), indicating a shift of the SMC orientation from the circumferential toward the longitudinal direction. These results suggested that the major tensile strain might play a role in the regulation of SMC orientation during the development of normal blood vessels as well as during remodeling of vein grafts.

Actins↗
PubMed1992

Microvascular circulation of the descending colon in horses.

The microvascular circulation of the descending colon was studied in 5 adult horses, using microangiography and light microscopy combined with gross studies and scanning electron microscopy of vascular replicas. After heparinization, horses were euthanatized, and 3 segments of the descending colon and its mesentery containing 1 vascular arcade were removed from each horse. The fecal balls were gently massaged from the lumen, and the blood was flushed free of the circulation with isotonic NaCl. In 5 segments, the vascular system was injected with a modified radiopaque medium and evaluated radiographically. Specimens examined radiographically also were prepared for histologic examination, using standard methods. Ten segments were injected with 1 of 2 types of plastics and studied grossly or by scanning electron microscopy. Arcuate arteries gave rise to a descending colonic rete that surrounded the vein and supplied numerous descending colonic lymph nodes. The rete also supplied the mesocolon and the descending colonic tissue. Short filamentous vessels arising from the rete directly penetrated the mesenteric tenia to supply an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. Larger vessels arising from either side of the rete divided into the long- and short-terminal arteries that supplied an extensive submucosal plexus, which was continuous around the circumference. The submucosal plexus supplied the mucosa, the tunica muscularis, and the serosa. Vessels running centrifugally from the submucosal plexus formed an intermuscular plexus between the longitudinal and circular muscle layers of the muscularis externa. The intermuscular plexus at the mesenteric angle also was supplied by vessels branching from the short-terminal arteries as they penetrated the muscularis externa.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1997

The use of helical CT and CT angiography to predict vascular involvement from pancreatic cancer: correlation with findings at surgery.

OBJECTIVE: The purpose of this study was to test the accuracy of helical CT with and without CT angiography to predict vascular involvement from pancreatic cancer and correlate the resultant images with findings at surgery. SUBJECTS AND METHODS: Helical CT and CT angiography was done in 84 patients who had adenocarcinoma of the pancreas to refine an integrated CT angiography protocol. Of these patients 38 underwent radical pancreatoduodenectomy. Vessel integrity of the superior mesenteric artery, superior mesenteric vein, and portal vein was assessed prospectively on both axial CT scans and CT angiograms and correlated with findings at surgery and in particular with the ability of the surgeon to dissect the tumor from these vessels along the vascular planes. RESULTS: CT angiograms were obtained in 82 (98%) of 84 studies. Of the 38 patients who underwent radical pancreatoduodenectomy, resection was aborted in 11 (29%) because of vascular encasement, Compared with axial CT images, CT angiography was more accurate at revealing unresectable cases. In all but one of 11 patients with vessel encasement (narrowing of the lumen) revealed on CT angiography, the lesion was unresectable. Vessel encasement was shown in only two of these 11 patients on axial CT images (of these two patients, one underwent tumor resection). The negative predictive value of a resectable tumor was 96% for CT angiography and axial helical CT compared with 70% for axial helical CT images alone (p = .021). CONCLUSION: Helical CT with CT angiography of the pancreas provides useful information about local vascular involvement from pancreatic carcinoma. Compared with conventional axial helical CT, the addition of CT angiography improves radiologists' ability to predict the resectability of pancreatic tumors.

Adenocarcinoma↗
PubMed1995

G-proteins in rat blood vessels--I. Identification.

1. The purpose of this investigation was to identify various types of conventional, low and high molecular weight G-proteins in purified membranes of rat aorta and mesenteric artery. 2. In both blood vessels, immunoblotting of G-proteins using AS/7 antibody specific for Gi-1/2, EC/2 antibody specific for Gi-3 and RM/1 antibody specific for Gs-type conventional G-proteins demonstrated the presence of M(r) 28-43 kDa, M(r) 41 and 48 kDa, and M(r) 36-46 kDa polypeptides, respectively. Immunoblotting using a common antibody (GA/1) for the Gs and Gi alpha-subunits also revealed the existence of multiple polypeptides (M(r) 24-52 kDa) in both aorta and mesenteric artery, some of which were identified by the specific antibodies. The intensity and number of bands detected by most of the antibodies were greater in mesenteric artery than in aorta. 3. Cholera toxin (CT) catalyzed ADP-ribosylation of two Gs alpha (M(r) 43, 46 kDa) in both types of blood vessels with similar intensities of bands. Pertussis toxin (PT), on the other hand, catalyzed ADP-ribosylation of one Gi alpha (M(r) 41 kDa) polypeptide, and the intensity of this band was greater in aorta than in mesenteric artery. The polypeptides ADP-ribosylated by the toxins corresponded with their identification by antibodies. 4. Nitrocellulose blot overlay with [35S]GTP gamma S identified at least seven low molecular weight G-proteins (M(r) 21-30 kDa) in both aorta and mesenteric artery, with greater intensity of bands in mesenteric artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate Ribose↗
PubMed2004

Heterogeneity in the mechanisms of vasorelaxation to anandamide in resistance and conduit rat mesenteric arteries.

1 In order to address mechanistic differences between arterial vessel types, we have compared the vasorelaxant actions of anandamide in resistance (G3) and conduit (G0) mesenteric arteries. 2 Anandamide produced concentration-dependent relaxations of pre-constricted G3 arteries with a maximal response that was significantly greater than seen in G0. 3 The CB1 receptor selective antagonists SR141716A (100 nm) and AM251 (100 nm) caused reductions in the vasorelaxant responses to anandamide in both arteries. Maximal vasorelaxant responses to anandamide were reduced in both arteries after treatment with capsaicin to deplete sensory neurotransmitters (10 microm for 1 h). 4 Vasorelaxation to anandamide was not affected by the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 300 microm) in either artery. Only responses in G3 arteries were sensitive to removal of the endothelium. In G3 vessels only, vasorelaxation to anandamide was reduced by inhibition of EDHF activity with a combination of charybdotoxin (100 nm) and apamin (500 nm) in the presence of L-NAME (300 microm) and indomethacin (10 microm). 5 Antagonism of the novel endothelial cannabinoid receptor (O-1918, 1 microm) caused a reduction in the sensitivity to anandamide in G3 but not G0. 6 G3, but not G0, vessels showed a small reduction in vasorelaxant responses to anandamide after inhibition of gap junctional communication with 18alpha-GA (100 microm). 7 These results demonstrate that there are differences in the mechanisms of vasorelaxation to anandamide between conduit and resistance mesenteric arteries. In small resistance vessels, vasorelaxation occurs through stimulation of vanilloid receptors, CB1 receptors, and an endothelial receptor coupled to EDHF release. By contrast, in the larger mesenteric artery, vasorelaxation is almost entirely due to stimulation of vanilloid receptors and CB1 receptors, and is endothelium-independent.

Animals↗
PubMedDate not supplied

Heterogeneous distribution of [3H]alpha,beta-methylene ATP binding sites in blood vessels.

A radioligand binding assay and autoradiographic localisation of P2X-purinoceptors were carried out in several different blood vessels from rat, guinea-pig and rabbit by using [3H]alpha,beta-methylene ATP ([3H]alpha,beta-MeATP) as the radioligand. The radioligand binding assay on rabbit ear artery showed that the binding process was saturable, and a high density of P2X-purinoceptors was observed. Autoradiographic localisation showed that the specific [3H]alpha,beta-MeATP binding sites were only associated with the smooth muscle of the blood vessels. Semi-quantitation of the autoradiographs revealed significant differences in the densities of P2X-purinoceptors amongst the vessels studied. Generally the medium- and small-sized arteries had higher densities of P2X-purinoceptor than the elastic and large muscular arteries. In some large muscular arteries, such as the rabbit carotid, renal, hepatic and mesenteric, the outer region of vessel had a higher density of receptors than the inner region. The veins in this study were sparsely labelled, except portal veins where the longitudinal and circular layers of muscles were found to have different densities of P2X-purinoceptors. The results from this study provide direct evidence for the existence of P2X-purinoceptors in blood vessels; furthermore, the distribution of the P2X-purinoceptors is consistent with known pharmacological responses elicited by ATP in these vessels.

Adenosine Triphosphate↗
PubMed1996

Mesenteric angioplasty in the treatment of chronic intestinal ischemia.

PURPOSE: This study was undertaken to determine the safety and efficacy of percutaneous transluminal angioplasty (PTA) in the treatment of chronic mesenteric ischemia (CMI) in very high-risk surgical patients. METHODS: Twenty-four focal mesenteric stenoses treated from 1984 to 1994 by PTA in 19 patients with CMI were reviewed. All 19 patients were considered poor surgical candidates. Seventeen patients had classic symptoms of CMI, and two patients had atypical abdominal complaints. Vessels dilated included the superior mesenteric artery (18), celiac artery (3), inferior mesenteric artery (1), aorta-superior mesenteric artery vein graft (1), and aorta-splenic artery vein graft (1). Complete follow-up was possible in all patients, with the exception of one patient who had no symptoms when last seen 17 months after the procedure. RESULTS: PTA was technically successful in 18 of 19 patients (95%) and 23 of 24 stenoses (96%). The lone technical failure resulted in superior mesenteric artery dissection with thrombosis and bowel infarction; the patient died despite emergent laparotomy and revascularization (mortality rate, 5%). Complete symptomatic relief was attained in 15 patients (79%), with follow-up showing continued relief of symptoms for a mean of 39 months (range, 4 to 101 months). Partial symptomatic relief was attained in three patients. Recurrent symptoms developed in three patients (20%) at a mean interval of 28 months (range, 9 to 43 months). Repeat PTA performed in two patients provided good technical results and relief from clinical symptoms. One patient had a symptomatic axillary sheath hematoma that required surgical decompression. CONCLUSIONS: Mesenteric PTA is a valuable treatment option in patients who have CMI and are considered very high operative risks. The initial technical success rate is excellent, with the majority of patients having complete symptomatic improvement and continued relief of symptoms at short-term follow-up.

Aged↗
PubMed1989

Vascular actions of cicletanine.

Vascular wall hypertrophy and enhanced vascular reactivity are characteristic of the hypertensive state. Pharmacologic reversal or prevention of these changes might be of therapeutic benefit. We examined the mechanism by which cicletanine, an antihypertensive vasodilator, induces relaxation of isolated mesenteric resistance arteries and assessed its effects on growth of cultured mesenteric artery myocytes. Initial experiments determined the effect of cicletanine on aortic rings and superior mesenteric arteries isolated from spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats. Cicletanine induced dose-dependent relaxation of pre-contracted segments of both artery types. Aortas of SHR were more sensitive to cicletanine than those of the WKY, while no difference in sensitivity of mesenteric arteries was observed between the two strains. Within-strain comparisons showed that aortas of SHR were more sensitive to cicletanine than mesenteric arteries while no differences were detected in vessels of the WKY. To assess the mechanism of action, the effect of cicletanine on intracellular Ca2+ was determined in mesenteric resistance arteries loaded with fura-2. In 4 of 4 preparations tested, 100 microM cicletanine induced a rapid fall in the level of free ionized Ca2+. When the endothelial lining of superior mesenteric arteries was removed or vessels were pre-treated with either 1 microM propranolol, 0.1 mM ouabain or 5 microM indomethacin, no effect on cicletanine-induced relaxation (10-300 microM) was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗