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PubMed2005

Morphometry of the basal plate superficial uteroplacental vasculature in normal midtrimester and at term.

Uteroplacental (UP) vascular arterial pathology has been associated with pregnancy complications. UP arterial structure has been characterized in placental bed biopsies, at the decidual-myometrial junction. Basal plate UP arteries, which are delivered with the placenta and thus routinely available, are not well characterized. We compared basal plate UP arterial segment morphometry in cases of elective termination of a clinically normal pregnancy at 11 to 24 weeks and of term birth. This study was done in a community-based obstetric service in New York City. UP arteries were identified in placentas of 20 midtrimester (MT) cases and 17 term (TERM) cases. We measured 336 UP artery cross-sections from 46 TERM and 290 MT cases. The basal plate UP artery path length was calculated as the distance between (x,y) coordinates of estimated centers of lumen cross-sections. Basal plate thickness near UP arteries, UP artery cross-sectional areas, vascular luminal eccentricity, and radial standard deviation were directly measured off digital images. Nonparametric and parametric methods compared groups, with P < 0.05 considered statistically significant. In TERM cases, the basal plate thickness near UP arteries was 1.8-fold thinner (P = 0.002) and mean basal plate path lengths were 2.13-fold shorter (P < 0.0001) than in MT cases. Mean TERM UP artery cross-sectional area was 3.15-fold larger, the major axis was 1.95-fold larger, and the minor axis was 1.75-fold larger than in MT arteries (P = 0.001 to 0.008). Our data demonstrate that basal plate UP arteries (delivered with the placenta) are less tortuous, with shorter path lengths and larger areas as gestation advances. Normative morphometric data may allow improved diagnostics of placentas from complicated pregnancies.

Arteries↗
PubMed1996

A stereotaxic template atlas of the macaque brain for digital imaging and quantitative neuroanatomy.

A stereotaxic brain atlas of the longtailed macaque (Macaca fascicularis) is presented in a format suitable for use as a template atlas of the macaque brain. It includes most of the brain segmented to show the boundaries of landmark structures such that every point in the brain can be represented by a unique set of coordinates in three-dimensional space and ascribed unambiguously to one and only one primary structure. More than 400 structures are represented, including 360 volumetric structures, which constitute the substance of the brain, and 50 superficial features. To facilitate use with ventriculography, magnetic resonance imaging, and other noninvasive imaging techniques, the stereotaxic space is referenced to internal landmarks, viz., the anterior commissure and posterior commissure; the center of the anterior commissure at the midline is the origin of the stereotaxic axes. Reference of stereotaxis to this bicommissural space facilitates structural comparison with human brain atlases, which are commonly referenced to the biocommissural line. It also facilitates comparison of brains of different nonhuman primate species by providing a template brain against which to compare size and internal variability. Thirty-three coronal sections at 1-mm intervals from the spinomedullary junction to the rostral extreme of the caudate nucleus show most structures of the hindbrain, midbrain, and subcortical forebrain. Separately, four side views and 16 coronal sections show cortical structures. Structures are represented by outlines of their boundaries and labeled according to NeuroNames, a systematic English nomenclature of human and nonhuman primate neuroanatomy. Abbreviations are based on a protocol designed to facilitate cross-species comparisons. Instructions are provided for: (1) locating sites from the Template Atlas in the conventional stereotaxic space of an experimental animal, (2) locating sites identified by conventional stereotaxis in the Template Atlas, and (3) using the Template Atlas to collate, compare, and display image information (e.g., labeled cells, recording sites, stimulation sites, lesions) from multiple animals.

Animals↗
PubMed1994

Endopyelotomy and pyeloplasty: face to face.

46 symptomatic adult patients with documented ureteropelvic junction obstruction were treated with pyeloplasty (n = 23) or endopyelotomy (n = 23). Basic characteristics in both the groups were comparable. The technical aspects, complications and outcome, in the form of improvement in function and drainage patterns, were compared in both the groups. Endopyelotomy enjoyed the significant advantages of a shorter operating time and hospital stay, and obviously better cosmetic acceptance. The major complications in the endopyelotomy groups were related to external drainage and secondary infection in the form of fever, secondary hemorrhage and slippage of tubes in 44, 9 and 13% of cases, respectively. Complications associated with pyeloplasty were prolonged urinary leak, wound infection and urinary tract infection in 12, 17 and 22% of cases, respectively. Using 99Tc-DTPA diuretic scan, an improvement of more than 10% in split renal function could not be documented for any case from either group. In none of the patients did the function deteriorate either. Of all evaluable cases, only 1 in the pyeloplasty group showed a persistent obstructive pattern. The rest all demonstrated adequate drainage across the ureteropelvic junction. Overall in 12 cases (8 pyeloplasty, 4 endopyelotomy) drainage could not be determined postoperatively due to poor radionuclide uptake. A nephrostogram and/or pressure flow study, however, demonstrated a nonobstructive pattern in all these patients. It is concluded that endopyelotomy scores over pyeloplasty with a shorter operating time and hospital stay. The complication rate and outcome following surgery, however, are comparable in both the groups. Using external drainage following endopyelotomy, early resumption of work, however, could not be obtained.

Adolescent↗
PubMed1999

Examination of the transverse tubular system in living cardiac rat myocytes by 2-photon microscopy and digital image-processing techniques.

The transverse tubular system (t-system) of cardiac muscle is a structure that allows rapid propagation of excitation into the cell interior. Using 2-photon molecular excitation microscopy and digital image-processing methods, we have obtained a comprehensive overview of the t-system of rat ventricular myocytes in living cells. We show that it is possible to quantify the morphology of the t-system in terms of average local tubule diameter, branching pattern, and local abundance of the t-system by immersing living myocytes in a dextran-linked fluorescein solution. Our data suggest that previous electron microscopic examinations of t-system structure have underestimated both the geometric complexity of the t-system morphology and the fraction of cell volume occupied by the t-system (3.6% in this species). About 40% of tubules occur between Z-lines, and the t-tubule diameter is 255+/-0.85 nm (mean+/-SEM). The t-tubules leave the outer surface of the cell in an approximately rectangular array; however, at some points junctions between the t-tubules and the surface membrane are missing. In view of the complexity of the t-system apparent from our images, we propose that the t-system be renamed the "sarcolemmal Z rete." The methods presented here are generally applicable to the quantification of the sarcolemmal Z rete and other structures within cells by fluorescence microscopy in a variety of cell types.

Animals↗
PubMed1977

A new method for quantifying ventricular regularization during atrial fibrillation.

Atrial fibrillation (AF) characteristically results in random variation of the intervals between successive ventricular depolarizations. However, when a patient with AF is treated with excessive amounts of digitalis, regular junctional rhythms may occur. The detection of "regularization" of the ventricular rhythm in patients with AF may signal early digitalis toxicity. In this paper, we describe a new method for quantifying the extent of ventricular regularization by the statistical analysis of the intervals between successive ventricular depolarizations (R-R intervals). This method yields a single index (Z score) which reflects the degree to which a sequence of R-R intervals deviates from a random distribution. Simulation studies demonstrate that our method is sensitive to "regularization" of as little as two to four percent of R-R intervals, even when equal intervals occur in small groups that might easily escape detection by visual electrocardiographic interpretation. Analysis of records from six nondigitalized subjects in AF shows that the sequence of R-R intervals is usually random, or very nearly so. Records obtained from the same patients when digitalized often demonstrate more regularized activity, reflected by an index (Z score) which is higher than expected from chance deviation if a random process is assumed. Preliminary data also suggeest that exercise is associated with substantial regularization of ventricular depolarization.

Atrial Fibrillation↗
PubMed1998

Development of the endolymphatic sac and duct in the Japanese red-bellied newt, Cynops pyrrhogaster.

The development and maturation of the endolymphatic sac (ES) and duct (ED) were studied in the newt Cynops pyrrhogaster. The ES first appears as an oval capsule at the dorsal-medial tip of the otic vesicle at stage 39, about 11 days after oviposition. The ES consists of polymorphous epithelial cells with a minimum of cytoplasm. The intercellular space (IS) between the epithelial cells is narrow and has a smooth surface. At stage 44, the size of the ES increases as many vacuoles in the IS become filled. At stage 46, 18 days after oviposition, the ES elongates markedly and a slit-like lumen is found in the ES. The epithelium contains a few cell organelles which are scattered in the cytoplasm. The vacuoles in the IS are fused, which expands the IS. Two days later (stage 48), floccular material (endolymph) is present in the expanded lumen. The IS dilates and has a wide and irregular appearance. At stage 50, approximately 26 days after oviposition, the ES extends and expands significantly and crystals (otoconia) can now be seen in the widened lumen of the ES. The cytoplasm of the cuboidal epithelial cells contains an abundance of vesicles surrounded by ribosomes and Golgi complexes. Intercellular digitations are formed in the expanded IS. At stage 54, the ES forms a large bellow-like pouch. Numerous otoconia accumulate in the lumen. Free floating cells and cell debris can be seen in the lumen at this stage. The epithelial cells contain numerous cytoplasmic organelles which are evenly distributed in the cytoplasm. Granules are found in the apical and lateral cytoplasm. The IS is loose and displays a labyrinthine appearance. The primitive ED first appears as a connection between the ES and the saccule but no lumen is present inside at stage 39. At stage 46, a narrow lumen is formed in the ED, which corresponds to the formation of the ES lumen. At stage 50, as the ED extends, floccular material is seen in the lumen. At stage 54, the ED bears numerous microvilli on its luminal surface. Otoconia and endolymph are present in the ED. Tight junctions between the epithelial cells are formed at stage 46. A fully developed intercellular junctional complex is produced at stage 54. Based on the development of the ES and ED, the maturation of function of the ES and ED are discussed.

Animals↗
PubMedDate not supplied

Efficacy of MR angiography in the detection and characterization of occlusive disease in the vertebrobasilar system.

PURPOSE: The purpose of this work was to determine the efficacy of MR angiography (MRA) in the detection and characterization of occlusive disease in the vertebrobasilar system. METHOD: We retrospectively reviewed the posterior circulation registry of our institution to select 42 consecutive patients with posterior circulation ischemic symptoms who underwent both MRA and angiography. The extracranial vertebral arteries (ECVAs) were examined by two-dimensional time-of-flight MRA above the C6 level, and the intracranial vertebral arteries (ICVAs) and basilar arteries (BAs) were examined by three-dimensional time-of-flight MRA. Sixty-two ECVAs, 63 ICVAs, and 39 BAs were examined by the readers. RESULTS: Occlusive disease was seen on angiography in 22 of the 42 patients. The sensitivity and specificity values for detection of lesions in 12 ECVA, 19 ICVA, and 12 BA abnormalities were as follows: ECVA, 92 and 96% for Reader A and 100 and 90% for Reader B; ICVA, 84 and 93% for Reader A and 74 and 82% for Reader B; and BA, 100 and 88% for Reader A and 100 and 78% for Reader B. For ICVA, the sensitivity of MRA was less than that of angiography because of lesions missed by the readers at the junctional area of the extra-and intracranial MRA. MRA accurately characterized 9 of the 12 (75%) ECVA, 10 of the 19 (43%) ICVA, and 11 of the 12 (92%) BA lesions. CONCLUSION: MRA is an effective method for detection of occlusive lesions in the ECVAs and BAs. Clinically important lesions can be missed by MRA in the ICVA. MRA is more accurate in characterization of occlusive lesions in BAs than in ECVAs or ICVAs.

Aged↗
PubMed2006

Motor-unit synchrony within and across compartments of the human flexor digitorum superficialis.

An interesting feature of the muscular organization of the human hand is that the main flexors and extensors of the fingers are compartmentalized and give rise to multiple parallel tendons that insert onto all the fingers. Previous studies of motor-unit synchrony in extensor digitorum and flexor digitorum profundus indicated that synaptic input to motor neurons supplying these multitendoned muscles is not uniformly distributed across the entire pool of motor neurons but instead appears to be partially segregated to supply subsets of motor neurons that innervate different muscular compartments. Little is known, however, about the organization of the synaptic inputs to the motor neurons supplying another multitendoned finger muscle, the flexor digitorum superficialis (FDS). Therefore in this study, we estimated the extent of divergence of last-order inputs to FDS motor neurons by measuring the degree of short-term synchrony among motor units within and across compartments of FDS. The degree of synchrony for motor-unit pairs within the same digit compartment was nearly twofold that of pairs of motor units in adjacent compartments and more than fourfold that of pairs in nonadjacent compartments. Therefore like other multitendoned muscles of the hand, last-order synaptic inputs to motor neurons supplying the FDS appear to primarily supply subsets of motor neurons innervating specific finger compartments. Such an organization presumably enables differential activation of separate compartments to facilitate independent movements of the fingers.

Action Potentials↗
PubMed1995

NADPH-diaphorase-positive nerve fibers in smooth muscle layers of opossum esophagus: gradients in density.

Nitric-oxide-releasing nerves regulate esophageal smooth muscle function. The density of such nerve fibers may differ in the different functional parts of the esophagus. We used both inspection and gray-scale analysis of digitized images to seek differences in density of such nerve fibers, stained for reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-diaphorase), between esophageal body and esophago-gastric sphincter and between smooth muscle layers in the opossum esophagus. Sections of Swiss roll preparations of the entire organ were stained for NADPH-diaphorase and for immunoreactivity to vasoactive intestinal polypeptide (VIP), calcitonin gene-related peptide (CGRP), galanin (GAL), substance P (SP) and constitutive nitric oxide synthase (cNOS). In the circular muscle layer, NADPH-diaphorase-positive fibers were most abundant at the cephalic end of the esophageal body with a significant decline toward and through the esophago-gastric sphincter. In the longitudinal muscle layer and the longitudinally-oriented muscularis mucosae, NADPH-diaphorase-positive nerve fibers were most abundant at the esophago-gastric sphincter with a significant decline toward and through the striated-smooth muscle junction. cNOS immunoreactivity co-localized with NADPH-diaphorase activity. Fibers stained for CGRP immunoreactivity were distributed like the NADPH-diaphorase-positive fibers. Fibers stained for immunoreactivity to the other peptides (VIP, GAL, SP) showed no clear differences in distribution along the esophagus in any of the muscle layers.

Amino Acid Oxidoreductases↗
PubMed2006

[Systemic sclerosis and cancer].

The combination of skin induration with clinical features such as dyspnea, facial telangiectasia, digital infarctions and/or dysphagia supports the diagnosis of systemic sclerosis. The oesophageal dysmotility is associated with symptoms which may delay the diagnosis of gastro-oesophageal cancer. Herein we report a case of long standing systemic sclerosis with heartburn and dysphagia symptoms which were monitored closely. Unfortunately, these symptoms delayed the diagnosis of gastric adenocarcinoma. This case prompted us to review the evidence of the association of cancer and systemic sclerosis and if any oncologic evaluation is required during the follow-up of patients affected with systemic sclerosis.

Adenocarcinoma↗
PubMed2003

Laryngeal elevation achieved by neuromuscular stimulation at rest.

During swallowing, airway protection is achieved in part by laryngeal elevation. Although multiple muscles are normally active during laryngeal elevation, neuromuscular stimulation of select muscles was evaluated to determine which single muscle or muscle pair best elevates the larynx and should be considered during future studies of neuromuscular stimulation in dysphagic patients. Hooked-wire monopolar electrodes were inserted into mylohyoid, thyrohyoid, and geniohyoid muscle regions in 15 healthy men selected for having a highly visible thyroid prominence for videotaping. During trials of single, bilateral, and combined muscle stimulations, thyroid prominence movements were video recorded, digitized, and normalized relative to elevation during a 2-ml water swallow. Individual muscle stimulation induced approximately 30% of the elevation observed during a swallow and approximately 50% of swallow velocity, whereas paired muscle stimulation resulted in approximately 50% of the elevation and approximately 80% of the velocity produced during a swallow. Paired muscle stimulation produced significantly greater elevation than single muscle stimulation and could assist with laryngeal elevation in dysphagic patients with reduced or delayed laryngeal elevation.

Adolescent↗
PubMed1996

Localization of HIV-1 RNA in mammalian nuclei.

The Rev protein of human immunodeficiency virus type 1 (HIV-1) facilitates the nuclear export of unspliced and partially spliced viral RNAs. In the absence of Rev, these intron-containing HIV-1 RNAs are retained in the nucleus. The basis for nuclear retention is unclear and is an important aspect of Rev regulation. Here we use in situ hybridization and digital imaging microscopy to examine the intranuclear distributions of intron-containing HIV RNAs and to determine their spatial relationships to intranuclear structures. HeLa cells were transfected with an HIV-1 expression vector, and viral transcripts were localized using oligonucleotide probes specific for the unspliced or spliced forms of a particular viral RNA. In the absence of Rev, the unspliced viral RNAs were predominantly nuclear and had two distinct distributions. First, a population of viral transcripts was distributed as approximately 10-20 intranuclear punctate signals. Actinomycin D chase experiments indicate that these signals represent nascent transcripts. A second, stable population of viral transcripts was dispersed throughout the nucleoplasm excluding nucleoli. Rev promoted the export of this stable population of viral RNAs to the cytoplasm in a time-dependent fashion. Significantly, the distributions of neither the nascent nor the stable populations of viral RNAs coincided with intranuclear speckles in which splicing factors are enriched. Using splice-junction-specific probes, splicing of human beta-globin pre-mRNA occurred cotranscriptionally, whereas splicing of HIV-1 pre-mRNA did not. Taken together, our results indicate that the nucleolus and intranuclear speckles are not involved in Rev regulation, and provide further evidence that efficient splicing signals are critical for cotranscriptional splicing.

Biological Transport↗
PubMed1983

Vagal mechanoreceptors located in the lower oesophageal sphincter of the cat.

In anaesthetized cats, sixty-two vagal sensory units with afferent endings in the lower oesophageal sphincter were recorded by means of extracellular glass micro-electrodes implanted in the nodose ganglion. All the receptors had non-medullated fibres, with conduction velocities ranging from 0.8 to 1.2 m/s. From the direct stimulation of the lower oesophageal sphincter, three types of mechanoreceptors were identified. Thirty-one were activated by natural stimuli:tonic contraction of the sphincter and distension elicited by the passage of a bolus. Artificial stimulation effected by digital compression was also effective. These receptors were similar to muscular endings already described in the digestive tract. Their main characteristic, i.e. their slow adaptation, suggests that they act as sensors of sphincter opening and closure. This was corroborated by observations obtained during distension of the cervical or thoracic oesophagus; a maximum decrease occurred in the lower oesophageal sphincter mechanoreceptor discharge when the distension was produced between 9 and 12 cm from the lower oesophageal sphincter. Twenty-nine endings were found in the superficial layers (mucosae). Contrary to the muscular receptors, the mucosal receptors were not affected by normal contractions or distensions of the lower oesophageal sphincter. They were activated only by strong stimuli like digital compression or distension achieved with a balloon. In addition, mucosal stroking was a potent stimulus. Whatever the stimulus used, the mucosal receptors showed rather rapidly adapting discharges. These receptors should be considered to be sensors of bolus consistency. Two mechanoreceptors, located in the serous membrane of the lower oesophageal sphincter, were identified by touching or by stretching. Their discharges showed that they belonged to the rapidly adapting type. A comparison of the three types of receptors found in the lower oesophageal sphincter is made with known digestive endings and their possible role is discussed.

Action Potentials↗
PubMed1996

Experimental laparoscopic aortic aneurysm resection and aortobifemoral bypass.

The purpose of the present study was to develop a technique for laparoscopic aortic aneurysm resection and aortobifemoral bypass through an anterior retroperitoneal approach. Eight piglets weighing between 75 and 80 kg were anesthetized. The concepts of Shumacker's anterior retroperitoneal exposure of the aorta were modified to allow laparoscopic exposure of the aorta in the first four animals. The other four animals were treated as if they had an aortic aneurysm. The piglet is placed in a supine position. The first port (1.5 cm) is placed laterally near the tip of the 12th rib. As much dissection of the retroperitoneum as possible is performed digitally through this port. A second port (1.5 cm), through which an abdominal lift device and a peritoneal retractor will be inserted, is created superiorly just lateral to the left rectus sheath, and a plane is developed that joins the original dissected space. Two other ports (1.5 cm) are placed in the flanks in a plane inferosuperior to the first port. The surgeon will use two of the lateral ports, and the third one is for the laparoscope. The last two ports (1.5 cm), from which the assistant will work, are placed in the left paramedian region. Using this approach, we performed four aortobifemoral bypasses in an average of 4.5 h after conventional i.v. heparinization (100 IU/kg) with minimal bleeding (blood loss < 550 cc). After infrarenal aortic cross-clamping, the external iliac and caudal vessels were either tied with 0-chromic or occluded with laparoscopic bull-dogs. The aorta was opened, and bleeding lumbar arteries and the aortoiliac junction were sutured with 4-0 Prolene. The vascular graft was sutured end-to-end to the aortic stump with running 4-0 Prolene. Tunneling to the femoral regions was made easy by the position of the animal. No mortality occurred before sacrifice of the animals. This laparoscopic animal model paves the way for human aortic aneurysm replacement.

Animals↗
PubMed1982

[Left ventricular outer wall motion in hypertrophic cardiomyopathy assessed by biplane coronary cineangiograms].

Left ventricular wall motion in patients with hypertrophic cardiomyopathy may show a characteristic movement since this condition is characterized by a disproportionate thickening of the wall and disorientation of myocardial muscle fibers. Biplane coronary cineangiograms were performed in 5 patients with hypertrophic cardiomyopathy and the spatial distance between the bifurcation of the left coronary artery was calculated using a digitizer-computer-plotter system as a measure of epicardial chord segment length. Systolic shortening of the segment was calculated as (LECG R--LES)/ECG R x 100 (%), where LECG R and LES represent segment lengths at the R wave of the electrocardiogram and at the end of systole, respectively. The value amounted 6.9 +/- 5.1 (+/- SD)% on the average which was significantly lower than the previously described values (9.0 +/- 4.1%) in 19 normal subjects. In all of 3 segments at the apex, systolic shortening showed nearly zero or negative indicating systolic expansion. Reduced shortening in patients with hypertrophic cardiomyopathy observed at the epicardial segment in the present study might be a reflection of geometrical difference between endocardial and epicardial segments because shortening of the epicardium will be reduced even the endocardium shortens considerably if the thickness of the wall is markedly increased. Anterior surface of the interventricular septum might be unable to shorten freely along the long axis since it is a junction of trifurcation among right and left ventricular free walls and the interventricular septum if these three walls are thickened. The present study indicated that shortening characteristics in the outer myocardium in patients with hypertrophic cardiomyopathy is markedly impaired possibly due to geometrical difference between endocardial and epicardial segments caused by marked thickening of the wall and also due to the degeneration or disorientation of myocardial fibers.

Cardiomyopathy, Hypertrophic↗
PubMed1984

Fine structure of the interdigital membranes during the morphogenesis of the digits of the webbed foot of the duck embryo.

Fine structural study of interdigital membranes during formation of the digits of the duck foot reveals that the interdigital necrosis is accompanied by a high deposition of collagenous material in the epithelio-mesenchymal interface, rupture of the basal lamina and detachment of ectodermal cells into the amniotic sac. These changes are similar to those observed in the regressing interdigital membrane of the chick although their intensity and temporal extension are less pronounced in the duck. It is suggested that these changes account for the disappearance of the marginal zone of the duck interdigital membranes. The possible causal relationship between the different structural changes are discussed.

Animals↗
PubMed1997

Structural and functional analyses of human cerebral cortex using a surface-based atlas.

We have analyzed the geometry, geography, and functional organization of human cerebral cortex using surface reconstructions and cortical flat maps of the left and right hemispheres generated from a digital atlas (the Visible Man). The total surface area of the reconstructed Visible Man neocortex is 1570 cm2 (both hemispheres), approximately 70% of which is buried in sulci. By linking the Visible Man cerebrum to the Talairach stereotaxic coordinate space, the locations of activation foci reported in neuroimaging studies can be readily visualized in relation to the cortical surface. The associated spatial uncertainty was empirically shown to have a radius in three dimensions of approximately 10 mm. Application of this approach to studies of visual cortex reveals the overall patterns of activation associated with different aspects of visual function and the relationship of these patterns to topographically organized visual areas. Our analysis supports a distinction between an anterior region in ventral occipito-temporal cortex that is selectively involved in form processing and a more posterior region (in or near areas VP and V4v) involved in both form and color processing. Foci associated with motion processing are mainly concentrated in a region along the occipito-temporal junction, the ventral portion of which overlaps with foci also implicated in form processing. Comparisons between flat maps of human and macaque monkey cerebral cortex indicate significant differences as well as many similarities in the relative sizes and positions of cortical regions known or suspected to be homologous in the two species.

Anatomy, Cross-Sectional↗
PubMed1995

The relationship between density of alpha-adrenoceptor binding sites and contractile responses in several porcine isolated blood vessels.

1. The aim of this study was to investigate constrictor alpha-adrenoceptors in three isolated blood vessels of the pig, the thoracic aorta (TA), the splenic artery (SA) and marginal ear vein (MEV) and then compare the functional response with the densities of alpha 1- and alpha 2-adrenoceptor binding sites in these and several other porcine vascular tissues, palmar common digital artery (PCDA), palmar lateral vein (PLV) and ear artery (EA). 2. Noradrenaline (NA), phenylephrine (PE) and UK14304 (all at 0.03-10 microM) elicited concentration-dependent contractions in the TA and MEV, with a rank order of potency of UK14304 > NA > PE. UK14304 produced maximal responses which were 58% (TA) and 65% (MEV) of that of NA. In the SA, UK14304 and PE produced maximal responses which were less than 10% and 50% of the NA-induced maximal response respectively, with an order of potency of NA > PE. In the SA, NA-induced contractions were competitively antagonized by prazosin (pA2 = 8.60 +/- 0.15). Further, rauwolscine (1-10 microM) antagonized NA-induced contractions with an apparent pKB of 6.09 +/- 0.11 (n = 6), indicating an action at alpha 1-adrenoceptors. The combination of the two antagonists at concentrations selective for alpha 1- (0.1 microM) and alpha 2-adrenoceptors (1 microM) had no greater effect than either antagonist alone. This suggests that the SA expresses only post-junctional alpha 1-adrenoceptors. 3. In the TA, prazosin produced non-parallel shifts in the NA-induced CRC and this was also observed with rauwolscine, where reductions in the maximal responses were also observed. In the MEV, prazosin was largely inactive in antagonizing NA-induced contractions. In both these vessels a combination of these two antagonists had a greater effect than either alone, indicating the presence of functional alpha 1- and alpha 2-adrenoceptors. The post-junctional alpha 2-adrenoceptors in all of these vessels were resistant to prazosin, suggesting the alpha 2-adrenoceptor to be of the alpha 2A/2D subtype. The expression of functional alpha 2-adrenoceptors was MEV > TA > PLV > PCDA > SA. 4. In radioligand binding studies using TA P2 pellet membranes, [3H]-prazosin and [3H]-RX821002 ([1,4-[6,7(n)-3H] benzodioxan-2-methoxy-2-yl)-2-imidazole) labelled different high affinity sites, and in competition studies using identical membranes corynanthine displaced [3H]-prazosin with 10 fold higher affinity than rauwolscine, indicating that [3H]-prazosin was selectively binding to alpha 1-adrenoceptor sites. Further, rauwolscine displaced [3H]-RX821002 with approximately 100 fold greater affinity compared to corynanthine, which is indicative of selective alpha2-adrenoceptor binding.5. Separation of the P2 pellet into plasma membrane and mitochondrial fractions was carried out using a differential sucrose density gradient. [3H]-prazosin and [3H]-RX821002 binding sites were found in both the plasma membrane and mitochondrial fractions.6. In saturation studies all tissues produced single site saturation curves with no difference in the Kd(range 0.13-0.20nM) of the alpha1-adrenoceptor sites for [3H]-prazosin. However, there was considerable variation in Bmax of alpha 1-adrenoceptor sites; the highest density was found in the TA (397.9 =/- 52.7 fmol mg-1, n = 4), followed by the PCDA (256.7 +/- 22.7 fmol mg-1, n = 4), the PLV and SA having approximately equal density (143.6 +/- 3.9 and 159.1 +/- 7.0 fmol mg-1 respectively, n = 4 for both), followed bythe EA (91.3 +/- 10.5 fmol mg-1, n = 3) and the MEV had the lowest density (48.9 +/- 11.4 fmol mg-1,n = 3).7. In saturation studies using [3H]-RX821002, all tissues produced single site saturation curves with no differences in the Kd values (range 1.31 +/- 2.16 nM) but the highest densities were found in the TA and MEV (545.3 +/- 36.2 and 531.0 +/- 40.9 fmol mg-1 respectively), followed by the PLV (418.4 +/- 39.4 fmol mg-1), then the EA (266.3 +/- 40.0 fmol mg-1), and low densities of [3H]-RX821002 binding being found in the PCDA and SA (155.9 +/- 18.1 and 117.5 +/- 19.3 fmol mg-1 respectively).8. The pattern of binding site distribution for alpha l- and alpha 2-adrenoceptors is in reasonable agreement with functional studies carried out in these porcine vascular tissues; the TA has the highest densities of alpha 1-and alpha2-adrenoceptors; in the SA and PCDA there is a predominance (although small) of alpha l-adrenoceptor binding sites, the reverse of which is observed both in the PLV and MEV (i.e. greater density of alpha2-adrenoceptor sites). Thus, it would appear that alpha 1- and alpha2-adrenoceptor densities play a role in the expression of functional responses via these receptor subtypes; although it is interesting to note that the SA did have a small density of alpha 2-adrenoceptor binding sites, no functional response was observed after alpha2-adrenoceptor activation.

5'-Nucleotidase↗