scholarly journals Microvascular reactivity of in vitro blood perfused juxtamedullary nephrons from rats

1985 ◽  
Vol 28 (5) ◽  
pp. 752-759 ◽  
Author(s):  
Daniel Casellas ◽  
Pamela K. Carmines ◽  
L. Gabriel Navar
Keyword(s):  
Microvascular Reactivity

Altered microvascular reactivity in streptozotocin-induced diabetes in rats

1989 ◽  
Vol 257 (5) ◽  
pp. H1438-H1445 ◽  
Author(s):  
M. A. Hill ◽  
R. G. Larkins
Keyword(s):  
Experimental Diabetes ◽  
Ang Ii ◽  
Prostaglandin I2 ◽  
Short Term ◽  
Third Order ◽  
Basal Diameter ◽  
Microvascular Reactivity ◽  
Vasoconstrictor Response ◽  
Streptozotocin Induced Diabetes

This study examined the effect of short-term streptozotocin-induced diabetes in rats on the response of cremaster muscle arterioles to angiotensin II (ANG II) and vasodilatory prostaglandins. Topically applied ANG II (10(-10) to 10(-6) M) caused significantly greater vasoconstriction of third-order arterioles in diabetic animals in comparison with controls. For example, in response to 10(-6) M ANG II arterioles of the diabetic animals constricted to 43 +/- 10% of basal diameter compared with controls' 67 +/- 6% (P less than 0.05). Furthermore, the magnitude of the secondary vasodilatation after ANG II-induced constriction was decreased in diabetic animals (108 +/- 4 and 131 +/- 9%, P less than 0.025). Cyclooxygenase inhibition resulted in marked arteriolar constriction, with this effect being less evident in diabetic animals. In response to indomethacin (2.8 x 10(-5) M), arterioles of the diabetic animals constricted to 84 +/- 7% of basal diameter compared with 56 +/- 4% in controls (P less than 0.01). Arterioles of the diabetic animals were less responsive to exogenous prostaglandin I2 (PGI2) and PGE2 (10(-12) to 10(-6) M) despite evidence of increased in vitro PGI2 production. The data demonstrate potentiation of the vasoconstrictor response and a diminution of the secondary vasodilator response to ANG II in experimental diabetes. These alterations may be due, in part, to decreased responsiveness of skeletal muscle arterioles to vasodilatory prostaglandins.

Interactions of adenosine A1 and A2areceptors on renal microvascular reactivity

2001 ◽  
Vol 280 (3) ◽  
pp. F406-F414 ◽  
Author(s):  
Akira Nishiyama ◽  
Edward W. Inscho ◽  
L. Gabriel Navar
Keyword(s):  
Receptor Antagonist ◽  
Receptor Blockade ◽  
Microvascular Reactivity ◽  
Adenosine A1 ◽  
Juxtamedullary Nephron ◽  
Renal Microvasculature ◽  
Renal Vascular ◽  
Arteriolar Diameter ◽  
Preglomerular Arterioles

Adenosine vasoconstricts preglomerular arterioles via adenosine A1receptors. Because adenosine also activates adenosine A2receptors, its overall renal vascular actions are complex and not fully understood. The present study was performed to determine the relative contributions of adenosine A1 and A2a receptors to the responsiveness of the renal microvasculature to adenosine. Afferent and efferent arteriolar diameters were monitored in vitro using the blood-perfused rat juxtamedullary nephron preparation. Basal afferent and efferent arteriolar diameters averaged 17.1 ± 0.5 ( n = 35) and 17.8 ± 0.5 ( n = 20) μm, respectively. Superfusion with 0.1 and 1 μmol/l adenosine did not significantly alter afferent and efferent arteriolar diameters; however, 10 μmol/l adenosine significantly reduced afferent and efferent arteriolar diameters (−8.2 ± 0.8 and −5.7 ± 0.6%, respectively). The afferent and efferent arteriolar vasoconstrictor responses to adenosine waned at a dose of 100 μmol/l, such that diameters returned to values not significantly different from control within 2 min. During adenosine A1 receptor blockade with 8-noradamantan-3-yl-1,3-dipropylxanthine (KW-3902: 10 μmol/l), 10 and 100 μmol/l adenosine significantly increased afferent diameter by, respectively, 8.1 ± 1.2 and 13.7 ± 1.3% ( n = 14) and efferent arteriolar diameter by 6.4 ± 1.3 and 9.3 ± 1.2% ( n = 8). The afferent and efferent arteriolar vasodilatory responses to adenosine in the presence of KW-3902 were significantly attenuated by addition of the adenosine A2a receptor antagonist 1,3-dipropyl-7-methyl-8-(3,4-dimethoxystyryl)xanthine (KF-17837: 15 μmol/l, n = 7 and 6, respectively). The addition of KF-17837 alone significantly enhanced afferent ( n = 15) and efferent ( n = 6) arteriolar vasoconstrictor responses to 1, 10, and 100 μmol/l adenosine. These results indicate the presence of adenosine A1 and A2a receptors on afferent and efferent arterioles of juxtamedullary nephrons, such that adenosine A2a receptor-mediated vasodilation partially buffers adenosine-induced vasoconstriction in both pre- and postglomerular segments of the renal microvasculature.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

In Vitro Induction of Crystals of MT Protein by Vinblastine-Colcemid in Mouse Spermatids

1974 ◽  
Vol 32 ◽  
pp. 132-133
Author(s):  
John J. Wolosewick ◽  
John H. D. Bryan
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Nuclear Ring ◽  
Rough Er ◽  
Distal Direction ◽  
In Vitro Induction

Early in spermiogenesis the manchette is rapidly assembled in a distal direction from the nuclear-ring-densities. The association of vesicles of smooth endoplasmic reticulum (SER) and the manchette microtubules (MTS) has been reported. In the mouse, osmophilic densities at the distal ends of the manchette are the organizing centers (MTOCS), and are associated with the SER. Rapid MT assembly and the lack of rough ER suggests that there is an existing pool of MT protein. Colcemid potentiates the reaction of vinblastine with tubulin and was used in this investigation to detect this protein.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Immunoenzymatic demonstration of the simultaneous presence of transferrin, hemopexin and albumin in a same hepatocyte and their ultrastructural localization

1978 ◽  
Vol 36 (2) ◽  
pp. 88-89
Author(s):  
M. Kraemer ◽  
J. Foucrier ◽  
J. Vassy ◽  
M.T. Chalumeau
Keyword(s):  
Plasma Proteins ◽  
Rat Hepatocytes ◽  
Ultrastructural Localization ◽  
Carrier Proteins ◽  
Normal Cells ◽  
Adult Rat ◽  
Adult Rat Hepatocytes ◽  
Monospecific Antisera ◽  
Different Levels

Some authors using immunofluorescent techniques had already suggested that some hepatocytes are able to synthetize several plasma proteins. In vitro studies on normal cells or on cells issued of murine hepatomas raise the same conclusion. These works could be indications of an hepatocyte functionnal non-specialization, meanwhile the authors never give direct topographic proofs suitable with this hypothesis.The use of immunoenzymatic techniques after obtention of monospecific antisera had seemed to us useful to bring forward a better knowledge of this problem. We have studied three carrier proteins (transferrin = Tf, hemopexin = Hx, albumin = Alb) operating at different levels in iron metabolism by demonstrating and localizing the adult rat hepatocytes involved in their synthesis.Immunological, histological and ultrastructural methods have been described in a previous work.

Sem Studies of Co-Cr-Mo Surgical Implant Alloy Corrosion Behavior

1982 ◽  
Vol 40 ◽  
pp. 520-521
Author(s):  
Ann Chidester Van Orden ◽  
John L. Chidester ◽  
Anna C. Fraker ◽  
Pei Sung
Keyword(s):  
Electron Microscopy ◽  
Corrosion Behavior ◽  
Anodic Polarization ◽  
Saline Solution ◽  
Saturated Calomel Electrode ◽  
Physiological Saline ◽  
X Ray ◽  
Physiological Saline Solution ◽  
Scanning Electron

The influence of small variations in the composition on the corrosion behavior of Co-Cr-Mo alloys has been studied using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and electrochemical measurements. SEM and EDX data were correlated with data from in vitro corrosion measurements involving repassivation and also potentiostatic anodic polarization measurements. Specimens studied included the four alloys shown in Table 1. Corrosion tests were conducted in Hanks' physiological saline solution which has a pH of 7.4 and was held at a temperature of 37°C. Specimens were mechanically polished to a surface finish with 0.05 µm A1203, then exposed to the solution and anodically polarized at a rate of 0.006 v/min. All voltages were measured vs. the saturated calomel electrode (s.c.e.).. Specimens had breakdown potentials near 0.47V vs. s.c.e.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Maytansine-Induced Mitotic Arrest in Human Lymphoblasts

1977 ◽  
Vol 35 ◽  
pp. 460-461
Author(s):  
Tai-Te Chao ◽  
John Sullivan ◽  
Awtar Krishan
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Transmission Electron Microscopy ◽  
Tubulin Polymerization ◽  
Vinca Alkaloids ◽  
Antimitotic Activity ◽  
Transmission Electron ◽  
Flow Microfluorometry ◽  
Brain Tubulin

Maytansine, a novel ansa macrolide (1), has potent anti-tumor and antimitotic activity (2, 3). It blocks cell cycle traverse in mitosis with resultant accumulation of metaphase cells (4). Inhibition of brain tubulin polymerization in vitro by maytansine has also been reported (3). The C-mitotic effect of this drug is similar to that of the well known Vinca- alkaloids, vinblastine and vincristine. This study was carried out to examine the effects of maytansine on the cell cycle traverse and the fine struc- I ture of human lymphoblasts.Log-phase cultures of CCRF-CEM human lymphoblasts were exposed to maytansine concentrations from 10-6 M to 10-10 M for 18 hrs. Aliquots of cells were removed for cell cycle analysis by flow microfluorometry (FMF) (5) and also processed for transmission electron microscopy (TEM). FMF analysis of cells treated with 10-8 M maytansine showed a reduction in the number of G1 cells and a corresponding build-up of cells with G2/M DNA content.

Cytochemical Evidence for Presynatic β-Adrenergic Regulation of Secretion in the Developing Rat Submandibular Gland

1977 ◽  
Vol 35 ◽  
pp. 430-431
Author(s):  
L.S. Cutler
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Submandibular Gland ◽  
Neonatal Rat ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Parotid Glands ◽  
Adrenergic Agonist ◽  
Rat Submandibular Gland

Many studies previously have shown that the B-adrenergic agonist isoproterenol and the a-adrenergic agonist norepinephrine will stimulate secretion by the adult rat submandibular (SMG) and parotid glands. Recent data from several laboratories indicates that adrenergic agonists bind to specific receptors on the secretory cell surface and stimulate membrane associated adenylate cyclase activity which generates cyclic AMP. The production of cyclic AMP apparently initiates a cascade of events which culminates in exocytosis. During recent studies in our laboratory it was observed that the adenylate cyclase activity in plasma membrane fractions derived from the prenatal and early neonatal rat submandibular gland was retractile to stimulation by isoproterenol but was stimulated by norepinephrine. In addition, in vitro secretion studies indicated that these prenatal and neonatal glands would not secrete peroxidase in response to isoproterenol but would secrete in response to norepinephrine. In contrast to these in vitro observations, it has been shown that the injection of isoproterenol into the living newborn rat results in secretion of peroxidase by the SMG (1).

Sign in / Sign up

Export Citation Format

Share Document