scholarly journals Functional consequences of agonist-mediated state transitions in the cholinergic receptor. Studies in cultured muscle cells.

1979 ◽  
Vol 254 (9) ◽  
pp. 3315-3325 ◽  
Author(s):  
S Sine ◽  
P Taylor
Keyword(s):  
Muscle Cells ◽  
Cholinergic Receptor ◽  
State Transitions ◽  
Functional Consequences

Contraction and [3H]QNB binding in collagenase isolated fundic smooth muscle cells

1983 ◽  
Vol 245 (2) ◽  
pp. G270-G276
Author(s):  
E. R. Seidel ◽  
L. R. Johnson
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Cholinergic Receptor ◽  
Gastric Fundus ◽  
Cholinergic Receptors ◽  
Muscarinic Agonists ◽  
Muscarinic Cholinergic Receptors ◽  
Binding Characteristics ◽  
Muscarinic Cholinergic

Smooth muscle cells from the guinea pig gastric fundus were isolated by successive collagenase digestions. Tritiated quinuclidinyl benzilate [( 3H]QNB) was used to study the binding characteristics of the muscarinic cholinergic receptors on these cells. Each cell bound 8.3 X 10(-19) mol of QNB, and a concentration of QNB of 0.19 nM was required to label one-half of the binding sites. This suggests a concentration of about 500,000 muscarinic cholinergic receptors per smooth muscle cell. The muscarinic cholinergic receptor antagonists atropine and scopolamine inhibited QNB binding with a 50% inhibiting concentration (IC50) in the nanomolar range, whereas the agonists acetylcholine (ACh), oxotremorine, and carbamylcholine had IC50S in the micromolar range. Hill coefficients (nH) for antagonists approached unity, but agonists displayed fractional nH. Exposure of cells to cholinergic muscarinic agonists resulted in dose-dependent decreases in cell length. The concentration of agonist required to induce half-maximal contractions (ED50) was 8.3 X 10(-12) M for ACh and 6.3 X 10(-13) M for oxotremorine. Atropine (10(-9) M) decreased the sensitivity to ACh, increasing the ED50 for ACh-induced contractions to 1.2 X 10(-10) M. These results suggest the existence of muscarinic receptor heterogeneity for cholinergic agonists but not for antagonists.

Increased Expression of Protease Activated Receptor-2 (PAR-2) in Balloon-Injured Rat Carotid Artery

1999 ◽  
Vol 81 (05) ◽  
pp. 808-814 ◽  
Author(s):  
Michael D’Andrea ◽  
Lawrence de Garavilla ◽  
Wai-man Cheung ◽  
Patricia Andrade-Gordon ◽  
Bruce Damiano
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Injury ◽  
Smooth Muscle Actin ◽  
Balloon Catheter ◽  
Muscle Cells ◽  
Nuclear Antigen ◽  
Protease Activated Receptors ◽  
Functional Consequences ◽  
The Media

SummaryProtease-induced cell signaling is mediated by specific receptors such as the emerging family of protease activated receptors (PARs). Since proteases are involved in various aspects of vascular injury, we assessed expression of PAR-2, a protease-activated receptor closely related to the thrombin receptor (PAR-1) but activated by an unknown protease, in vascular injury. Rat carotids were subjected to balloon-catheter injury and perfusion fixed at 1, 3, 7 or 14 days after injury. Sections of injured and normal carotid arteries were immunohisto-chemically labeled with a polyclonal antibody raised against the N-terminal residues 37-53 of human PAR-2. Sections were also labeled with antibodies to factor VIII-related antigen, smooth muscle actin and a proliferating cell nuclear antigen (PCNA). In normal vessels, PAR-2 labeling was diffuse and patchy in medial smooth muscle and endothelium. At one and three days after injury, before appearance of neointima, PAR-2 labeling increased in cells adjacent to damaged or necrotic smooth muscle cells. In addition, proliferating adventitial myofibroblasts labeled strongly for PAR-2. At 7 and 14 days after injury, the media and neointima of injured vessels had increased PAR-2 labeling which was most intense at the luminal edge of the neointima. Double immunohistochemical labeling confirmed the greatest expression of PAR-2 in areas with the greatest density of PCNA-positive cells. In addition, PAR-2 mRNA localization using in situ hybridization paralleled PAR-2 expression. The data suggest an upregulation of PAR-2 in response to vascular injury which is associated with medial smooth muscle damage, proliferating adventitial myofibroblasts and smooth muscle cells of the neointima, particularly those at the proliferating luminal edge of the neointima. Possible functional consequences of this receptor upregulation and its role in the response to vascular injury remain to be determined.

Characteristics of response of isolated smooth muscle cells to cholinergic drugs

1977 ◽  
Vol 232 (3) ◽  
pp. C144-C154 ◽  
Author(s):  
F. S. Fay ◽  
J. J. Singer
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Cholinergic Receptor ◽  
Lower Sensitivity ◽  
Isolated Cells ◽  
Contractile Responses ◽  
Intact Tissue ◽  
Isolated Smooth Muscle Cells ◽  
Higher Sensitivity

The contractile responses of suspensions of isolated smooth muscle cells from the stomach muscularis of Bufo marinus were assessed with a Coulter counter. Contractile responses of strips from the same tissue were recorded isotonically. Suspensions of isolated smooth muscle cells exhibit a dose-dependent graded response to cholinergic agonists. The intact tissue has a lower sensitivity than the isolated cells to acetycholine but a higher sensitivity to carbachol. The higher sensitivity of isolated cells to acetycholine probably reflected decreased efficiency of cholinesterases upon removal of diffusion barriers. Because the isolated smooth muscle cells have affinity constants for atropine (K1 equals 0.07 +/- 0.02NM) and carbachol (9.5 +/- 3.7 muM) similar to that in this and other intact tissues, the affinity of the cholinergic receptor appears unaffected by cell isolation. The rate constant for dissociation (k2) of atropine was estimated from the slowing of response to carbachol by atropine; k2 in the isolated cells is 100 times larger than seen in intact tissues. Further insight into the interaction of cholinergic substances with their smooth muscle receptors might by obtained using this system. The isolated cells contain intact receptors, and diffusion limitations inherent to intact tissue have been removed.

Mechanisms of mechanical strain memory in airway smooth muscle

2005 ◽  
Vol 83 (10) ◽  
pp. 811-815 ◽  
Author(s):  
Hak Rim Kim ◽  
Chi-Ming Hai
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Mechanical Performance ◽  
Mechanical Strain ◽  
Muscle Cells ◽  
Cholinergic Receptor ◽  
Airway Smooth Muscle Cells ◽  
Deep Inspiration ◽  
Initial Length

We evaluated the hypothesis that mechanical deformation of airway smooth muscle induces structural remodeling of airway smooth muscle cells, thereby modulating mechanical performance in subsequent contractions. This hypothesis implied that past experience of mechanical deformation was retained (or "memorized") as structural changes in airway smooth muscle cells, which modulated the cell's subsequent contractile responses. We termed this phenomenon mechanical strain memory. Preshortening has been found to induce attenuation of both force and isotonic shortening velocity in cholinergic receptor-activated airway smooth muscle. Rapid stretching of cholinergic receptor-activated airway smooth muscle from an initial length to a final length resulted in post-stretch force and myosin light chain phosphorylation that correlated significantly with initial length. Thus post-stretch muscle strips appeared to retain memory of the initial length prior to rapid stretch (mechanical strain memory). Cytoskeletal recruitment of actin- and integrin- binding proteins and Erk 1/2 MAPK appeared to be important mechanisms of mechanical strain memory. Sinusoidal length oscillation led to force attenuation during oscillation and in subsequent contractions in intact airway smooth muscle, and p38 MAPK appeared to be an important mechanism. In contrast, application of local mechanical strain to cultured airway smooth muscle cells induced local actin polymerization and cytoskeletal stiffening. It is conceivable that deep inspiration-induced bronchoprotection may be a manifestation of mechanical strain memory such that mechan ical deformation from past breathing cycles modulated the mechanical performance of airway smooth muscle in subsequent cycles in a continuous and dynamic manner.Key words: airway, cytoskeleton, deep inspiration, mechanics, smooth muscle.

scholarly journals TMEM16A channel upregulation in arterial smooth muscle cells produces vasoconstriction during diabetes

2021 ◽  
Author(s):  
M. Dennis Leo ◽  
Dieniffer Peixoto-Neves ◽  
Wen Yin ◽  
Somasundaram Raghavan ◽  
Padmapriya Muralidharan ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Current Density ◽  
Vascular Dysfunction ◽  
Muscle Cells ◽  
Cell Types ◽  
Myogenic Tone ◽  
Arterial Smooth Muscle ◽  
Functional Consequences ◽  
Arterial Smooth Muscle Cells

The pathological involvement of anion channels in vascular dysfunction that occurs during type 2 diabetes (T2D) is unclear. Here, we tested the hypothesis that TMEM16A, a calcium-activated chloride (Cl-) channel, contributes to modifications in arterial contractility during T2D. Our data indicate that T2D increased TMEM16A mRNA in arterial smooth muscle cells and total and surface TMEM16A protein in resistance-size cerebral and hindlimb arteries of mice. To examine vascular cell types in which TMEM16A protein increased and the functional consequences of TMEM16A upregulation during T2D, we generated tamoxifen-inducible, smooth muscle-specific TMEM16A knockout (TMEM16A smKO) mice. T2D increased both TMEM16A protein and Cl- current density in arterial smooth muscle cells of control (TMEM16Afl/fl) mice. In contrast, T2D did not alter arterial TMEM16A protein or Cl- current density in smooth muscle cells of TMEM16A smKO mice. Intravascular pressure stimulated greater vasoconstriction (myogenic tone) in arteries of T2D TMEM16Afl/fl mice than in arteries of non-diabetic TMEM16Afl/fl mice. This elevation in myogenic tone in response to T2D was abolished in arteries of T2D TMEM16A smKO mice. T2D also reduced Akt2 protein and activity in arteries of T2D mice. siRNA-mediated knockdown of Akt2, but not Akt1, increased arterial TMEM16A protein in non-diabetic mice. In summary, data indicate that T2D is associated with an increase in TMEM16A expression and currents in arterial smooth muscle cells that produces vasoconstriction. Data also suggest that a reduction in Akt2 function drives these pathological alterations during T2D.

Ultrastructure of myoepithelial cell in parotid gland

1988 ◽  
Vol 46 ◽  
pp. 342-343
Author(s):  
C. N. Sun
Keyword(s):  
Parotid Gland ◽  
Osmium Tetroxide ◽  
Individual Cell ◽  
Branching Processes ◽  
Muscle Cells ◽  
Myoepithelial Cells ◽  
Uranyl Acetate ◽  
Thin Sections ◽  
Gland Carcinoma ◽  
Parotid Gland Carcinoma

Myoepithelial cells have been observed in the prostate, harderian, apocrine, exocrine sweat and mammary glands. Such cells and their numerous branching processes form basket-like structures around the glandular acini. Their shapes are quite different from structures seen either in spindleshaped smooth muscle cells or skeletal muscle cells. These myoepithelial cells lie on the epithelial side of the basement membrane in the glands. This presentation describes the ultrastructure of such myoepithelial cells which have been found also in the parotid gland carcinoma from a 45-year old patient.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4 percent glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1 percent buffered osmium tetroxide for 1 hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate. Ultrastructurally, the pattern of each individual cell showed wide variations.

Immunogold localization of HMB-45 antigen in pulmonary lymphangiomyomatosis

1995 ◽  
Vol 53 ◽  
pp. 998-999
Author(s):  
J.M. Minda ◽  
E. Dessy ◽  
G. G. Pietra
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Muscle Cells ◽  
Ultrastructural Localization ◽  
Reproductive Age ◽  
Thin Sections ◽  
Smooth Muscle Proliferation ◽  
Hmb 45

Pulmonary lymphangiomyomatosis (PLAM) is a rare disease occurring exclusively in women of reproductive age. It involves the lungs, lymph nodes and lymphatic ducts. In the lungs, it is characterized by the proliferation of smooth muscle cells around lymphatics in the bronchovascular bundles, lobular septa and pleura The nature of smooth muscle proliferation in PLAM is still unclear. Recently, reactivity of the smooth muscle cells for HMB-45, a melanoma-related antigen has been reported by immunohistochemistry. The purpose of this study was the ultrastructural localization of HMB-45 immunoreactivity in these cells using gold-labeled antibodies.Lung tissue from three cases of PLAM, referred to our Institution for lung transplantation, was embedded in either Poly/Bed 812 post-fixed in 1% osmium tetroxide, or in LR White, without osmication. For the immunogold technique, thin sections were placed on Nickel grids and incubated with affinity purified, monoclonal anti-melanoma antibody HMB-45 (1:1) (Enzo Diag. Co) overnight at 4°C. After extensive washing with PBS, grids were treated with Goat-anti-mouse-IgG-Gold (5nm) (1:10) (Amersham Life Sci) for 1 hour, at room temperature.

Macroorganisation and flexibility of thylakoid membranes

2019 ◽  
Vol 476 (20) ◽  
pp. 2981-3018 ◽  
Author(s):  
Petar H. Lambrev ◽  
Parveen Akhtar
Keyword(s):  
Light Harvesting ◽  
Current Knowledge ◽  
Three Dimensional ◽  
Photosynthetic Apparatus ◽  
Dynamic Responses ◽  
State Transitions ◽  
Photochemical Quenching ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Light Harvesting Complex Ii

Abstract The light reactions of photosynthesis are hosted and regulated by the chloroplast thylakoid membrane (TM) — the central structural component of the photosynthetic apparatus of plants and algae. The two-dimensional and three-dimensional arrangement of the lipid–protein assemblies, aka macroorganisation, and its dynamic responses to the fluctuating physiological environment, aka flexibility, are the subject of this review. An emphasis is given on the information obtainable by spectroscopic approaches, especially circular dichroism (CD). We briefly summarise the current knowledge of the composition and three-dimensional architecture of the granal TMs in plants and the supramolecular organisation of Photosystem II and light-harvesting complex II therein. We next acquaint the non-specialist reader with the fundamentals of CD spectroscopy, recent advances such as anisotropic CD, and applications for studying the structure and macroorganisation of photosynthetic complexes and membranes. Special attention is given to the structural and functional flexibility of light-harvesting complex II in vitro as revealed by CD and fluorescence spectroscopy. We give an account of the dynamic changes in membrane macroorganisation associated with the light-adaptation of the photosynthetic apparatus and the regulation of the excitation energy flow by state transitions and non-photochemical quenching.

Sign in / Sign up

Export Citation Format

Share Document