A specific sugar transport mechanism in smooth muscle and its regulation

1976 ◽  
Vol 54 (3) ◽  
pp. 254-261 ◽  
Author(s):  
I. Bihler ◽  
P. C. Sawh ◽  
J. Elbrink
Keyword(s):  
Smooth Muscle ◽  
Sugar Transport ◽  
Facilitated Diffusion ◽  
Inhibitory Effects ◽  
Rat Urinary Bladder ◽  
Specificity And Sensitivity ◽  
Rate Limiting ◽  
Specific Sugar

The membrane transport of 3-O-methyl-D-glucose was studied in vitro in a smooth muscle, the detrusor of rat urinary bladder. Transport occurred by facilitated diffusion and showed the same chemical specificity and sensitivity to specific inhibitors as skeletal and cardiac muscle but its insulin sensitivity was smaller. Transport was increased by agents inhibiting the Na+ pump and was decreased by agents which increased Na+ and K+ gradients by apparently stimulating the Na+ pump. In accord with a rate limiting role of transport in glucose utilization, similar stimulating and inhibitory effects were seen when CO2 production from [14C]glucose was measured.

Differential effects of prostaglandin E2 on contractions of airway smooth muscle

1989 ◽  
Vol 66 (3) ◽  
pp. 1397-1407 ◽  
Author(s):  
J. M. Madison ◽  
C. A. Jones ◽  
R. M. Sankary ◽  
J. K. Brown
Keyword(s):  
Smooth Muscle ◽  
Adenylate Cyclase ◽  
Prostaglandin E2 ◽  
Cyclase Activity ◽  
Adenylate Cyclase Activity ◽  
Tracheal Smooth Muscle ◽  
Inhibitory Effects ◽  
Camp Content

In an in vitro muscle bath, the active tension generated by strips of canine tracheal smooth muscle responding to cumulative additions of either histamine (10(-8) to 10(-3) M) or acetylcholine (10(-9) to 10(-3) M) was measured in the absence and presence of prostaglandin E2 (PGE2) (10(-6) to 10(-5) M). When contractile responses of equal magnitude were compared, the contractions elicited by acetylcholine were resistant to the inhibitory effects of PGE2, relative to comparable contractions elicited by histamine. To assess the role of adenylate cyclase in determining the different responses to histamine and acetylcholine in the presence of PGE2, we assayed adenylate cyclase activity in membranes prepared from canine tracheal smooth muscle and found that acetylcholine, but not histamine, decreased PGE2-stimulated adenylate cyclase activity by 48 +/- 2% (mean +/- SE; n = 5). However, in other experiments, we found that even large pharmacological increases in tissue adenosine 3′,5′-cyclic monophosphate (cAMP) content only partially inhibited muscarinic tone. Also, exogenously applied analogues of cyclic AMP inhibited contractions induced by histamine more effectively than comparable contractions induced by acetylcholine. We concluded that acetylcholine decreased adenylate cyclase activity in membranes prepared from canine tracheal smooth muscle and that this effect may have contributed to, but did not completely account for, the relative resistance of muscarinic contractions to the inhibitory effects of PGE2.

Facilitated diffusion of monosaccharides in smooth muscle of rat vas deferens in vitro

1984 ◽  
Vol 62 (9) ◽  
pp. 1112-1115 ◽  
Author(s):  
J. Elbrink
Keyword(s):  
Smooth Muscle ◽  
Vas Deferens ◽  
Contractile Activity ◽  
Sugar Transport ◽  
Insulin Receptors ◽  
Rat Vas Deferens ◽  
Diffusion System ◽  
Facilitated Diffusion ◽  
High Concentration

The suitability of rat vas deferens for investigating sugar transport in smooth muscle was determined in vitro, with the nonmetabolized glucose analog 3-O-methyl-D-glucose as test sugar. Vas deferens smooth muscle contains a facilitated diffusion system for monosaccharides, as shown by saturation of the transport sites and by competition between 3-O-methyl-D-glucose and D-glucose. The activity of the facilitated diffusion system could be enhanced by hyperosmolarity and by contractile activity, but frequency dependency could not be established. A high concentration of insulin (100 mU/mL) was required to stimulate sugar transport. As smooth muscle is not a primary tissue for the storage of energy reserves, it does not require large numbers of insulin receptors.

scholarly journals Sugar Transport through Maltoporin of Escherichia coli: Role of the Greasy Slide

2002 ◽  
Vol 184 (11) ◽  
pp. 2994-2999 ◽  
Author(s):  
Patrick Van Gelder ◽  
Fabrice Dumas ◽  
Ingrid Bartoldus ◽  
Nathalie Saint ◽  
Alexei Prilipov ◽  
...  
Keyword(s):  
Noise Analysis ◽  
Sugar Transport ◽  
Crystallographic Analysis ◽  
Facilitated Diffusion ◽  
Alanine Scanning Mutagenesis ◽  
Sugar Addition ◽  
Channel Constriction

ABSTRACT The lining of the maltodextrin-specific maltoporin (LamB) channel exhibits a string of aromatic residues, the greasy slide, part of which has been shown previously by crystallography to be involved in substrate binding. To probe the functional role of the greasy slide, alanine scanning mutagenesis has been performed on the six greasy slide residues and Y118 at the channel constriction. The mutants were characterized by an in vivo uptake assay and sugar-induced-current-noise analysis. Crystallographic analysis of the W74A mutant showed no perturbation of the structure. All mutants showed considerably decreased maltose uptake rates in vivo (<10% of the wild-type value), indicating the functional importance of the investigated residues. Substitutions at the channel center revealed appreciably increased (up to 100-fold) in vitro half-saturation concentrations for maltotriose and maltohexaose binding to the channel. Sugar association rates, however, were significantly affected also by the mutations at either end of the slide (W74A, W358A, and F227A), an effect which became most apparent upon nonsymmetrical sugar addition. The kinetic data are discussed on the basis of an asymmetric one-site two-barrier model, which suggests that, at low substrate concentrations, as are found under physiological conditions, only the heights of the extracellular and periplasmic barriers, which are reduced by the presence of the greasy slide, determine the efficiency of this facilitated diffusion channel.

Antagonists of EDRF attenuate acetylcholine-induced vasodilation in isolated hamster lungs

1992 ◽  
Vol 72 (6) ◽  
pp. 2162-2167 ◽  
Author(s):  
C. M. Tseng ◽  
W. Mitzner
Keyword(s):  
Methylene Blue ◽  
Smooth Muscle ◽  
Angiotensin Ii ◽  
Krebs Solution ◽  
Inhibitory Effects ◽  
Relaxing Factor ◽  
Prostaglandin F2 Alpha ◽  
Pressor Responses

To evaluate the role of endothelium-dependent relaxing factor (EDRF) in acetylcholine- (ACh) induced vasodilation in the intact pulmonary circulation, we examined the effects of atropine and three EDRF antagonists that have been shown to be effective in vitro: nitro-L-arginine (NOARG), hemoglobin (Hb), and methylene blue (MB). We studied ACh-induced dilation after preconstriction with angiotensin II and prostaglandin F2 alpha (PGF2 alpha) in hamster lungs perfused with Krebs solution containing Ficoll (4 g/dl) and indomethacin (10 microM). In the constricted lungs with no blockers, infusion of ACh (1 microM) decreased the constriction by 67%, and this effect was completely abolished by atropine pretreatment (1 microM). Treatment of hamster lungs with each of the three EDRF blockers, NOARG (30 microM), Hb (10 microM), and MB (250 microM), augmented the pressor responses to angiotensin II and PGF2 alpha. However, NOARG and MB inhibited the ACh-induced dilation by 49 and 60%, respectively, without affecting vasodilatory responses to isoproterenol, an agent that relaxes vascular smooth muscle independent of EDRF synthesis. In contrast, Hb significantly inhibited both ACh- and isoproterenol-induced vasodilations. Because all these EDRF antagonists attenuated ACh-induced vasodilation in intact hamster lungs, we conclude that EDRF plays a role in this response. Nonselective inhibitory effects of Hb in hamster lungs, however, suggest that mechanisms other than inhibition of EDRF by this agent are also involved.

scholarly journals Amphetamine-Decreased Progesterone and Estradiol Release in Rat Granulosa Cells: The Regulatory Role of cAMP- and Ca2+-Mediated Signaling Pathways

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 493
Author(s):  
 Chung-Yu Chen ◽  
Chien-Rung Chen ◽  
Chiao-Nan Chen ◽  
Paulus S. Wang ◽  
Toby Mündel ◽  
...  
Keyword(s):  
Granulosa Cells ◽  
Prostaglandin F2α ◽  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Steroidogenic Enzyme ◽  
Estradiol Secretion ◽  
Basal Release ◽  
Ca2 Channels

The purpose of this study is to evaluate the amphetamine effects on progesterone and estradiol production in rat granulosa cells and the underlying cellular regulatory mechanisms. Freshly dispersed rat granulosa cells were cultured with various test drugs in the presence of amphetamine, and the estradiol/progesterone production and the cytosolic cAMP level were measured. Additionally, the cytosolic-free Ca2+ concentrations ([Ca2+]i) were measured to examine the role of Ca2+ influx in the presence of amphetamine. Amphetamine in vitro inhibited both basal and porcine follicle-stimulating hormone-stimulated estradiol/progesterone release, and amphetamine significantly decreased steroidogenic enzyme activities. Adding 8-Bromo-cAMP did not recover the inhibitory effects of amphetamine on progesterone and estradiol release. H89 significantly decreased progesterone and estradiol basal release but failed to enhance a further amphetamine inhibitory effect. Amphetamine was capable of further suppressing the release of estradiol release under the presence of nifedipine. Pretreatment with the amphetamine for 2 h decreased the basal [Ca2+]i and prostaglandin F2α-stimulated increase of [Ca2+]i. Amphetamine inhibits progesterone and estradiol secretion in rat granulosa cells through a mechanism involving decreased PKA-downstream steroidogenic enzyme activity and L-type Ca2+ channels. Our current findings show that it is necessary to study the possibility of amphetamine perturbing reproduction in females.

scholarly journals Aging-associated changes in microRNA expression profile of internal anal sphincter smooth muscle: Role of microRNA-133a

2016 ◽  
Vol 311 (5) ◽  
pp. G964-G973 ◽  
Author(s):  
Jagmohan Singh ◽  
Ettickan Boopathi ◽  
Sankar Addya ◽  
Benjamin Phillips ◽  
Isidore Rigoutsos ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Anal Sphincter ◽  
Internal Anal Sphincter ◽  
Smooth Muscles ◽  
Smooth Muscle Contractility ◽  
Network Analyses ◽  
Rhoa Signaling

A comprehensive genomic and proteomic, computational, and physiological approach was employed to examine the (previously unexplored) role of microRNAs (miRNAs) as regulators of internal anal sphincter (IAS) smooth muscle contractile phenotype and basal tone. miRNA profiling, genome-wide expression, validation, and network analyses were employed to assess changes in mRNA and miRNA expression in IAS smooth muscles from young vs. aging rats. Multiple miRNAs, including rno-miR-1, rno-miR-340-5p, rno-miR-185, rno-miR-199a-3p, rno-miR-200c, rno-miR-200b, rno-miR-31, rno-miR-133a, and rno-miR-206, were found to be upregulated in aging IAS. qPCR confirmed the upregulated expression of these miRNAs and downregulation of multiple, predicted targets ( Eln, Col3a1, Col1a1, Zeb2, Myocd, Srf, Smad1, Smad2, Rhoa/Rock2, Fn1, Tagln v2, Klf4, and Acta2) involved in regulation of smooth muscle contractility. Subsequent studies demonstrated an aging-associated increase in the expression of miR-133a, corresponding decreases in RhoA, ROCK2, MYOCD, SRF, and SM22α protein expression, RhoA-signaling, and a decrease in basal and agonist [U-46619 (thromboxane A2analog)]-induced increase in the IAS tone. Moreover, in vitro transfection of miR-133a caused a dose-dependent increase of IAS tone in strips, which was reversed by anti-miR-133a. Last, in vivo perianal injection of anti-miR-133a reversed the loss of IAS tone associated with age. This work establishes the important regulatory effect of miRNA-133a on basal and agonist-stimulated IAS tone. Moreover, reversal of age-associated loss of tone via anti-miR delivery strongly implicates miR dysregulation as a causal factor in the aging-associated decrease in IAS tone and suggests that miR-133a is a feasible therapeutic target in aging-associated rectoanal incontinence.

Heparan sulfate side chains have a critical role in the inhibitory effects of perlecan on vascular smooth muscle cell response to arterial injury

2014 ◽  
Vol 307 (3) ◽  
pp. H337-H345 ◽  
Author(s):  
Lara Gotha ◽  
Sang Yup Lim ◽  
Azriel B. Osherov ◽  
Rafael Wolff ◽  
Beiping Qiang ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Critical Role ◽  
Arterial Injury ◽  
Side Chains ◽  
Wild Type ◽  
Injury Response ◽  
Migratory Response

Perlecan is a proteoglycan composed of a 470-kDa core protein linked to three heparan sulfate (HS) glycosaminoglycan chains. The intact proteoglycan inhibits the smooth muscle cell (SMC) response to vascular injury. Hspg2Δ3/Δ3 (MΔ3/Δ3) mice produce a mutant perlecan lacking the HS side chains. The objective of this study was to determine differences between these two types of perlecan in modifying SMC activities to the arterial injury response, in order to define the specific role of the HS side chains. In vitro proliferative and migratory activities were compared in SMC isolated from MΔ3/Δ3 and wild-type mice. Proliferation of MΔ3/Δ3 SMC was 1.5× greater than in wild type ( P < 0.001), increased by addition of growth factors, and showed a 42% greater migratory response than wild-type cells to PDGF-BB ( P < 0.001). In MΔ3/Δ3 SMC adhesion to fibronectin, and collagen types I and IV was significantly greater than wild type. Addition of DRL-12582, an inducer of perlecan expression, decreased proliferation and migratory response to PDGF-BB stimulation in wild-type SMC compared with MΔ3/Δ3. In an in vivo carotid artery wire injury model, the medial thickness, medial area/lumen ratio, and macrophage infiltration were significantly increased in the MΔ3/Δ3 mice, indicating a prominent role of the HS side chain in limiting vascular injury response. Mutant perlecan that lacks HS side chains had a marked reduction in the inhibition of in vitro SMC function and the in vivo arterial response to injury, indicating the critical role of HS side chains in perlecan function in the vessel wall.

Abstract WMP31: Dedifferentiation of Smooth Muscle Cells and its Potential Contribution to Pathogenesis of Intracranial Aneurysms

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Mieko Oka ◽  
Nobuhiko Ohno ◽  
Takakazu Kawamata ◽  
Tomohiro Aoki
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Inflammatory Responses ◽  
Muscle Cells ◽  
Inflammatory Factors ◽  
Potential Contribution ◽  
Electron Microscopic

Introduction: Intracranial aneurysm (IA) affects 1 to 5 % in general public and becomes the primary cause of subarachnoid hemorrhage, the most severe form of stroke. However, currently, no drug therapy is available for IAs to prevent progression and rupture of lesions. Elucidation of mechanisms underlying the disease is thus mandatory. Considering the important role of vascular smooth muscle cells (SMCs) in the maintenance of stiffness of arterial walls and also in the pathogenesis of atherosclerosis via mediating inflammatory responses, we in the present study analyzed morphological or phenotypical changes of SMCs during the disease development in the lesions. Methods: We subjected rats to an IA model in which lesions are induced by increase of hemodynamic force loading on intracranial arterial bifurcations and performed histopathological analyses of induced lesions including the electron microscopic examination. We then immunostained specimens from induced lesions to explore factors responsible for dedifferentiation or migration of SMCs. In vitro study was also done to examine effect of some candidate factors on dedifferentiation or migration of cultured SMCs. Results: We first found the accumulation of SMCs underneath the endothelial cell layer mainly at the neck portion of the lesion. These cells was positive for the embryonic form of myosin heavy chain, a marker for the dedifferentiated SMCs, and the expression of pro-inflammatory factors like TNF-α. In immunostaining to explore the potential factor regulating the dedifferentiation of SMCs, we found that Platelet-derived growth factor-BB (PDGF-BB) was expressed in endothelial cells at the neck portion of IA walls. Consistently, recombinant PDGF-BB could promote the dedifferentiate of SMCs and chemo-attracted them in in vitro. Finally, in the stenosis model of the carotid artery, PDGF-BB expression was induced in endothelial cells in which high wall shear stress was loaded and the dedifferentiation of SMCs occurred there. Conclusions: The findings from the present study imply the role of dedifferentiated SMCs partially recruited by PDGF-BB from endothelial cells in the formation of inflammatory microenvironment at the neck portion of IA walls, leading to the progression of the disease.

Abstract 13598: The G-protein BetaGamma Subunits Regulate Platelet Function

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Ahmed Alarabi ◽  
Zubair Karim ◽  
Victoria Hinojos ◽  
Patricia A Lozano ◽  
Keziah Hernandez ◽  
...  
Keyword(s):  
G Protein ◽  
Platelet Function ◽  
Thrombus Formation ◽  
Human Platelets ◽  
Inhibitory Effects ◽  
Clot Retraction ◽  
Betagamma Subunits

Platelet activation involves tightly regulated processes to ensure a proper hemostasis response, but when unbalanced, can lead to pathological consequences such as thrombus formation. G-protein coupled receptors (GPCRs) regulate platelet function by interacting with and mediating the response to various physiological agonists. To this end, an essential mediator of GPCR signaling is the G protein Gαβγ heterotrimers, in which the βγ subunits are central players in downstream signaling pathways. While much is known regarding the role of the Gα subunit in platelet function, that of the βγ remains poorly understood. Therefore, we investigated the role of Gβγ subunits in platelet function using a Gβγ (small molecule) inhibitor, namely gallein. We observed that gallein inhibits platelet aggregation and secretion in response to agonist stimulation, in both mouse and human platelets. Furthermore, gallein also exerted inhibitory effects on integrin αIIbβ3 activation and clot retraction. Finally, gallein’s inhibitory effects manifested in vivo , as documented by its ability to modulate physiological hemostasis and delay thrombus formation. Taken together, our findings demonstrate, for the first time, that Gβγ directly regulates GPCR-dependent platelet function, in vitro and in vivo . Moreover, these data highlight Gβγ as a novel therapeutic target for managing thrombotic disorders.

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