Inhibitory Effect of β3-Adrenoceptor Agonist in Lower Esophageal Sphincter Smooth Muscle: In Vitro Studies

2003 ◽  
Vol 304 (1) ◽  
pp. 48-55 ◽  
Author(s):  
D. N. K. Sarma ◽  
Kuldip Banwait ◽  
Ashim Basak ◽  
Anthony J. DiMarino ◽  
Satish Rattan
Keyword(s):  
Smooth Muscle ◽  
Lower Esophageal Sphincter ◽  
Inhibitory Effect ◽  
In Vitro Studies ◽  
Adrenoceptor Agonist ◽  
Esophageal Sphincter

scholarly journals Contractile and Endothelium-Dependent Dilatory Responses of Cerebral Arteries at Various Extracellular Magnesium Concentrations

1991 ◽  
Vol 11 (1) ◽  
pp. 161-164 ◽  
Author(s):  
Mária Faragó ◽  
Csaba Szabó ◽  
Eörs Dóra ◽  
Ildikó Horváth ◽  
Arisztid G. B. Kovách
Keyword(s):  
Smooth Muscle ◽  
Vascular Reactivity ◽  
Calcium Influx ◽  
Cerebral Arteries ◽  
Inhibitory Effect ◽  
Contractile Responses ◽  
Middle Cerebral Arteries ◽  
The Right ◽  
Endothelial Receptor

To clarify the effect of extracellular magnesium (Mg2+) on the vascular reactivity of feline isolated middle cerebral arteries, the effects of slight alterations in the Mg2+ concentration on the contractile and endothelium-dependent dilatory responses were investigated in vitro. The contractions, induced by 10−8-10−5 M norepinephrine, were significantly potentiated at low Mg2+ (0.8 m M v. the normal, 1.2 m M). High (1.6 and 2.0 m M) Mg2+ exhibited an inhibitory effect on the contractile responses. No significant changes, however, in the EC50 values for norepinephrine were found. The endothelium-dependent relaxations induced by 108–10−5 M acetylcholine were inhibited by high (1.6 and 2.0 m M) Mg2+. Lowering of the Mg2+ concentration to 0.8 m M or total withdrawal of this ion from the medium failed to alter the dilatory potency of acetylcholine. The changes in the dilatory responses also shifted the EC50 values for acetylcholine to the right. The present results show that the contractile responses of the cerebral arteries are extremely susceptible to the changes of Mg2+ concentrations. In response to contractile and endothelium-dependent dilatory agonists, Mg2+ probably affects both the calcium influx into the endothelial and smooth muscle cells as well as the binding of acetylcholine to its endothelial receptor. Since Mg2+ deficiency might facilitate the contractile but not the endothelium-dependent relaxant responses, the present study supports a role for Mg2+ deficiency in the development of the cerebral vasospasm.

Abolition by Myosin and Heavy Meromyosin of the Inhibitory Effect of Smooth-Muscle Actomyosin Antibodies on Cell Aggregation In Vitro

1973 ◽  
Vol 12 (2) ◽  
pp. 631-639
Author(s):  
R. B. KEMP ◽  
B. M. JONES ◽  
U. GRÖSCHEL-STEWART
Keyword(s):  
Smooth Muscle ◽  
Striated Muscle ◽  
Cell Aggregation ◽  
Inhibitory Effect ◽  
Regulatory Function ◽  
Rabbit Serum ◽  
Heavy Meromyosin ◽  
Γ Globulins ◽  
Dissociated Cells

The ability of anti-chicken smooth-muscle actomyosin γ-globulins (anti-GAM) to inhibit the aggregation of dissociated cells from the skeletal muscle and liver of chick embryos was abolished by pretreatment of the anti-GAM with either myosin or heavy meromyosin (HMM). When the same cells were treated with HMM at a concentration of 1 mg per 2 x 106 cells/ml Eagle's MEM they aggregated as readily as untreated cells. The negative electrophoretic mobility of the embryonic chick fibroblastic cells was significantly reduced by the globulin fraction of anti-GAM but not of HMM-treated anti-GAM or non-immunized rabbit serum. Anti-chicken striated muscle actomyosin γ-globulins slightly reduced negative mobility but HMM had no effect. The experiments show that the inhibitory effect on cell aggregation of anti-GAM preparations is produced by the anti-myosin antibodies. They also provide support for the theory that a surface-localized myosin-like protein has a regulatory function in cell adhesion.

scholarly journals The Strain on Airway Smooth Muscle During a Deep Inspiration to Total Lung Capacity

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Ynuk Bossé
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Total Lung Capacity ◽  
In Vitro Studies ◽  
Deep Inspiration ◽  
Bronchodilator Effect ◽  
Lung Capacity ◽  
Residual Capacity

The deep inspiration (DI) maneuver entices a great deal of interest because of its ability to temporarily ease the flow of air into the lungs. This salutary effect of a DI is proposed to be mediated, at least partially, by momentarily increasing the operating length of airway smooth muscle (ASM). Concerningly, this premise is largely derived from a growing body of in vitro studies investigating the effect of stretching ASM by different magnitudes on its contractility. The relevance of these in vitro findings remains uncertain, as the real range of strains ASM undergoes in vivo during a DI is somewhat elusive. In order to understand the regulation of ASM contractility by a DI and to infer on its putative contribution to the bronchodilator effect of a DI, it is imperative that in vitro studies incorporate levels of strains that are physiologically relevant. This review summarizes the methods that may be used in vivo in humans to estimate the strain experienced by ASM during a DI from functional residual capacity (FRC) to total lung capacity (TLC). The strengths and limitations of each method, as well as the potential confounders, are also discussed. A rough estimated range of ASM strains is provided for the purpose of guiding future in vitro studies that aim at quantifying the regulatory effect of DI on ASM contractility. However, it is emphasized that, owing to the many limitations and confounders, more studies will be needed to reach conclusive statements.

Role of endothelial cells in regulating hemoglobin-induced changes in lymphatic pumping

1992 ◽  
Vol 263 (6) ◽  
pp. H1880-H1887 ◽  
Author(s):  
R. M. Elias ◽  
J. Eisenhoffer ◽  
M. G. Johnston
Keyword(s):  
Endothelial Cells ◽  
Smooth Muscle ◽  
Inhibitory Effect ◽  
Direct Inhibitory Effect ◽  
Induced Changes ◽  
Lymphatic Pumping ◽  
Pumping Activity

Studies with a sheep isolated duct preparation in vivo demonstrated that the route of administration of hemoglobin was important in demonstrating its inhibitory effect on lymphatic pumping. With autologous oxyhemoglobin administered intravenously (final plasma concentration 5 x 10(-5) M), pumping was not inhibited. However, the addition of oxyhemoglobin (5 x 10(-5) M) into the reservoir (lumen of the duct) resulted in > 95% inhibition of pumping. The extraluminal administration of oxyhemoglobin (10(-5) M) to bovine mesenteric lymphatics in vitro resulted in a 40% inhibition of pumping, whereas the introduction of oxyhemoglobin (10(-5) M) into the lumen of the vessels suppressed pumping 95%. In vessels mechanically denuded of endothelium, intraluminal oxyhemoglobin inhibited pumping 50%. These results suggested that oxyhemoglobin depressed pumping through an effect on both smooth muscle and endothelium. Once pumping was inhibited with oxyhemoglobin administration, stimulation of the duct with elevations in transmural pressure restored pumping activity when endothelial cells were present. However, in the absence of endothelium, pumping decreased with increases in distending pressures. We conclude that oxyhemoglobin has a direct inhibitory effect on lymphatic smooth muscle. The ability of oxyhemoglobin to alter the pressure range over which the lymph pump operates appears to be dependent on an intact endothelium.

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