scholarly journals Effect of Imperatorin on the Spontaneous Motor Activity of Rat Isolated Jejunum Strips

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Marta Mendel ◽  
Krystyna Skalicka-Woźniak ◽  
Magdalena Chłopecka ◽  
Natalia Dziekan
Keyword(s):  
Smooth Muscle ◽  
Motor Activity ◽  
High Performance ◽  
Soluble Guanylate Cyclase ◽  
Potassium Concentration ◽  
Underlying Mechanism ◽  
High Potassium ◽  
Pharmacological Studies ◽  
Influx Pathways ◽  
High Potassium Concentration

Imperatorin, a psoralen-type furanocoumarin, is a potent myorelaxant agent acting as a calcium antagonist on vascular smooth muscle. Its effects on other types of smooth muscle remain unknown. Therefore, the aim of this study was to investigate the hypothesized myorelaxant effect of imperatorin on gut motor activity and, possibly, to define the underlying mechanism of action. Imperatorin was made available for pharmacological studies from the fruits of the widely availableAngelica officinalisthrough the application of high-performance countercurrent chromatography (HPCCC). Imperatorin generated reversible relaxation of jejunum strips dose-dependently (1–100 μM). At 25 and 50 μM, imperatorin caused relaxation comparable to the strength of the reaction induced by isoproterenol (Isop) at 0.1 μM. The observed response resulted neither from the activation of soluble guanylate cyclase, nor fromβ-adrenoreceptor involvement, nor from Ca2+-activated potassium channels. Imperatorin relaxed intestine strips precontracted with high potassium concentration, attenuated the force and duration of K+-induced contractions, and modulated the response of jejunum strips to acetylcholine. The results suggest that imperatorin probably interacts with various Ca2+influx pathways in intestine smooth muscle. The types of some calcium channels involved in the activity of imperatorin will be examined in a subsequent study.

Movement of Aldolase From Excised Rat Diaphragm

1956 ◽  
Vol 185 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Kenneth L. Zierler
Keyword(s):  
Aqueous Solution ◽  
Cell Membrane ◽  
Potassium Concentration ◽  
Fiber Surface ◽  
Rat Diaphragm ◽  
High Potassium ◽  
Flow Through ◽  
High Potassium Concentration

A protein, aldolase, flows from excised rat diaphragm incubated in a variety of media. The rate of outflow of aldolase is increased by anoxia and by a high potassium concentration in the medium, and it is decreased by a reduction in temperature and by addition of glucose. When diaphragm is transferred to fresh media and reincubated the rate of outflow of aldolase is also accelerated. From measurements of rates of outflow of aldolase, estimates have been made of the area of the membrane required for aldolase to flow through the cell membrane as though it were flowing simply through an aqueous solution. This area is about 10–7–10–8 of the estimated total fiber surface. The estimated area for diffusion of aldolase is modified 16-fold by factors which alter the metabolism of diaphragm.

Protection of atrial function in hypoxia by high potassium concentration

1994 ◽  
Vol 25 (3) ◽  
pp. 401-407 ◽  
Author(s):  
Guglielmina Froldi ◽  
Luisa Pandolfo ◽  
Alessandro Chinellato ◽  
Eugenio Ragazzi ◽  
Laura Caparrotta ◽  
...  
Keyword(s):  
Potassium Concentration ◽  
Atrial Function ◽  
High Potassium ◽  
High Potassium Concentration

scholarly journals INFLUENCE OF EXTERNAL POTASSIUM ON THE SYNTHESIS AND DEPOSITION OF MATRIX COMPONENTS BY CHONDROCYTES IN VITRO

1974 ◽  
Vol 63 (3) ◽  
pp. 843-854 ◽  
Author(s):  
Jon C. Daniel ◽  
Robert A. Kosher ◽  
James E. Hamos ◽  
James W. Lash
Keyword(s):  
Culture Medium ◽  
Hyaline Cartilage ◽  
Cell Layer ◽  
Potassium Concentration ◽  
Cartilage Matrix ◽  
High Potassium ◽  
External Potassium ◽  
Matrix Components ◽  
High Potassium Concentration

The effect of a high external potassium concentration on the synthesis and deposition of matrix components by chondrocytes in cell culture was determined. There is a twofold increase in the amount of chondroitin 4- and 6-sulfate accumulated by chondrocytes grown in medium containing a high potassium concentration. There is also a comparable increase in the production of other sulfated glycosaminoglycans (GAG) including heparan sulfate and uncharacterized glycoprotein components. The twofold greater accumulation of GAG in the high potassium medium is primarily the result of a decrease in their rate of degradation. In spite of this increased accumulation of GAG, the cells in high potassium fail to elaborate appreciable quantities of visible matrix, although they do retain the typical chondrocytic polygonal morphology. Although most of the products are secreted into the culture medium in the high potassium environment, the cell layer retains the same amount of glycosaminoglycan as the control cultures. The inability of chondrocytes grown in high potassium to elaborate the typical hyaline cartilage matrix is not a consequence of an impairment in collagen synthesis, since there is no difference in the total amount of collagen synthesized by high potassium or control cultures. There is, however, a slight increase in the proportion of collagen that is secreted into the medium by chondrocytes in high potassium. Synthesis of the predominant cartilage matrix molecules is not sufficient in itself to ensure that these molecules will be assembled into a hyaline matrix.

scholarly journals Rapid adaptation to elevated extracellular potassium in the pyloric circuit of the crab, Cancer borealis

2020 ◽  
Vol 123 (5) ◽  
pp. 2075-2089 ◽  
Author(s):  
Lily S. He ◽  
Mara C.P. Rue ◽  
Ekaterina O. Morozova ◽  
Daniel J. Powell ◽  
Eric J. James ◽  
...  
Keyword(s):  
Potassium Concentration ◽  
Fold Increase ◽  
Stomatogastric Ganglion ◽  
Extracellular Potassium ◽  
Rapid Adaptation ◽  
Cancer Borealis ◽  
High Potassium ◽  
Transient Loss ◽  
High Potassium Concentration ◽  
Nonstationary Effects

Solutions with elevated extracellular potassium are commonly used as a depolarizing stimulus. We studied the effects of high potassium concentration ([K+]) on the pyloric circuit of the crab stomatogastric ganglion. A 2.5-fold increase in extracellular [K+] caused a transient loss of activity that was not due to depolarization block, followed by a rapid increase in excitability and recovery of spiking within minutes. This suggests that changing extracellular potassium can have complex and nonstationary effects on neuronal circuits.

Effect of Adrenergic Drugs on the Lantern of the Larval PHOTURIS FIREFLY

1968 ◽  
Vol 48 (2) ◽  
pp. 381-387
Author(s):  
ALBERT D. CALRLSON
Keyword(s):  
Potassium Concentration ◽  
Choline Chloride ◽  
High Potassium ◽  
Adrenergic Drugs ◽  
Significant Difference ◽  
Receptor Interactions ◽  
Intense Luminescence ◽  
Drug Receptor ◽  
High Potassium Concentration ◽  
Sodium And Potassium

1. A number of adrenergic drugs were tested for their ability to induce luminescence in the extirpated lantern of the firefly larva. The drugs produce sigmoid doseresponse curves characteristic of drug-receptor interactions when drug concentration is plotted against either maximum intensity or maximum rate of intensity rise. 2. Amphetamine and saline of high potassium concentration induce intense luminescence in freshly extirpated lanterns but act only weakly or not at all in lanterns suffering from treatment by reserpine injection 48 hr. previously. 3. No significant difference in response to norepinephrine was observed in lanterns immersed in standard saline, 0.32 M sucrose, 0.16 M choline chloride or 0.16 M-NaCl2 but 0.107 M-CaCl2 considerably slowed the response. 4. Some generalizations concerning structural character and effectiveness in inducing luminescence were made by comparing the drugs tested. It was not possible to describe the mode of action of the drugs. The observation, however, that solutions lacking sodium and potassium did not significantly alter the response was felt to argue against the action of the adrenergic drugs in affecting ion movement across the photocyte membrane.

Increase of membrane conductance by adrenaline in the smooth muscle of guinea-pig taenia coli

1969 ◽  
Vol 172 (1027) ◽  
pp. 89-102 ◽  
Keyword(s):  
Smooth Muscle ◽  
Potassium Concentration ◽  
Potassium Conductance ◽  
Membrane Conductance ◽  
Membrane Resistance ◽  
Taenia Coli ◽  
High Potassium ◽  
External Potassium ◽  
Sucrose Gap ◽  
Muscle Cell Membrane

(1) The double sucrose-gap method was used to record changes in membrane resistance in intestinal smooth muscle strips. (2) Adrenaline reduced the membrane resistance; it hyperpolarized the membrane and blocked spontaneous and evoked spikes. (3) When the membrane potential was shifted by applying conditioning current, the hyperpolarization produced by adrenaline was larger during depolarization and smaller during hyperpolarization. The hyperpolarization caused by adrenaline was converted into depolarization by 18 to 20 mV conditioning hyperpolarization. (4) The resting membrane resistance was increased in the absence of potassium and in low external chloride (replaced with benzene- or ethane-sulphonate); it was decreased by excess potassium and by nitrate substitution for chloride. (5) The reduction of the membrane resistance by adrenaline was potentiated by high external potassium and by replacement of chloride with nitrate; it was diminished by low external potassium and by replacement of chloride with benzene- or ethane-sulphonate. (6) The hyperpolarization by adrenaline was reduced by raising the external potassium concentration; it was increased by lowering the external potassium concentration. In a solution containing low chloride and high potassium (24 m M ), adrenaline often produced depolarization. (7) It was concluded that adrenaline increases mainly the potassium conductance and also the chloride conductance of the smooth muscle cell membrane. Sodium seemed to be less important for the adrenaline action.

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