Rhythmicity and Tension Development of Spontaneous Contracting Capillaries in the Mesentery of Frogs

1984 ◽  
pp. 755-759 ◽  
Author(s):  
H. Weigelt ◽  
K. E. Wohlfarth-Bottermann
Keyword(s):  
Tension Development

Decreased Myocyte Tension Development and Calcium Responsiveness in Rat Right Ventricular Pressure Overload

Circulation ◽  
1997 ◽  
Vol 95 (9) ◽  
pp. 2312-2317 ◽  
Author(s):  
Dongsheng Fan ◽  
Thomas Wannenburg ◽  
Pieter P. de Tombe
Keyword(s):  
Right Ventricular ◽  
Pressure Overload ◽  
Ventricular Pressure ◽  
Tension Development

scholarly journals FFAR1 activation attenuates histamine-induced myosin light chain phosphorylation and cortical tension development in human airway smooth muscle cells

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Shengjie Xu ◽  
Anthony Schwab ◽  
Nikhil Karmacharya ◽  
Gaoyuan Cao ◽  
Joanna Woo ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Airway Hyperreactivity ◽  
Human Airway Smooth Muscle ◽  
Tension Development ◽  
Cortical Tension ◽  
Human Airway ◽  
Mlc Phosphorylation

Abstract Background Activation of free fatty acid receptors (FFAR1 and FFAR4) which are G protein-coupled receptors (GPCRs) with established (patho)physiological roles in a variety of obesity-related disorders, induce human airway smooth muscle (HASM) cell proliferation and shortening. We reported amplified agonist-induced cell shortening in HASM cells obtained from obese lung donors. We hypothesized that FFAR1 modulate excitation–contraction (EC) coupling in HASM cells and play a role in obesity-associated airway hyperresponsiveness. Methods In HASM cells pre-treated (30 min) with FFAR1 agonists TAK875 and GW9508, we measured histamine-induced Ca2+ mobilization, myosin light chain (MLC) phosphorylation, and cortical tension development with magnetic twisting cytometry (MTC). Phosphorylation of MLC phosphatase and Akt also were determined in the presence of the FFAR1 agonists or vehicle. In addition, the effects of TAK875 on MLC phosphorylation were measured in HASM cells desensitized to β2AR agonists by overnight salmeterol treatment. The inhibitory effect of TAK875 on MLC phosphorylation was compared between HASM cells from age and sex-matched non-obese and obese human lung donors. The mean measurements were compared using One-Way ANOVA with Dunnett’s test for multiple group comparisons or Student’s t-test two-group comparison. For cortical tension measurements by magnetic twisted cytometry, mixed effect model using SAS V.9.2 was applied. Means were considered significant when p ≤ 0.05. Results Unexpectedly, we found that TAK875, a synthetic FFAR1 agonist, attenuated histamine-induced MLC phosphorylation and cortical tension development in HASM cells. These physiological outcomes were unassociated with changes in histamine-evoked Ca2+ flux, protein kinase B (AKT) activation, or MLC phosphatase inhibition. Of note, TAK875-mediated inhibition of MLC phosphorylation was maintained in β2AR-desensitized HASM cells and across obese and non-obese donor-derived HASM cells. Conclusions Taken together, our findings identified the FFAR1 agonist TAK875 as a novel bronchoprotective agent that warrants further investigation to treat difficult-to-control asthma and/or airway hyperreactivity in obesity.

Rate of muscle tension development and release under extreme temperatures

1962 ◽  
Vol 19 (5) ◽  
pp. 330-336 ◽  
Author(s):  
David H. Clarke ◽  
Joseph Royce
Keyword(s):  
Muscle Tension ◽  
Extreme Temperatures ◽  
Tension Development

The Threshold for Potassium-Induced Contractures of Frog Skeletal Muscle. Potentiation of Potassium-Induced Contractures by Preexposure to Subthreshold Potassium Concentrations

1972 ◽  
Vol 50 (1) ◽  
pp. 37-44 ◽  
Author(s):  
E. C. Vos ◽  
G. B. Frank
Keyword(s):  
Skeletal Muscle ◽  
Potassium Concentration ◽  
Ringer Solution ◽  
Frog Skeletal Muscle ◽  
Contractile Apparatus ◽  
Tension Development ◽  
Eventual Loss ◽  
Active Processes ◽  
Muscle Potentiation ◽  
Small Bundle

A brief exposure (about 10–30 s) of a frog's toe muscle or a small bundle of fibers from the semi-tendinosus muscle to just subthreshold potassium concentrations potentiated contractures subsequently produced by exposing the muscles to a potassium concentration slightly above the threshold. The contractures thus potentiated had greater maximum tensions, and greater rates of tension development and relaxation than control contractures elicited by the same final potassium concentration. The resistance to stretch (R.T.S.) in the first few seconds of the potentiated contractures was about twice that of control contractures. Maximum potentiation occurred with preexposures of about 30 s; longer preexposures led to a decrease of potentiation and eventually to a depression of the contracture. The potentiation was not immediately abolished when the muscle was reexposed to Ringer solution but persisted for 2 min or longer (the 'washout effect'). It was concluded that exposing a muscle to low subcontracture threshold concentrations of potassium for a few seconds primes the intracellular contractile apparatus, probably by causing an increased sarcoplasmic concentration of Ca2+ ions, resulting in a potentiation of subsequently induced submaximal potassium contractures. The increase in metabolism (or 'Solandt effect') seen under these conditions is temporally related to the decline and eventual loss of the potentiation and is probably a reflection of active processes involved in reducing the sarcoplasmic concentration of Ca2+ ions.

The Effects of Acclimation Temperature on a Neuromuscular System of the Crayfish, Astacus Leptodactylus

1979 ◽  
Vol 78 (1) ◽  
pp. 281-293
Author(s):  
MIKKO HARRI ◽  
ERNST FLOREY
Keyword(s):  
Membrane Lipids ◽  
Characteristic Temperature ◽  
Resting Membrane Potential ◽  
Acclimation Temperature ◽  
Muscle Fibres ◽  
Astacus Leptodactylus ◽  
Tension Development ◽  
Temperature Range ◽  
Wide Range ◽  
Warm Acclimation

1. Crayfish, Astacus leptodactylus, were acclimated to 12 °C and to 25 °C. Nerve muscle preparations (closer muscle of walking legs) were subjected to temperatures ranging from 6 to 32 °C. 2. The resting membrane potential of muscle fibres was found to increase with temperature in a linear manner, but with a change in slope at around 170 in cold-acclimated preparations, and around 24 °C in warm-acclimated ones. 3. Temperature acclimation shifted the temperature range of maximal amplitudes of fast and slow e.j.p.s toward the acclimation temperature. Optimal facilitation of slow e.j.p.s also occurred near the respective acclimation temperature. 4. E.j.p. decay time is nearly independent of temperature in the upper temperature range but increases steeply when the temperature falls below a critical range around 17 °C in preparations from cold-acclimated animals, and around 22 °C after acclimation to 25 °C. 5. Peak depolarizations reached by summating facilitated e.j.p.s are conspicuously independent of temperature over a wide range (slow and fast e.j.p.s of cold-acclimated preparations, fast e.j.p.s of warm-acclimated ones) which extends to higher temperatures after warm acclimation in the case of fast e.j.p.s. In warm-acclimated preparations the peak depolarization of slow e.j.p.s first falls then rises and falls again as the temperature increases from 8 to 32 °C. 6. Tension development elicited by stimulation of the slow axon at a given frequency reaches maximal values at the lower end of the temperature range in cold-acclimated preparations. The maximum is shifted towards 20 °C after warm acclimation. Fast contractions decline with temperature; possible acclimation effects are masked by the great lability of fast contractions in warm-acclimated preparations. 7. It is suggested that changes in the composition of membrane lipids may be responsible for the effects of acclimation on the electrical parameters and their characteristic temperature dependence.

Effects of calcium on isolated mammalian heart

1964 ◽  
Vol 207 (3) ◽  
pp. 716-720 ◽  
Author(s):  
Ernst Seifen ◽  
Werner Flacke ◽  
Milton H. Alper
Keyword(s):  
Heart Rate ◽  
Calcium Concentration ◽  
Conduction Block ◽  
Filling Pressure ◽  
Conduction Time ◽  
Tension Development ◽  
Ventricular Filling Pressure ◽  
Plasma Calcium Concentration ◽  
Ventricular Filling ◽  
Lung Preparation

The effect of calcium on heart rate, A-V conduction, and contractility was studied in the dog's heart-lung preparation. Normal plasma calcium concentration was 2.71 ± 0.20 mm (N = 25). Heart rate was increased by calcium in the range from 1.6 to 14.0 mm and fell at still higher levels. A-V conduction time was shortest at calcium concentration slightly above normal, and decreased at higher as well as lower concentrations. At levels above 17 mm conduction block, fibrillation or cardiac arrest, or both, occurred. Contractile force was markedly reduced at low calcium. Increase of calcium lowered ventricular filling pressure, increased the rate of tension development and of relaxation, and shortened duration of contraction. The effects of calcium were not altered by pretreatment with reserpine (2 x 0.5 mg/kg, s.c., given 48 and 24 hr prior to experiment) and were not influenced by atropine (2–5 mg). The effect of calcium on contractility was fully developed 100 sec after administration; the effect on sinoatrial rhythm was established only after 4.4 ± 0.54 min.

Effects of muscle shortening on the responses of cat tendon organs to unfused contractions

1988 ◽  
Vol 59 (5) ◽  
pp. 1510-1523 ◽  
Author(s):  
G. Horcholle-Bossavit ◽  
L. Jami ◽  
J. Petit ◽  
R. Vejsada ◽  
D. Zytnicki
Keyword(s):  
Motor Units ◽  
Tension Development ◽  
Golgi Tendon Organs ◽  
Dynamic Sensitivity ◽  
Single Motor Units ◽  
Muscle Shortening ◽  
Length Changes ◽  
Tendon Organs ◽  
Tendon Organ ◽  
Shortening Contractions

1. The discharges from individual Golgi tendon organs of peroneus tertius and brevis muscles were recorded in anesthetized cats. Responses to unfused isometric contractions of single motor units and combinations of motor units were compared with responses to contractions eliciting muscle shortening (i.e., shortening contractions). 2. In 75% of the examined instances, the effect of muscle shortening during unfused contractions was a slight decrease in tendon organ activation, in keeping with the reduction of contractile tension recorded at the muscle tendon. In other instances there was either no change in tendon organ response or, in less than 10% of instances, a slight increase For two motor units eliciting similar activation of a given tendon organ under isometric conditions, the effect of shortening contraction was not necessarily the same. 3. The reductions observed in tendon organ discharges upon muscle shortening were less than proportional to the reductions of contractile tension and difficult to correlate with the properties of motor units, as determined under isometric conditions. The present observations suggest three main reasons for this lack of relation. 4. The first reason depended on the properties of motor units, in that the relation between length changes and tension changes was not the same for all units. Two motor units developing similar isometric tensions did not necessarily produce the same degree of muscle shortening. Some units produced relatively significant shortening without much loss of tension. 5. Second, the dynamic sensitivity of tendon organs is known to exert a major influence on their responses to isometric unfused contractions, accounting for 1:1 driving of discharge during tension oscillations and high frequency bursts upon abrupt increase of tension. Although less tension was produced and the rate of tension development was slower in shortening contractions, similar manifestations of the dynamic sensitivity of tendon organs were observed. In such cases, the responses of tendon organs were the same whether or not the muscle shortened during contraction. 6. Third, when several motor units were stimulated in combination, the unloading influences of in-parallel units were facilitated by muscle shortening so that unloading effects, which were hardly visible under isometric conditions became evident during shortening contractions.

Calcium-dependent resistance to stretch and stress relaxation in resting smooth muscles

1976 ◽  
Vol 231 (5) ◽  
pp. 1501-1508 ◽  
Author(s):  
MJ Siegman ◽  
TM Butler ◽  
SU Mooers ◽  
RE Davies
Keyword(s):  
Stress Relaxation ◽  
Smooth Muscles ◽  
Muscle Length ◽  
Taenia Coli ◽  
Tetraacetic Acid ◽  
Active Tension ◽  
Tension Development ◽  
Calcium Dependent ◽  
Mechanical Responses ◽  
State Force

Mechanical responses to stretch and length-tension relations were examined in rabbit taenia coli, mesenteric vein, aorta, and myometrium and in guinea pig taenia coli made atonic by incubation in Krebs-bicarbonate solution at 20-22 degrees C. When stretched 10% of the length at which maximum active tension is observed (Lo) in 0.5 s, the muscles showed a transient large force (resistance to stretch) that decayed to a new constant level within minutes (stress relaxation). The resistance to stretch decreased markedly in Ca2+-free [disodium ethylene glycolbis-(beta-aminoethylether)-N,N-tetraacetic acid (EGTA)] Krebs but was restored in normal Krebs solution. Calcium removal did not affect the passive length-tension curve. The absence of Ca2+ did not change the steady-state force maintained by the muscle; thus stretch resistance was not due to tone. Blockade of Ca2+ influx associated with electrical activity with 5-[3,4-dimethoxyphenethyl)methylamino]-2-(3,4,5-trimethoxyphenyl-2-isoprop ylvaleronitrile (D-600) and of Ca2+ release from intracellular sites with thymol (1 mM) completely blocked contraction but did not alter the responses to stretch, thus dissociating the responses to stretch from these processes and tension development. The Ca2+-dependent stress relaxation showed a dependence on muscle length similar to that for active tension development. Except at long muscle lengths, where connective tissue markedly affects length-tension relations, most of the "viscoelasticity" of these smooth muscles is dependent on calcium and may be largely due to the straining of crossbridges that are attached, but not generating a net force, in the resting state.

Sign in / Sign up

Export Citation Format

Share Document