Search results for "Contraction"
showing 10 items of 1092 documents
Interplay between PACAP and NO in mouse ileum
2003
Abstract We investigated the possibility that pituitary adenylate cyclase activating peptide (PACAP) has a role in the control of contractility in the mouse ileum. PACAP-(1-27) produced tetrodotoxin (TTX)-insensitive, concentration-dependent reduction of the amplitude of the spontaneous contractions of longitudinal muscle up to their complete disappearance. This effect was inhibited by PACAP-(6-38), PACAP receptor antagonist, and by apamin, blocker of small-conductance Ca2+-activated K+-channels. Nω-nitro- l -arginine methyl ester (L-NAME), nitric oxide (NO) synthase inhibitor, reduced the PACAP-inhibitory response, and the joint application of apamin plus L-NAME produced additive effects. …
Differences in the nitric oxide/soluble guanylyl cyclase signalling pathway in the myocardium of neonatal and adult rats
2000
Abstract The effects of a nitric oxide-donor, S -nitroso- N -acetylpenicillamine, and a direct activator of soluble guanylyl cyclase, 3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole (YC-1), on force of contraction ( F c ) and L-type Ca 2+ currents ( I Ca(L) ) were investigated in myocardial preparations from neonatal and adult rats. Since hearts from adult and neonatal animals contained 160 and 47 mg/100 g wet weight myoglobin, respectively, its possible interaction with both drugs was also investigated. Both S -nitroso- N -acetylpenicillamine (100 μM) and YC-1 (30 μM) were ineffective in myocardial preparations from adult rats but reduced the magnitude of I Ca(L) and F c in preparations fr…
Antagonism of calcium by zinc in guinea-pig isolated taenia caeci and trachealis muscle
1989
1 In guinea-pig isolated taenia caeci and trachealis bathed in a K+-rich, Ca2+-free medium, CaCl2 (0.01-10 mM) produced a concentration-dependent contraction. Zn2+ (0.01-1 mM), Cd2+ (0.01-1 mM), verapamil (0.01-100 microM) and trifluoperazine (1-100 microM) were effective antagonists of CaCl2-induced responses. 2 Zn2+ and Cd2+ in concentrations from 0.01 to 1 mM were without effect on the tone of taenia and trachea in normal Tris solution. Conversely, Zn2+ and Cd2+, in concentrations of 1 mM, caused contraction of these tissues in a K+-rich, Ca2+-free medium. Zn2+ (1 mM)-induced contractions of taenia and trachea were completely inhibited by verapamil (10 microM). 3 In taenia and trachea sk…
Muscle fiber-type distribution predicts weight gain and unfavorable left ventricular geometry: a 19 year follow-up study
2006
Abstract Background Skeletal muscle consists of type-I (slow-twitch) and type-II (fast-twitch) fibers, with proportions highly variable between individuals and mostly determined by genetic factors. Cross-sectional studies have associated low percentage of type-I fibers (type-I%) with many cardiovascular risk factors. Methods We investigated whether baseline type-I% predicts left ventricular (LV) structure and function at 19-year follow-up, and if so, which are the strongest mediating factors. At baseline in 1984 muscle fiber-type distribution (by actomyosin ATPase staining) was studied in 63 healthy men (aged 32–58 years). The follow-up in 2003 included echocardiography, measurement of obes…
The new clinical standard of integrated quadruple stress echocardiography with ABCD protocol
2018
Abstract Background The detection of regional wall motion abnormalities is the cornerstone of stress echocardiography. Today, stress echo shows increasing trends of utilization due to growing concerns for radiation risk, higher cost and stronger environmental impact of competing techniques. However, it has also limitations: underused ability to identify factors of clinical vulnerability outside coronary artery stenosis; operator-dependence; low positivity rate in contemporary populations; intermediate risk associated with a negative test; limited value of wall motion beyond coronary artery disease. Nevertheless, stress echo has potential to adapt to a changing environment and overcome its c…
Cross-sectional area of the paraspinal muscles and its association with muscle strength among fighter pilots: a 5-year follow-up
2019
Background: A small cross sectional area (CSA) of the paraspinal muscles may be related to low back pain among military aviators but previous studies have mainly concentrated on spinal disc degeneration. Therefore, the primary aim of the study was to investigate the changes in muscle CSA and composition of the psoas and paraspinal muscles during a 5-year follow up among Finnish Air Force (FINAF) fighter pilots. Methods: Study population consisted of 26 volunteered FINAF male fighter pilots (age: 20.6 (±0.6) at the baseline). The magnetic resonance imaging (MRI) examinations were collected at baseline and after 5 years of follow-up. CSA and composition of the paraspinal and psoas muscles wer…
Effects of alkylxanthines on contractility of diaphragm fibres isolated from normal and sensitized guinea-pigs.
1993
Abstract This study investigates the effects of alkylxanthines on twitch tension generated by electrical stimulation (supramaximal pulses, 0·2 ms duration, 1 Hz) of diaphragm muscle fibres isolated from normal and actively-sensitized guinea-pigs. Caffeine, theophylline and theobromine increased, in a concentration-dependent manner (50–500 μm), twitch tension in normal and sensitized diaphragm. Caffeine (500 μm) enhanced contractility to a greater extent than theophylline or theobromine. Twitch potentiation by caffeine (500 μm) was significantly greater in sensitized diaphragm. Verapamil (0·1–100 μm) did not alter twitch contractions in the absence or presence of alkylxanthines in normal or …
A1 receptors mediate adenosine inhibitory effects in mouse ileum via activation of potassium channels.
2008
Abstract Aims We investigated the effects induced by exogenous adenosine on the spontaneous contractile activity of the longitudinal muscle of a mouse ileum, the receptor subtypes activated, the involvement of enteric nerves and whether opening of K + channels was a downstream event leading to the observed effects. Main methods Mechanical responses of the mouse ileal longitudinal muscle to adenosine were examined in vitro as changes in isometric tension. Key findings Adenosine caused a concentration-dependent reduction of the spontaneous contraction amplitude of the ileal longitudinal muscle up to its complete disappearance. This effect induced was markedly reduced by an A 1 receptor antago…
Mechanical jumping power in young athletes.
1987
Mechanical jumping power was determined for 286 young male athletes representing six sports events and ranging in calendar and skeletal ages from 8.8 to 17.1 and from 7.8 to 18.1 years, respectively. The subjects performed successive maximal vertical jumps on a contact mat for 30 s. The number of jumps and their cumulative flight time after 15 and 30 s were used for calculations of mechanical power. The jumping performances of the young athletes were found to be reproducible from the age of 10-12 years in respect to the angular displacement of the knee and duration of contact. Absolute mechanical power, as well as power related to body weight, increased with calendar and skeletal ages. Of t…
Effect of isometric strength training of mechanical, electrical, and metabolic aspects of muscle function.
1978
Monozygous twin pairs (two female and four male) were used in a strength training study so that one member of each pair served as training subject (TS) and the other members as nonexercising controls (CS). TS trained four times a week for 12 weeks with maximal isometric knee extensions of the right leg. The parameters studied included muscle strength, endurance time, electromyographic activity, and activities of several key enzymes in nonoxidative and oxidative muscle metabolism. The results disclosed that in addition to a 20% increase in isometric knee extension strength in the trained leg of TS, an average increase of 11% was observed in strength of TS untrained leg. CS did not demonstrat…