Search results for "relaxation"
showing 10 items of 1162 documents
Effects of inhibitors of cGMP-dependent protein kinase in atrial heart and aortic smooth muscle from rats
1995
Several activators of cGMP-dependent protein kinase (protein kinase G) such as 8-Br-cGMP reduced force of contraction in rat left atria. Inhibitors of protein kinase G antagonized the negative inotropic effect of 8-Br-cGMP but not of acetylcholine in atria. However, the acetylcholine-induced relaxation in aortic rings was significantly inhibited by protein kinase G inhibition. It is concluded that the reduction by 8-Br-cGMP of force of contraction in atria is related to activation of protein kinase G. In response to acetylcholine, activation of protein kinase G is probably a major step in smooth muscle relaxation but is not involved in the reduction of force of contraction in atria.
Echocardiography to estimate high filling pressure in patients with heart failure and reduced ejection fraction
2020
Aims: Echocardiographic assessment of left ventricular filling pressures is performed using a multi-parametric algorithm. Unselected sample of patients with heart failure with reduced ejection fraction (HFrEF) patients may demonstrate an indeterminate status of diastolic indices making interpretation challenging. We sought to test improvement in the diagnostic accuracy of standard and strain echocardiography of the left ventricle and left atrium (LA) to estimate a pulmonary capillary wedge pressure (PCWP) > 15 mmHg in patients with HFrEF. Methods and results: Out of 82 consecutive patients, 78 patients were included in the final analysis and right heat catheterization, and echocardiogram…
Characteristics of histamine tachyphylaxis in rat uterine smooth muscle.
2002
Objective and design: To study both the desensitisation induced by short-term exposure to histamine and the mechanism responsible in the isolated rat uterus.¶Material: Precontracted isolated uterus (37 mM KCl) from oestrogenised Wistar rats were used.¶Treatment: Repetitive responses to histamine (10–6, 10–5, 10–4, 10–3 M), dimaprit and clonidine (10–4 M) were tested at 15, 30, 45 and 105 min., with their modifications by (5 mg/ kg, 24 h before sacrifice) reserpine, 10–7 M propranolol, 10–8 M atropine, and 10–6 M indomethacin. Dose-response curves for adrenaline were carried out as standard protocol.¶Methods: In vitro techniques (de Jalon's solution, 31°C, carbogen, isotonic registration, re…
Thermal increase in the oral mucosa and in the jawbone during Nd:YAG laser applications. Ex vivo study
2012
Objective: Literature reports bactericidal and biostimulant effects for Nd:YAG laser procedures on bone and oral mucosa but the possible overheating can cause damage to anatomical structures. The aim of the study is the evaluation of thermal increase in different levels of oral tissues: mucosa, periosteum and bone during defocused application of Nd:YAG laser at different parameters. Study Design: Superficial thermal evaluation was performed in pig jaws with a thermal camera device; deep thermal evaluation was realized by 4 thermocouples placed at a subperiosteal level and at 1,2 and 4 mm depth in the jaw bone. Laser applications of 1 minute were performed 5 times (with a pause of 1 minute) …
Bronchodilator and anti-inflammatory activities of SCA40: studies in human isolated bronchus, human eosinophils, and in the guinea-pig in vivo.
1998
There is currently interest in the use of inhibitors of cyclic nucleotide phosphodiesterases (PDE) as potential anti-asthma agents. In this study we examined the effects of SCA40 (6-bromo-8-methylaminoimidazol-[1,2-a] pyrazine-2-carbonitrile), a preferential inhibitor of PDE 3 also endowed with PDE 4 and 5 inhibitory activities, on isolated bronchus and eosinophil functions and in an animal model of asthma. SCA40 (1 nM-0.1 mM) produced concentration-dependent inhibition of spontaneous and stimulated tone of human isolated bronchus and reached a maximal relaxation similar to that of theophylline (3 mM). The potency (-log EC50 values) of SCA40 against spontaneous tone (6.52 +/- 0.10) was grea…
Ca2+ entry blockers inhibit prostaglandin F2 alpha-induced cerebrovascular contractile responses in goats.
1991
We examined the effects of extracellular Ca2+ withdrawal and of Ca2+ entry blockers on goat cerebrovascular responses to prostaglandin F2 alpha (PGF2 alpha). We measured isometric tension in isolated middle cerebral arteries, and cerebral blood flow (CBF) in unanesthetized animals. PGF2 alpha produced concentration-dependent contractions of isolated arteries. The contractions were partially inhibited by incubation in Ca(2+)-free medium (by 63.1 +/- 1.8% without ethyleneglycol-bis-(beta-amino-ethylether)-N,N,N',N'-tetra-a cetate (EGTA), and by 82.4 +/- 3.7% with EGTA). The Ca2+ entry blockers inhibited PGF2 alpha-elicited contraction and relaxed PGF2 alpha-precontracted arteries (nicardipine…
Intervention of two voltage-dependent calcium-entry pathways in the contractile response to acetylcholine and KCl in rat uterus.
1994
The contractile response of rat uterine smooth muscle was investigated. Verapamil and diltiazem concentration-dependently relax the sustained contractions induced by KCl (56 mmol/l) or acetylcholine (10(-4) mol/l). This inhibitory effect was not not freely reversed by washing the tissue and subsequently no contractile response was obtained in depolarized tissue, but a lower biphasic response (phasic and tonic) to acetylcholine was observed. Addition of cumulative concentrations of CaCl2 (1.2-19.2 mmol/l) induced a partial recovery of the contractile response to acetylcholine or KCl, but addition of MgCl2 (1.2-19.2 mmol/l did not. When the channel was reactivated by a third addition of KCl o…
Comparative study of the rat uterine smooth muscle relaxant activity of three bisbenzyltetrahydroisoquinolines with tetrandrine
1993
Abstract The relaxant activity of three bisbenzyltetrahydroisoquinolines—obaberine, popisonine and lindoldhamine—was examined in rat isolated uterus and their inhibitory potencies were compared with that of tetrandrine. All alkaloids tested relaxed KCl-depolarized rat uterus and totally or partially inhibited oxytocin-induced rhythmic contractions. The degree of methylation of the free phenolic hydroxy groups and the loss of one diarylether bridge influence the potency of relaxant action of these alkaloids. Only alkaloids with absolute configuration 1R,1′S or 1R1′R acted intracellularly, promoting relaxation of contractile responses induced by oxytocin or vanadate in a Ca2+-free medium.
Assessment of skeletal muscle fatigue of road maintenance workers based on heart rate monitoring and myotonometry
2006
Abstract Objective This research work is dedicated to occupational health problems caused by ergonomic risks. The research object was road building industry, where workers have to work very intensively, have long work hours, are working in forced/constrained work postures and overstrain during the work specific parts of their bodies. The aim of this study was to evaluate the work heaviness degree and to estimate the muscle fatigue of workers after one week work cycle. The study group consisted of 10 road construction and maintenance workers and 10 pavers aged between 20 and 60 years. Methods Physical load were analyzed by measuring heart rate (HR), work postures (OWAS) and perceived exertio…