Search results for "contraction"
showing 10 items of 1092 documents
Vasodilator Effects of Liriodenine and Norushinsunine, Two Aporphine Alkaloids Isolated from <i>Annona cherimolia,</i>in Rat Aorta
1995
The effect of two aporphines, liriodenine and norushinsunine, isolated from Annona cherimolia, were studied in the rat aorta in order to examine their mechanism of action. Both alkaloids (10–7–10–4 mol/l) showed relaxant effects on the contractions elicited by 10–6 mol/l noradrenaline (NA) or 80 mmol/l KC1, but, while liriodenine showed a nonspecific relaxant action on both spasmogens, norushinsunine was more potent on KC1-induced contraction. In Ca2+-free medium, both alkaloids (0.1 mmol/l) inhibited the responses elicited by NA, but not those elicited by caffeine. This inhibitory action occurred when the alkaloids were present during the release of the Ca2+ internal stores or during the r…
CNS depressant effects, anti-inflammatory activity and anti-cholinergic actions ofSantolina chamaecyparissus extracts
1988
The pharmacological activity of several extracts together with the lyophilized infusion of S. chamaecyparissus ssp. squarrosa were investigated. The lethal dose 50% (LD50), effect on animal metabolism, mechanical and thermic analgesia and spontaneous, anti-inflammatory, and anti-ulcer activity have been determined. Studies on isolated organs (rat duodenum and rat uterus) were also carried out. The hexanic and chloroformic extracts were potent antagonists of the thermic analgesia test; the former extract was also active in the mechanical analgesia test. The chloroformic extract and, to a lesser extent, the ethyl acetate extract and lyophilized infusion demonstrated noteworthy activity as ant…
Inhibition of uterine contractility by guanine-based purines in non-pregnant rats
2022
Growing evidence pointed out that guanine-based purines are able to modulate smooth muscle contractile activity of blood vessels and gastrointestinal tract. Since, so far, possible guanine-based purine modulation of uterine musculature is unknown, the aim of the present study was to investigate in vitro, using organ bath technique, guanosine and guanine efects on spontaneous uterine contraction, and uterine contraction induced by K+-depolarization and oxytocin in a non-pregnant rat. Guanosine, but not guanine, reduced the amplitude of spontaneous contraction of the uterine muscle in a dose-dependent manner. The inhibitory response was antagonized by S-(4-nitrobenzyl)-6-thioinosine (NBTI), a…
Die Wirkung von Theophyllin, Coffein und Theobromin auf Kontraktionskraft, Erregbarkeit, Refrakt�rzeit und Spontanfrequenz des isolierten Herzmuskels…
1956
In the electrically driven papillary muscle of the cat's right ventricle theophylline, caffeine and theobromine exerted a positive inotropic action. Log. dose-effect regression lines for the three drugs were parallel; the effect of theophylline was significantly greater than those of caffeine and theobromine. The range of concentrations used was 1/32–1/2 mM/1.
�ber die Dissoziation von Funktion und Stoffwechsel des isolierten Meerschweinchenherzens unter dem Einflu� von Phosphodiesterase-Hemmstoffen
1970
The influence of several phosphodiesterase-blocking agents on some mechanical and metabolic parameters of isolated perfused guinea pig hearts was studied in order to reinvestigate the repeatedly demonstrated close correlation between these functions. 1. In concentrations which caused 50% inhibition of the phosphodiesterase, theophyllin (1.8×10−4M), ethacrynic acid (4×10−4M) and papaverine (1×10−5M) produced positive inotropic effects by increasing the rate of contraction of the heart muscle (dp/dt). The other substances tested, furosemide (5×10−4M) and hydrochlorothiazide (1.5×10−3M), did not significantly influence the mechanical function of the hearts (Fig.1, upper chart). 2. The coronary…
Ca-abh�ngige Membranpotential�nderungen am Herzen und ihre Bedeutung f�r die elektro-mechanische Kopplung. Versuche mit Tetrodotoxin in Na-haltigen L…
1969
1. Tetrodotoxin (TTX), at a concentration of less than 10−6 g/ml, had no effect on membrane potential and contraction of isolated, thin ventricular trabeculae of sheep and calf hearts. 10−6 to 2 × 10−5 g/ml TTX decreased the rate of rise, over-shoot, and duration (phase of 90% repolarisation) of the action potential and the amplitude of contraction, without change in the resting potential and the plateau (20% repolarisation phase) of the action potential. Excitation block regularly occurred only with 10−5 to 2×10−5 g/ml TTX. 2. In a solution containing Na and TTX (5×10−6-2×10−5 g/ml) graded depolarisation was possible if the preparations were stimulated by square wave pulses of 500 msec dur…
Tonic inhibitory action by nitric oxide on spontaneous mechanical activity in rat proximal colon: involvement of cyclic GMP and apamin-sensitive K+ c…
1999
The cellular mechanisms by which endogenous nitric oxide (NO) modulates spontaneous motility were investigated in rat isolated proximal colon. The mechanical activity was detected as changes in intraluminal pressure. Apamin (1–100 nM) produced a concentration-dependent increase in the amplitude of the spontaneous pressure waves. The maximal contractile effect was of the same degree as that produced by Nω-nitro-L-arginine methyl ester (L-NAME) (100 μM) and the joint application of apamin plus L-NAME had no additive effects. Apamin (0.1 μM) reduced the inhibitory effects (i.e. reduction in the amplitude of the pressure waves) induced by sodium nitroprusside (SNP) (1 nM–10 μM) or 8-Br-cyclic G…
Extracellular ATP Increases <i>L</i>-Carnitine Transport and Content in C2C12 Cells
2008
Extracellular ATP regulates cell proliferation, muscle contraction and myoblast differentiation. ATP present in the muscle interstitium can be released from contracting skeletal muscle cells. <i>L</i>-Carnitine is a key element in muscle cell metabolism, as it serves as a carrier for fatty acid through mitochondrial membranes, controlling oxidation and energy production. Treatment of C2C12 cells with 1 mmol/l of ATP induced a marked increase in <i>L</i>-carnitine uptake that was associated with an increase in <i>L</i>-carnitine content in these cells. These effects were found to be dependent on the density of the cultured cells and on the dose of ATP. The…
Untersuchung von Adenosintriphosphorsäure (ATP), Adenosindiphosphorsäure (ADP), Adenosinmonophosphorsäure (AMP) und Inosinsäure (IMP) in ruhenden und…
1954
A method for the estimation of muscle nucleotides is described. The separation of nucleotides has been accomplished by paper ionophoresis at high voltages, as well as by paper chromatography. Even little changes in the nucleotide content such as the changes in a single muscular contraction can be well observed by this method.
Functional characterization of α1 -adrenoceptor subtypes in vascular tissues using different experimental approaches:a comparative study
2003
The α1-adrenergic responses of rat aorta and tail artery have been analysed measuring the contractility and the inositol phosphate (IP) formation induced by noradrenaline. Three antagonists, prazosin, 5-methylurapidil (α1A selective) and BMY 7378 (α1D selective) have been used in different experimental procedures. Noradrenaline possesses a greater potency inducing contraction and IP accumulation in aorta (pEC50-contraction=7.32±0.04; pEC50-IPs=6.03±0.08) than in the tail artery (pEC50-contraction=5.71±0.07; pEC50-IPs=5.51±0.10). Although the maximum contraction was similar in both tissues (Emax-tail=619.1±55.6 mg; Emax-aorta-698.2±40.8 mg), there were marked differences in the ability of th…