Search results for "Cholin"
showing 10 items of 1261 documents
Cannabinoid CB1 receptor activation modulates spontaneous contractile activity in mouse ileal longitudinal muscle.
2007
The purpose of the present study was to examine whether cannabinoid receptor agonists influence spontaneous contractile activity of longitudinal muscle in mouse ileum in vitro. Isolated segments of mouse ileum displayed spontaneous contractions with an amplitude and frequency of about 300 mg and 30 cpm, respectively. The endocannabinoid anandamide (1-100 microM), the selective cannabinoid CB(1) receptor agonist, ACEA (0.1 microM-10 microM), but not the selective cannabinoid CB(2) receptor agonist, JWH 133 (0.1 microM-10 microM), reduced in a concentration-dependent manner the spontaneous mechanical activity. The inhibitory effect consisted in a decrease of the mean amplitude of longitudinal…
PACAP induces bradycardia in guinea-pig heart by stimulation of atrial cholinergic neurones
1996
Based on previous studies which indicated that pituitary adenylate cyclase activating peptide (PACAP) acts as a positive inotropic and chronotropic substance in different species via the cAMP signal transduction pathway, the objective of the present work was to investigate cAMP-regulated myocardial key proteins in response to PACAP in isolated ventricular cells of the guinea pig. Surprisingly, the two molecular forms of PACAP, PACAP(1-27) and PACAP(1-38), showed no effect on intracellular cAMP-levels, L-type Ca2+ channel current or phosphorylation of troponin inhibitor (TnI) and phospholamban (PLB). Additionally, inotropy of isolated guinea-pig ventricular strips was not affected by the neu…
Autoinhibition of nicotinic release of noradrenaline from postganglionic sympathetic nerves
1970
1. The effects of nicotine, DMPP (1,1-dimethylphenylpiperazine) and acetylcholine (plus atropine) on the isolated rabbit heart were investigated. Heart rate, amplitude of contraction, coronary flow and output of noradrenaline into the perfusate were recorded. Noradrenaline was estimated fluorimetrically. 2. All nicotinic drugs evoked a dose-dependent output of noradrenaline and increased the rate and the amplitude of contraction. Increases of heart rate in response to nicotine and DMPP and increases of amplitude of contraction in response to all nicotinic drugs were clearly related to the output of noradrenaline. 3. The dose-response curves of the noradrenaline output evoked by nicotine, DM…
Inhibition by oxotremorine of acetylcholine resting release from guinea pig-ileum longitudinal muscle strips
1975
1. Longitudinal muscle strips of the guinea-pig ileum were incubated in Tyrode solution containing either DFP or physostigmine as cholinesterase inhibior. After a 90 min preincubation period the acetylcholine resting release into the medium was determined. Acetylcholine was estimated by gas chromatography. 2. The resting release was 0.39 nmol/g×min irrespective of the cholinesterase inhibitor used. In the presence of hexamethonium, or after omission of external calcium, the resting release fell by 50 and 55%, respectively. 3. Oxotremorine (10−5 and 10−4 M) significantly inhibited the resting release of acetylcholine by 25 and 33%, respectively. The inhibitory effect of oxotremorine was comp…
Different muscarinic receptor subtypes modulate proliferation of primary human detrusor smooth muscle cells via Akt/PI3K and map kinases.
2013
While acetylcholine (ACh) and muscarinic receptors in the bladder are mainly known for their role in the regulation of smooth muscle contractility, in other tissues they are involved in tissue remodelling and promote cell growth and proliferation. In the present study we have used primary cultures of human detrusor smooth muscle cells (HDSMCs), in order to investigate the role of muscarinic receptors in HDSMC proliferation. Samples were obtained as discarded tissue from men >65 years undergoing radical cystectomy for bladder cancer and cut in pieces that were either immediately frozen or placed in culture medium for the cell culture establishment. HDSMCs were isolated from samples, propagat…
Antimuscarinic action of quinidine on the heart? A study in myocardial preparations from cat hearts
1984
Quinidine exerts anticholinergic effects which have been ascribed to atropine-like properties of the drug. We have examined the effects of acetylcholine on the force of contraction in isolated heart muscle preparations from cats and compared the inhibitory effects of atropine with those of quinidine. The effects of acetylcholine were antagonized competitively in the presence of atropine. The Schild-plot yielded a straight line; the slope was not significantly different from unity. In the presence of quinidine, the concentration-response curve of acetylcholine was shifted to the right as with atropine, however, the Schild-plot yielded a regression line which was not linear; the slope was sta…
Evidence for the presence of functional protease activated receptor 4 (PAR4) in the rat colon
2004
Background and aims: Protease activated receptors (PARs) have been postulated to play a role during intestinal inflammation. The presence and role played by PAR4 in gastrointestinal functions have not been fully clarified. The aims of this study were: (i) to examine expression of PAR4 in rat proximal colon; (ii) to determine the mechanical effects induced by PAR4 activation in longitudinal muscle; and (iii) to characterise the underlying mechanisms. Methods: PAR4 expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. Mechanical activity was recorded as changes in isometric tension. Results: A PCR product corresponding to the predicted…
Arginine vasopressin, via activation of post-junctional V1 receptors, induces contractile effects in mouse distal colon
2013
The aim of this study was to analyze whether arginine vasopressin (AVP) may be considered a modulator of intestinal motility. In this view, we evaluated, in vitro, the effects induced by exogenous administration of AVP on the contractility of mouse distal colon, the subtype(s) of receptor(s) activated and the action mechanism. Isometric recordings were performed on longitudinal and circular muscle strips of mouse distal colon. AVP (0.001 nM-100 nM) caused concentration-dependent contractile effects only on the longitudinal muscle, antagonized by the V1 receptor antagonist, V-1880. AVP-induced effect was not modified by tetrodotoxin, atropine and indomethacin. Contractile response to AVP was…
Modulation by oxotremorine and atropine of acetylcholine release evoked by electrical stimulation of the myenteric plexus of the guinea-pig ileum
1977
1. The effects of oxotremorine and atropine on the release of acetylcholine from longitudinal muscle strips of the guinea-pig ileum stimulated at frequencies between 0.1 and 3 Hz in the presence of eserine were investigated. In control experiments the acetylcholine output per stimulus declined with increasing frequencies of stimulation. 2. Oxotremorine inhibited the release of acetylcholine in a concentration-dependent fashion. At a concentration of 10−6 M oxotremorine, the release evoked by 0.1 Hz was reduced by 54%. With increasing frequencies of stimulation the inhibitory effect of oxotremorine became smaller. 3. Atropine enhanced the output of acetylcholine evoked by electrical stimulat…
Muscarine receptor types mediating autoinhibition of acetylcholine release and sphincter contraction in the guinea-pig iris.
1990
The potencies of several muscarine receptor antagonists in blocking either the autoinhibition of acetylcholine release or the muscarinic contraction of the sphincter muscle upon acetylcholine release were investigated in the guinea-pig iris. The agonist at pre- or postjunctional muscarine receptors was acetylcholine released upon field stimulation (5.5 Hz, 2 min) of the irides preloaded with 14C-choline. The stimulation-evoked 14C-overflow was doubled in the presence of atropine 0.1 mumol/l but unaffected by the agonist (+/-)-methacholine (50 mumol/l). Thus, under the present stimulation conditions, the autoinhibition of acetylcholine release on the guinea-pig iris cholinergic nerves was ne…