Search results for "Smooth"
showing 10 items of 710 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…
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…
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…
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…
Mode and mechanism of neurotensin action in rat proximal colon
1997
Abstract This study examined the mechanism of action of neurotensin on intraluminal pressure in rat proximal colon. The direct and indirect contractile response to neurotensin (100 nM) was abolished in Ca 2+ -free solution, and was antagonized by nifedipine (1–5–10 nM) and potentiated by Bay K 8644 (methyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyridine-5-carboxylate) (10–100–1000 nM). Neurotensin, in the presence of nifedipine (10 nM) and atropine (1 μM), induced a tetrodotoxin-insensitive inhibitory effect, which was antagonized by SR 48692 (2[(1-(7-chloro-4-quinolinyl)-5-(2,6-dimethoxy-phenyl)pyrazol-3-yl) carbonyl amino]tricyclo (3.3.1.1. 3.7 ) decan-2-carboxylic a…
Integration of a Dirac comb and the Bernoulli polynomials
2016
Abstract For any positive integer n , we consider the ordinary differential equations of the form y ( n ) = 1 − Ш + F where Ш denotes the Dirac comb distribution and F is a piecewise- C ∞ periodic function with null average integral. We prove the existence and uniqueness of periodic solutions of maximal regularity. Above all, these solutions are given by means of finite explicit formulae involving a minimal number of Bernoulli polynomials. We generalize this approach to a larger class of differential equations for which the computation of periodic solutions is also sharp, finite and effective.
Biphasic Erk1/2 activation sequentially involving Gs and Gi signaling is required in beta3-adrenergic receptor-induced primary smooth muscle cell pro…
2013
Abstract The beta3 adrenergic receptor (B3-AR) reportedly induces cell proliferation, but the signaling pathways that were proposed, involving either Gs or Gi coupling, remain controversial. To further investigate the role of G protein coupling in B3-AR induced proliferation, we stimulated primary human myometrial smooth muscle cells with SAR150640 (B3-AR agonist) in the absence or presence of variable G-protein inhibitors. Specific B3-AR stimulation led to an Erk1/2 induced proliferation. We observed that the proliferative effects of B3-AR require two Erk1/2 activation peaks (the first after 3 min, the second at 8 h). Erk1/2 activation at 3 min was mimicked by forskolin (adenylyl-cyclase a…