Search results for "Plexus"
showing 10 items of 164 documents
Two types of receptors for 5-hydroxytryptamine on the cholinergic nerves of the guinea-pig myenteric plexus
1985
Abstract The effects of 5-hydroxytryptamine (5-HT) on spontaneous and electrically-evoked release of [3H]-acetylcholine (ACh) from guinea-pig myenteric plexus preparations preincubated with [3H]-choline have been investigated in the absence of cholinesterase inhibitors. 5-HT caused a transient increase in spontaneous release and an inhibition of the electrically-evoked release of [3H]-ACh. The 5-HT-induced contractions of the longitudinal muscle were clearly related to the increase in spontaneous release. The inhibitory effect was not due to activation of alpha-adrenoceptors since it was also observed in the presence of tolazoline and on strips from reserpine-pretreated guinea-pigs. After d…
The effects of racemic bethanechol and its (R)- and (S)-enantiomers on pre- and postjunctional muscarine receptors in the guinea-pig ileum
1985
The effect of racemic bethanechol and its (R)- and (S)-enantiomers on smooth muscle contraction and outflow of [3H]-acetylcholine were studied in the guinea-pig myenteric plexus-longitudinal muscle preparation that had been preincubated with [3H]-choline. (S)-, racemic, and (R)-bethanechol caused concentration-dependent contractions of the longitudinal muscle. The potency ratio of the strong isomer (S) to the weak one (R) was 915. Racemic and (S)-bethanechol concentration-dependently inhibited the evoked outflow of [3H]-acetylcholine. Racemic bethanechol was more potent than (S)-bethanechol. (R)-bethanechol up to a concentration of 1 mM did no affect the evoked outflow of [3H]-acetylcholine…
Distribution of origin of nitric oxide synthase-immunoreactive nerve fibers in the rat epididymis.
1996
Abstract Distribution of neuronal nitric oxide synthase-immunoreactive (nNOS-IR) nerve fibers and somata in the rat epididymis and major pelvic ganglia was studied by immunohistochemical methods. In the epididymis, the supply of nNOS-IR fibers was highest in the cauda and became progressively fewer toward the caput. In the cauda and corpus, nNOS-IR fibers were distributed throughout the subepithelial tissues and around the epithelium. The pattern of distribution of vasoactive intestinal polypeptide (VIP)- and tyrosine hydroxylase (TH)-immunoreactive fibers in the epididymis was similar but the latter was generally more numerous in a given region as compared to that of nNOS-IR fibers. A popu…
Cholinergic and GABAergic regulation of nitric oxide synthesis in the guinea pig ileum.
1999
Nitric oxide (NO) synthesis was examined in intact longitudinal muscle-myenteric plexus preparations of the guinea pig ileum by determining the formation of [3H]citrulline during incubation with [3H]arginine. Spontaneous [3H]citrulline production after 30 min was 80–90 dpm/mg, which constituted ∼1% of the tissue radioactivity. Electrical stimulation (10 Hz) led to a threefold increase in [3H]citrulline formation. Removal of calcium from the medium or addition of N G-nitro-l-arginine strongly inhibited both spontaneous and electrically induced production of [3H]citrulline. TTX reduced the electrically induced but not spontaneous [3H]citrulline formation. The electrically induced formation o…
Increase by ?-adrenolytic drugs of acetylcholine release evoked by field stimulation of the guinea-pig ileum
1979
The release of acetylcholine evoked by field stimulation of the guinea-pig ileum (3 Hz) is increased by yohimbine and tolazoline but not affected by phentolamine. It is proposed that yohimbine and tolazoline by blocking alpha-adrenoceptors of the cholinergic nerves abolish the inhibition caused by endogenous noradrenaline, and thus facilitate the output of acetylcholine.
Differential effects of nitric oxide donors on basal and electrically evoked release of acetylcholine from guinea-pig myenteric neurones
1996
1. The effects of the nitric oxide (NO) donors, 3-morpholino-sydnonimine (SIN-1), S-nitroso-N-acetylpenicillamine (SNAP) and sodium nitroprusside on basal and electrically evoked release of [3H]-acetylcholine were studied in myenteric plexus longitudinal muscle preparations of the guinea-pig small intestine preincubated with [3H]-choline. 2. The NO donors concentration-dependently increased basal release of [3H]-acetylcholine. The increase in release was calcium-dependent and was prevented in the presence of tetrodotoxin. Superoxide dismutase (150 u ml-1) potentiated the effect of SIN-1. The selective inhibitor of soluble guanylyl cyclase, 1H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one (OD…
Nitric oxide-sensitive guanylyl cyclase inhibits acetylcholine release and excitatory motor transmission in the guinea-pig ileum
1997
Abstract This study examined the mechanism through which nitric oxide inhibits the release of acetylcholine and excitatory motor neurotransmission in the guinea-pig ileum. The selective inhibitor of nitric oxide-sensitive guanylyl cyclase, 1 H -[1,2,4]oxadiazolo[4,3- a ]quinoxalin-1-one (ODQ), concentration-dependently enhanced both basal release (−log EC 50 : 6.8) and electrically (10 Hz) -evoked release (−log EC 50 : 6.0) of [ 3 H]acetylcholine from longitudinal muscle-myenteric plexus preparations preincubated with [ 3 H]choline. The increase by ODQ of basal release appeared to be exocytotic since it was prevented by tetrodotoxin (300 nM) and absence of calcium from the superfusion mediu…
The effects of LSD in the guinea-pig ileum
1985
The effects of lysergic acid diethylamide (LSD) on acetylcholine release and on smooth muscle tone were studied in the myenteric plexus-longitudinal muscle preparation of the guinea pig. LSD (0.01-10 microM) depressed in a concentration-dependent manner the electrically-evoked [3H]-acetylcholine outflow from strips preincubated with [3H]-choline. The maximal effect was a 45% inhibition by 1 microM LSD. The spontaneous outflow was not affected. Metitepine competitively antagonized (pA2 8.0) the LSD-induced reduction of the evoked outflow. Tolazoline and mepyramine did not affect the inhibitory action of LSD. The contractions in response to electrical stimulation were enhanced by 34% in the p…
Indication and technique for the reconstruction of nerve defects in head and neck.
1974
Summary Although the results of peripheral nerve repair have been greatly improved in the last years following the introduction of microsurgery and increased application of free autologous nerve transplants, the use of restorative neuroplasty in maxillofacial surgery has been limited. Prompted by the successful reports on modern neuroplasty, we have introduced the use of autologous nerve transplant to bridge lesions of various cranial nerves. Our experience is based on the treatment of traumatic and tumour-induced defects of the facial nerve, inferior alveolar nerve, accessory and lingual nerve. The anastomosis of nerve was accomplished exclusively under the surgical microscope and microsur…
Differential effects of calcium channel antagonists (omega-conotoxin GVIA, nifedipine, verapamil) on the electrically-evoked release of [3H]acetylcho…
1990
Electrically-evoked release of [3H]acetylcholine from autonomic neurons (myenteric plexus), motoneurons (phrenic nerve) and the central nervous system (neocortex) was investigated in the presence and absence of the calcium channel antagonists omega-conotoxin GVIA, nifedipine and verapamil, whereby the same species (rat) was used in all experiments. Release of [3H]acetylcholine was measured after incubation of the tissue with [3H]choline. omega-Conotoxin GVIA markedly reduced (70%) the evoked release of [3H]acetylcholine from the myenteric plexus of the small intestine (IC50: 0.7 nmol/l) with a similar potency at 3 and 10 Hz stimulation. An increase in the extracellular calcium concentration…