0000000000311991
AUTHOR
I. T. Bognar
Inhibition by interleukin-1 beta of noradrenaline release in rat spleen: involvement of lymphocytes, NO and opioid receptors.
Effects of indomethacin, N omega-nitro-L-arginine (NNA) and naloxone, and of pretreatment with cyclophosphamide (CY), on the interleukin (IL)-1 beta induced inhibition of exocytotic noradrenaline release were investigated in the isolated, vascularly perfused spleen of the rat. Neurotransmitter release was evoked by perivascular electrical stimulation (4 Hz) and the overflow of endogenous noradrenaline was determined by HPLC with electrochemical detection. Perfusion of the spleen with Tyrode's solution containing IL-1 beta (100 pg/ml) for 90 min caused an inhibition of the stimulation-evoked noradrenaline overflow which persisted for at least 20 min after washout of the IL. The evoked overfl…
A muscarinic receptor different from the M1, M2, M3 and M4 subtypes mediates the contraction of the rabbit iris sphincter
In order to analyse the subtype of muscarinic receptors involved in the methacholine-induced contraction of the rabbit iris sphincter we have determined equilibrium dissociation constants (KB) of various antagonists in the sphincter muscle. The values were compared with those observed at M1 (rabbit vas deferens), M2 (heteroreceptors in rat iris) and M3 receptors (guinea-pig ileum), or at the muscarinic receptors in the guinea-pig uterus. The methacholine-induced contraction of the uterus from immature guinea-pigs was competitively antagonized by pirenzepine (6.64, -log KB), 4-DAMP (8.39), hexahydrodifenidol (HHD; 7.00 for the (R)- and 5.40 for the (S)-enantiomer), p-fluoro-hexahydrosiladife…
Muscarine receptor types mediating autoinhibition of acetylcholine release and sphincter contraction in the guinea-pig iris.
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…
Effects of human recombinant interleukins on stimulation-evoked noradrenaline overflow from the rat perfused spleen
Experiments were carried out in the isolated spleen of the rat to study in a lymphoid organ the influence of interleukins (ILs) on noradrenaline release. Spleens were perfused with Tyrode's solution and the overflow of endogenous noradrenaline was determined by HPLC with electrochemical detection. Perivascular electrical stimulation (4 or 10 Hz, 20-28 mA, 2 min) caused an increase in noradrenaline overflow and in perfusion pressure, both of which were markedly reduced by perfusion with Ca(2+)-free solution, abolished by tetrodotoxin, unaffected by hexamethonium, and subject to alpha 2-adrenoceptor- and muscarinic receptor-mediated modulation as shown by the effects of rauwolscine and methac…
Different muscarinic receptors mediate autoinhibition of acetylcholine release and vagally-induced vasoconstriction in the rat isolated perfused heart
Experiments were carried out on rat isolated perfused hearts with both vagus nerves attached. The acetylcholine stores were labelled with [14C]-choline. The effects of muscarinic receptor antagonists on the [14C]-overflow and increase in perfusion pressure evoked by vagus nerve stimulation (10 Hz, 4-10 mA) were studied in order to determine the muscarinic receptor type involved in autoinhibition of acetylcholine release and vagally-induced vasoconstriction in the rat heart. Stimulation of the vagus nerves (1200 pulses) caused an increase in [14C]-overflow and in perfusion pressure which was significantly reduced by hexamethonium 500 mumol/l and abolished by tetrodotoxin 0.3 mumol/l or perfu…