Search results for "isoprenaline"
showing 8 items of 48 documents
Adrenergic modulation of astroglial phospholipase D activity and cell proliferation.
1999
As phospholipase D (PLD) activation has been associated with mitogenic signalling in several cell types, we tested an association between adrenergic activation of PLD and cellular proliferation in primary cultures of rat cortical astrocytes. In 2-week old cultures, PLD activation by noradrenaline (EC50: 0.49 microM) was inhibited by prazosin, a specific antagonist at alpha1-adrenergic receptors (IC50: 0.23 microM). Adrenergic PLD activation was not affected by genistein, an inhibitor of tyrosine kinases, or by Ro 31-8220, an inhibitor of protein kinase C (PKC), but was dose-dependently depressed in the presence of brefeldin A (1-100 microg/ml), an inhibitor of ARF activation. In experiments…
Beta-adrenoceptor-mediated facilitation of endogenous noradrenaline release from rat isolated trachea.
1994
Overflow of endogenous noradrenaline from rat isolated trachea was evoked by electrical field stimulation (3 Hz, 540 pulses) in the presence of yohimbine, desipramine and tyrosine. Isoprenaline 100 nmol/l increased the evoked overflow of noradrenaline by about 65%. This effect was antagonized by propranolol (100 nmol/l) and the beta 2-selective adrenoceptor antagonist ICI 118,551 (100 nmol/l), but not by the beta 1-selective adrenoceptor antagonist CGP 20712 A (100 nmol/l). The beta 2-selective adrenoceptor agonist formoterol (1-100 nmol/l) also facilitated the evoked overflow of noradrenaline, but maximally by only about 25% at 10 nmol/l, i.e. formoterol behaved as a partial agonist at the…
The release of choline from phospholipids mediated by beta-adrenoceptor activation in isolated hearts.
1986
The resting efflux of choline into the perfusate (Tyrode's solution) of isolated hearts was equal to the rate, at which choline was liberated from phospholipid degradation (Lindmar et al. 1986). Infusion of isoprenaline (2 X 10(-7) mol/l), forskolin (1-3 X 10(-6) mol/l) or 3-isobutyl-1-methylxanthine (IBMX; 3 X 10(-4) mol/l) for 40 min markedly enhanced the efflux of choline. The increase was linear during the experimental period and, in the case of isoprenaline, was blocked by 3 X 10(-7) mol/l atenolol. In the guinea-pig heart, IBMX at a threshold concentration of 10(-4) mol/l shifted the concentration-response curve for the effect of forskolin on the efflux of choline to the left by one l…
Neuronal and extraneuronal uptake and efflux of catecholamines in the isolated rabbit heart
1974
1. Isolated rabbit hearts were perfused with (−)-noradrenaline, (−)-adrenaline and (±)-isoprenaline for various time periods (1–180 min) and then washed with an amine-free medium. The venous concentration of the amine was estimated fluorimetrically during the infusion and after its end, to study removal and efflux, respectively. 2. In untreated hearts and after pretreatment with reserpine the removal had a constant rate over 20–60 min. After pretreatment with pargyline to block monoamine oxidase (MAO), however, the removal of noradrenaline declined exponentially to zero. Inhibition of the neuronal uptake (desipramine) and chemical sympathectomy (6-hydroxydopamine) abolished the removal of n…
Beta-adrenoceptor stimulation enhances transmitter output from the rat phrenic nerve.
1988
Abstract 1. Neurally-evoked output of newly synthesized [3H]-acetylcholine from the rat phrenic nerve was measured in the absence of cholinesterase inhibitors. 2. Noradrenaline and isoprenaline enhanced neurally-evoked transmitter output markedly. Moreover, immediately after the application of noradrenaline the basal tritium efflux increased significantly. 3. Pretreatment with propranolol (0.1 mumol l-1) or atenolol (0.3 mumol l-1) completely prevented the stimulatory effect of noradrenaline and isoprenaline on evoked transmitter output. 4. The facilitatory effect of isoprenaline declined, when the exposure time was increased. This observation supports the assumption that beta-adrenoceptors…
Effect of cocaine and related drugs on the uptake of noradrenaline by heart and spleen
1961
Noradrenaline uptake by heart and spleen after intravenous infusion of noradrenaline was measured in the pithed rat. Cocaine, given before the infusion, inhibited the noradrenaline uptake in relation (a) to the dose administered and (b) to the amount of noradrenaline infused. There was an association between increase in the pressor response to a test dose of noradrenaline and inhibition of the uptake by the heart. Drugs related chemically to cocaine, such as alpha-cocaine, amethocaine, and atropine, did not alter the noradrenaline uptake or potentiate the blood pressure response to noradrenaline. The noradrenaline uptake by the heart was unchanged after dibenamine, but blocked by the dichlo…
Effects of dopamine in isolated rat colon strips.
2005
The aim of the present work is to investigate the effects of dopamine on isolated rat colon strips, and whether dopamine receptors are involved in these effects. Experiments on spontaneous motility and under potassium contraction were performed with dopamine and isoprenaline, both in the absence and presence of antagonists (distal colon strips, isotonic recording, Tyrode solution, 31 °C, 1 g of resting tension). At higher concentration (10–4mol/L), dopamine abolished spontaneous motility of the rat colon and this effect was not modified by antagonists. In isolated rat colon strips that were depolarized with potassium, dopamine produced concentration-dependent relaxation, without significant…
Isoprenaline and forskolin increase evoked vasopressin release from rat pituitary
1982
Isolated neurointermediate lobes of rat pituitaries were incubated in Krebs solution. The vasopressin release evoked by electrical stimulation (0.2 ms, 80 V, 15 Hz, 10 s trains at 10 s intervals for a total of 10 min) was completely inhibited by tetrodotoxin. Isoprenaline increased the evoked vasopressin release to a maximum of 60% (EC50 10 nM) and this effect was antagonized surmountably by propranolol. Forskolin increased the vasopressin release by 98%. These results suggest the presence within the neurohypophysis of a beta-adrenoceptor-linked adenylate cyclase facilitating vasopressin secretion.