Search results for "epinephrine"
showing 10 items of 288 documents
The Effects of Cold Exposure on Leukocytes, Hormones and Cytokines during Acute Exercise in Humans
2014
The purpose of the study was to examine the effects of exercise on total leukocyte count and subsets, as well as hormone and cytokine responses in a thermoneutral and cold environment, with and without an individualized pre-cooling protocol inducing low-intensity shivering. Nine healthy young men participated in six experimental trials wearing shorts and t-shirts. Participants exercised for 60 min on a treadmill at low (LOW: 50% of peak VO2) and moderate (MOD: 70% VO2peak) exercise intensities in a climatic chamber set at 22°C (NT), and in 0°C (COLD) with and without a pre-exercise low-intensity shivering protocol (SHIV). Core and skin temperature, heart rate and oxygen consumption were col…
Nicotinic drugs and postganglionic sympathetic transmission
1970
1. Isolated rabbit hearts with the sympathetic nerves attached were perfused with Tyrode solution. The noradrenaline output into the perfusate was measured fluorimetrioally. 2. When the niootinic autoinhibition produced by infusions of nicotine, DMPP, or acetylcholine (in the presence of atropine) was fully developed, the output of noradrenaline evoked by electrical stimulation of the postganglionic sympathetic nerves was not depressed. 3. Acetylcholine in the presence of atropine produced a transitory facilitation of the noradrenaline output evoked by sympathetic nerve stimulation. 4. Prolonged infusion of DMPP caused an adrenergic neurone block which was not observed after nicotine, or ac…
Role of Ca2+-Activated K+ Channels on Adrenergic Responses of Human Saphenous Vein
2006
Background We studied the participation of K + channels on the adrenergic responses in human saphenous veins as well as the intervention of dihydropyridine-sensitive Ca 2+ channels on modulation of adrenergic responses by K + channels blockade. Methods Saphenous vein rings were obtained from 40 patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension. Results Iberiotoxin (10 −7 mol/L), an inhibitor of large conductance Ca 2+ -activated K + channels, and charybdotoxin (10 −7 mol/L), an inhibitor of both large and intermediate conductance Ca 2+ -activated K + channels, enhanced the contractions elicited by elec…
Demonstration of action-potential-producing cells in the rat pineal gland in vitro and their regulation by norepinephrine and nitric oxide
1998
There is evidence that sympathetically innervated mammalian pineal glands contain cells that exhibit action potentials. It is unknown whether ex vivo pineal glands deprived of their nervous input are still capable of firing. In the present study, multiple-unit recordings from rat pineals revealed spontaneously active cell clusters with a mean firing frequency of 1.5 +/- 0.3 Hz which could be abolished by tedrodotoxin. Regularly firing clusters showed no inherent periodicity in the minute range, whereas rhythmical clusters with periodically repeated bursts had period lengths of 12.6 min (day) and 9.5 min (night). Superfusion of norepinephrine reduced the firing frequency of both cluster type…
Effects of acute and chronic maprotiline administration on inhibitory avoidance in male mice
2000
The effects of acute and chronic administration of maprotiline (5, 10 or 20 mg/kg, intraperitoneally) were assessed on inhibitory avoidance in male mice. Acute administration of maprotiline before training did not effect training phase latencies, but impaired performance (i.e. produced shorter latencies) in the test at doses of 5 and 20 mg/kg. When given after training, the drug did not modify test latencies at any of the doses used. Chronic administration for 21 days (interrupted 24 h before training) also shortened latencies in the test but not in training. An experiment on the acute effects of maprotiline on analgesia (determination of flinch and jump thresholds for increasing electric f…
An intrinsic neuronal-like network in the rat pineal gland
1999
Recent studies have shown that in rat pineal glands kept in vitro action potential-producing cell clusters are demonstrable. To test whether the clusters interact, multiple-unit recordings were carried out simultaneously from different clusters, with or without electrical stimulation. Clusters with rhythmic burst activity exhibit highly synchronized firing and electrical stimulation of one cluster elicits an immediate response in another one, apparently involving synapses but not gap junctions. It is hypothesized that the interacting clusters form a network. As the firing is affected by norepinephrine, acetylcholine and Ca2+, the network may monitor the interstitial concentrations of these …
Characterization of the prejunctional muscarinic receptors mediating inhibition of evoked release of endogenous noradrenaline in rabbit isolated vas …
1994
The aim of the present study was to characterize the prejunctional modulation of evoked release of endogenous noradrenaline in rabbit vas deferens by the use of muscarinic receptor agonists and subtype-preferring antagonists. Vasa deferentia of the rabbit were stimulated electrically by trains of 120 pulses delivered at 4 Hz or trains of 30 pulses at 1 Hz. The inhibition by muscarinic agonists of the stimulation-evoked overflow of endogenous noradrenaline in the absence and presence of antagonists was used to determine affinity constants for antagonists. These values were compared with those observed at putative M1 receptors inhibiting neurogenic twitch contractions in the rabbit vas defere…
Noradrenaline depleting and blood pressure lowering activity of threo-corbadrine
1968
Abstract Threo-corbadrine caused a long-lasting depletion of noradrenaline in the heart and in mesenteric vessels and lowered the blood pressure of normal and renal hypertensive rats. It is suggested that threo-cobadrine decreases vascular tone by acting peripherally as a substitute adrenergic transmitter.
Neurosteroid modulation of the presynaptic NMDA receptors regulating hippocampal noradrenaline release in normal rats and those exposed prenatally to…
2003
Abstract Prenatal exposure to diazepam (DZ), a positive allosteric modulator of the γ-aminobutyric acidA (GABAA) receptor complex, exerts profound effects that become more evident during puberty and in many cases are sex-specific, suggesting that such exposure interferes with the activity of steroid hormones. Apart from their well known effects on the genome, the reduced metabolites of many steroid hormones also interact directly with membrane receptors, including those for N-methyl- d -aspartate (NMDA). In this study, we compared the effects of several neurosteroids on NMDA receptors from normal rats and those exposed in utero to DZ (1.25 mg/kg per day) from the 14th through the 20th day o…
Selective action of two aporphines at alpha 1-adrenoceptors and potential-operated Ca2+ channels.
1993
Abstract Contractions evoked by noradrenaline (1 μM) or a depolarizing solution of 60 mM KCI were concentration dependently depressed by the aporphine alkaloids (S)-boldine and (R)-apomorphine in rataorta. Both drugs had a greater inhibitory potency on the contraction elicited by noradrenaline. Dose-response curves for noradrenaline were shifted to the right in presence of (S)-boldine. (R)-Apomorphine acted by a complex mechanism at α 1 -adrenoceptors and its inhibitory effects was irreversible. The conformational features of these alkaloids may explain their different behaviour at α 1 -adrenoceptors. In Ca 2+ -free solution, the alkaloids inhibited the contraction evoked by noradrenaline b…