Search results for "NEP"

2018

Abstract. Air traffic affects cloudiness, and thus climate, by emitting exhaust gases and particles. The study of the evolution of contrail properties is very challenging due to the complex interplay of vortex dynamics and the atmospheric environment (e.g. temperature, supersaturation). Despite substantial progress in recent years, the optical, microphysical, and macrophysical properties of contrails and ambient cirrus during contrail formation and subsequent ageing are still subject to large uncertainties due to instrumental and observational limitations and the large number of variables influencing the contrail life cycle. In this study, various contrail cases corresponding to different a…

Porous aerosol in degassing plumes of Mt. Etna and Mt. Stromboli

2016

Abstract. Aerosols of the volcanic degassing plumes from Mt. Etna and Mt. Stromboli were probed with in situ instruments on board the Deutsches Zentrum für Luft- und Raumfahrt research aircraft Falcon during the contrail, volcano, and cirrus experiment CONCERT in September 2011. Aerosol properties were analyzed using angular scattering intensities and particle size distributions simultaneously measured with the Polar Nephelometer and the Forward Scattering Spectrometer probes (FSSP series 100 and 300), respectively. Aerosols of degassing plumes are characterized by low values of the asymmetry parameter (between 0.6 and 0.75); the effective diameter was within the range of 1.5–2.8 µm and the…

Autoinhibition of nicotinic release of noradrenaline from postganglionic sympathetic nerves

1970

1. The effects of nicotine, DMPP (1,1-dimethylphenylpiperazine) and acetylcholine (plus atropine) on the isolated rabbit heart were investigated. Heart rate, amplitude of contraction, coronary flow and output of noradrenaline into the perfusate were recorded. Noradrenaline was estimated fluorimetrically. 2. All nicotinic drugs evoked a dose-dependent output of noradrenaline and increased the rate and the amplitude of contraction. Increases of heart rate in response to nicotine and DMPP and increases of amplitude of contraction in response to all nicotinic drugs were clearly related to the output of noradrenaline. 3. The dose-response curves of the noradrenaline output evoked by nicotine, DM…

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…

Muscarinic inhibition of [3H]-noradrenaline release on rabbit iris in vitro: effects of stimulation conditions on intrinsic activity of methacholine …

1988

1. Rabbit isolated irides were loaded with [3H]-noradrenaline and superfused with Tyrode solution. The inhibition by the muscarinic agonists (+/-)-methacholine and pilocarpine of the [3H]-noradrenaline overflow into the superfusate evoked by field stimulation (pulses of 1 ms duration, 75 mA) was measured as an index of activation of presynaptic muscarinic receptors. 2. The fractional rate of release per pulse during the first stimulation period (S1) was low with 360 pulses at 3 Hz, intermediate with 360 pulses at 10 Hz and high with 1200 pulses at 10 Hz. Upon repetitive stimulation (7 periods at 20 min intervals), the fractional rates of release per pulse during S7 no longer differed, sugge…

Muscarinic inhibition of potassium-induced noradrenaline release and its dependence on the calcium concentration.

1975

1. Noradrenaline release from the isolated rabbit heart was evoked by perfusion with a medium containing 135 mM potassium and 17 mM sodium ions (high K+-low Na+). 2. The noradrenaline output in response to high K+-low Na+ was dose-dependently decreased by methacholine (0.625-320 muM) and this effect was reserved by atropine 1.44 mM. 3. Lowering the calcium concentration of high K+-low Na+ from 1.8-0.1125 mM decreased the noradrenaline output by 85%. The effect of methacholine, expressed as % inhibition of noradrenaline release, was potentiated by lowering of the calcium concentration. 4. Both at normal and lowered calcium concentrations the inhibitory action of methacholine was larger from …

Effects of several muscarinic agonists on cardiac performance and the release of noradrenaline from sympathetic nerves of the perfused rabbit heart

1972

Summary 1 The effects of several muscarinic agonists on atrial tension development, ventricular rate and noradrenaline release from terminal sympathetic fibres evoked by electrical nerve stimulation (SNS) and 1,1-dimethyl-4-phenylpiperazinium (DMPP) were measured in isolated perfused rabbit hearts. 2 Hexamethonium, in a concentration which almost abolished the release of noradrenaline by DMPP, had no effect on the release produced by SNS, confirming that the stimulation was postganglionic. 3 The order of potency for inhibition of atrial tension development was N-methyl-1,2,5,6, tetrahydro-nicotinic acid prop-2-yne ester (MH-1)>oxotremorine > acetylcholine > methacholine > carbachol > furtre…

Storage and release of false transmitters after infusion of (+)- and (?)-?-methyldopamine

1971

Rabbits were given an infusion of 10 mg/kg (−)- or 30 mg/kg (+)-α-methyldopamine and killed after 135 min. The noradrenaline content of the heart was decreased to 26±5 and 34±2%, respectively, of the control value. After infusion of the (+)-isomer the missing noradrenaline was replaced by (−)-α-methylnoradrenaline. Electrical stimulation of the sympathetic nerves or infusion of acetylcholine plus atropine caused an output of noradrenaline and (−)-α-methylnoradrenaline from the isolated heart. The two amines were released in the same proportion as they were stored in the heart and the total output of both amines equalled the output of noradrenaline from control hearts. Nerve stimulation caus…

Short- and long-latency muscarinic inhibition of noradrenaline release from rabbit atria induced by vagal stimulation.

1988

1. The influence of the time interval between vagal and sympathetic nerve stimuli on the magnitude of muscarinic inhibition of noradrenaline release was studied in the isolated perfused rabbit atria preparation. The transmitter stores were labelled with [14C]choline and [3H]noradrenaline. 2. The right cardiac postganglionic sympathetic nerves were stimulated at 3 Hz for 3 min three times at intervals of 10 min. The [3H]noradrenaline outflow evoked by the second stimulation equalled the averaged means of the log values of amine outflows evoked by the first and third stimulations. 3. During the second sympathetic stimulation the right vagus nerve was stimulated (3 Hz, 3 min) in such a way tha…

A muscarinic inhibition of the noradrenaline release evoked by postganglionic sympathetic nerve stimulation

1969

1. The noradrenaline output from isolated rabbit hearts perfused with Tyrode solution was estimated fluorimetrically. The postganglionic sympathetic nerves of the heart were stimulated (10 shocks/sec; 1 msec) for three 1 min periods with intervals of 10 min. 2. The noradrenaline output evoked by 3 consecutive stimulation periods decreased exponentially. 3. Acetylcholine (10−9–10−6 g/ml) administered continuously one min before to one min after the second stimulation caused a dose-dependent reduction of the noradrenaline output evoked by the second stimulation to as low as 19% of the normal value. Acetylcholine in the concentrations applied did not cause a noradrenaline output by itself. 4. …