Search results for "guinea"
showing 10 items of 412 documents
Release of [3H]acetylcholine from the isolated rat or guinea-pig trachea evoked by preganglionic nerve stimulation; a comparison with transmural stim…
1991
Basal and stimulated outflow of radioactive acetylcholine, phosphorylcholine and choline from rat and guinea-pig isolated tracheae were measured by reverse phase HPLC followed by liquid-scintillation-spectrometry. Tracheae were stimulated either by an electrical field (transmural stimulation) or by a local stimulation of the innervating parasympathetic nerves (preganglionic stimulation). Epithelium was removed in most experiments, as the epithelium inhibits acetylcholine release. The basal tritium efflux (1,600 dpm/3min) from rat isolated tracheae incubated with [3H]choline consisted of 56% [3H]phosphorylcholine and 38% [3H]choline. Preganglionic stimulation (15 Hz, 1,200 pulses) caused a 2…
Über die Wirkung von Phosphodiesterase-Hemmstoffen am Herzen / The Influence of Phosphodiesterase Blocking Agents on the Perfused Guinea Pig Heart
1969
Es wurde der Einflus von Phosphodiesterase-Hemmstoffen auf die Funktion und einige Parameter des Kohlenhydratstoffwechsels des Herzens untersucht, um weiteren Aufschlus uber den Zusammenhang zwischen cyclischem AMP und der Regulation dieser Funktionen zu gewinnen. Isolierte Meerschweinchenherzen wurden nach Langendokff bei 37° C mit carbogengesattigter Tyrodelosung perfundiert und konstant mit einer Frequenz von 180/min gereizt. Die Herzen wurden nach einem Kontrollvorlauf 5–20 min mit der pharmakonhaltigen Tyrodelosung durchstromt. Es wurde die Wirkung von Substanzen untersucht, die nach Senft u. Mitarb. [1] in den angegebenen Konzentrationen eine 50% Hemmung der PDE des Rinderherzens in v…
Tetrodotoxin slightly shortens action potential duration in ventricular but not in atrial heart muscle.
1988
Tetrodotoxin (TTX), at concentrations significantly decreasing maximal upstroke velocity (dV/dtmax) of the action potential, exerted variable effects on action potential duration (APD) in different myocardial preparations. APD was virtually unchanged by tetrodotoxin in the guinea pig atrium, but slightly shortened in the guinea pig ventricle at maximally effective concentrations. In the human ventricle, both dV/dtmax and APD were reduced in the same concentration range of TTX. These results suggest that a TTX-sensitive sodium current significantly contributes to the repolarization phase of the action potential in ventricular but not in atrial heart muscle.
The effect of tacrine on acetylcholine overflow in the heart
1990
Tacrine, 10(-6) M, enhanced the acetylcholine (ACh) overflow evoked in perfused chicken hearts by field stimulation (5 Hz, 1 min) from 183 to 346 pmol g-1 min-1. Increase to the same level were observed after pretreatment with diisopropylfluorophosphate (DFP) as well as after DFP plus 10(-6) M tacrine. Tacrine, 10(-5) M, caused further enhancement with or without DFP up to 851 pmol g-1 min-1. It was concluded that 10(-6) M tacrine enhanced the ACh overflow by choline esterase inhibition, whereas 10(-5) M tacrine caused, in addition, an increase of neuronal ACh release.
Sinusoidal endothelial liver cells in vitro release endothelin — Augmentation by transforming growth factorβ and Kupffer cell-conditioned media
1991
Endothelin is the most potent vasoconstrictor peptide known today. Using a radioimmunoassay for endothelin, we measured immunoreactive endothelin in culture media of guinea pig sinusoidal endothelial liver cells and human umbilical vein endothelial cells. A time-dependent release of immunoreactive endothelin by confluent sinusoidal endothelial liver cells in culture was found. Sinusoidal endothelial liver cells produced similar amounts of immunoreactive endothelin as umbilical vein endothelial cells, about 900 pg/microgram DNA per 24 h. In the presence of transforming growth factor beta a dose-dependent increase of immunoreactive endothelin release was measured. The maximal increase of 50% …
Bronchodilator and anti-inflammatory activities of SCA40: studies in human isolated bronchus, human eosinophils, and in the guinea-pig in vivo.
1998
There is currently interest in the use of inhibitors of cyclic nucleotide phosphodiesterases (PDE) as potential anti-asthma agents. In this study we examined the effects of SCA40 (6-bromo-8-methylaminoimidazol-[1,2-a] pyrazine-2-carbonitrile), a preferential inhibitor of PDE 3 also endowed with PDE 4 and 5 inhibitory activities, on isolated bronchus and eosinophil functions and in an animal model of asthma. SCA40 (1 nM-0.1 mM) produced concentration-dependent inhibition of spontaneous and stimulated tone of human isolated bronchus and reached a maximal relaxation similar to that of theophylline (3 mM). The potency (-log EC50 values) of SCA40 against spontaneous tone (6.52 +/- 0.10) was grea…
Mechanisms of C-reactive protein-induced blood-brain barrier disruption.
2009
Background and Purpose— Increased mortality after stroke is associated with brain edema formation and high plasma levels of the acute phase reactant C-reactive protein (CRP). The aim of this study was to examine whether CRP directly affects blood–brain barrier stability and to analyze the underlying signaling pathways. Methods— We used a cell coculture model of the blood–brain barrier and the guinea pig isolated whole brain preparation. Results— We could show that CRP at clinically relevant concentrations (10 to 20 μg/mL) causes a disruption of the blood–brain barrier in both approaches. The results of our study further demonstrate CRP-induced activation of surface Fcγ receptors CD16/32 fo…
Molecular anatomy of the neuro-immune connection.
1991
Light microscopic immunohistochemistry was employed to elucidate and compare the presence, distribution, and coexistence of various peptides, neuroendocrine markers and enzymes of the catecholamine pathway in nerves supplying lymphoid tissues in a variety of mammalian species. All lymphoid organs and tissues receive innervation by fibers containing dopamine-beta-hydroxylase and/or tyrosine hydroxylase, neural markers like protein gene product 9.5, synaptophysin and neurofilament and a varied spectrum of peptides. The prominent peptides were tachykinins (substance P, neurokinin A), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), and vasoactive intestinal polypeptide/peptide his…
Studies on the mechanism of PMN activation III. by lymphokines.
1983
The influence of a guinea pig lymphokine preparation on the oxidative metabolism of human and guinea pig granulocytes of various sources was investigated. A dose-dependent increase of the oxidative burst following lymphokine challenge was observed. It occurred in unstimulated guinea pig peripheral polymorphonuclear leukocytes (PMN) and in prestimulated PMN obtained from the peritoneal cavity after glycogen injection as well. The lymphokine effect on the oxidative metabolism is not species-restricted because the guinea pig lymphokine preparation elicits an oxidative burst in human PMN, too. The increase caused by lymphokines is nearly of the same order of magnitude as that obtained with zymo…
The influence of Ca2+ antagonists on the ciliary activity of the guinea pig trachea.
1990
The ciliary activity of the guinea pig tracheal respiratory epithelium was measured using a photoelectric device. Fourteen animals were administered 75 mg diltiazem/kg body weight 2 days, 1 day and 4 h prior to the investigation. Thirteen animals served as controls. In the pretreated group, the mean ciliary stroke frequency (13.4 +/- 3.0 Hz) was significantly lower (P = 0.02) than in the control group (16.6 +/- 3.7 Hz). The application of aerosolized 0.3 mmol/l nifedipine solution on the tracheal preparations of the control animals also significantly reduced the stroke frequency (P = 0.02). The ciliary activity never dropped beyond a frequency of about 8 Hz. The most probable interpretation…