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  • 1
    Electronic Resource
    Electronic Resource
    Does the xanthine-xanthine oxidase system alter contractile behaviour of vascular smooth muscle? (1987)
    Springer
    Pflügers Archiv 408 (1987), S. 204-206 
    Details
    ISSN: 1432-2013
    Keywords: xanthine oxidase ; ammonium ions ; vascular smooth muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Since xanthine oxidase (XOD) preparations are usually applied as crystalline suspensions in ammonium sulphate solution, we studied separately the contractile responses of excised rabbit carotid arteries to the free radical generating system of xanthine-XOD and ammonium ions. Using dialyzed XOD (0.1–0.2 U/ml) the contractile pattenr of the xanthine-XOD system was characterized by initial contraction followed by relaxation. Identical contractile behaviour was observed when xanthine was omitted from that system. These contractile responses were indistinguishable from those obtained with ammonium sulphate (10–20 mM). The threshold concentration of ammonium sulphate for inducing contraction was 1–2 mM. Both Ca++-free solution and verapamil only slightly inhibited the contractions produced by XOD and ammonium sulphate. No contractile effect was observed with dialyzed XOD. We conclude that the contractile effects of the xanthine-XOD system on vascular smooth muscle are due to simultaneously applied ammonium ions, and our findings emphasize the need for further purification of XOD preparations when investigating their effects on smooth muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581353
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  • 2
    Electronic Resource
    Electronic Resource
    Cigarette smoking, blood lipids, and baroreceptor-modulated nociception (1993)
    Springer
    Psychopharmacology 110 (1993), S. 337-341 
    Details
    ISSN: 1432-2072
    Keywords: Pain ; Baroreceptor stimulation ; PRES ; Smoking ; Nicotine ; Blood lipid levels ; Cholesterol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Activation of arterial blood pressure has been shown to influence higher central nervous activity. In animals, induction of sleep-like states and increases of seizure and pain thresholds in response to baroreceptor stimulation have been reported. In certain human groups, mechanical stimulation of the carotid baroreceptors also increases pain thresholds. The present paper examines the hypothesis that smokers show baroreceptor dependent antinociception as compared to non-smokers. It is speculated that one effect which rewards smoking is the nicotine induced phasic blood pressure increase which leads to baroreceptor stimulation and dampens pain perception. One hundred and twenty subjects were investigated using a recently developed mechanical baroreceptor stimulation technique and an electrical pain stimulus. The group of heavy smokers showed the predicted effect: their pain thresholds were enhanced during conditions of increased baroreceptor activity as compared to the control condition. The group of medium, light and non-smokers, however, did not show this effect. Neither blood lipid levels nor diastolic or systolic blood pressure paralleled the group differences on baroreceptor dependent antinociception. In heavy smokers, the nicotine induced phasic blood pressure increase might have baroreceptor dependent pain dampening effects, which might be among the reinforcing qualities of smoking.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02251290
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Vascular contractile function following experimental excimer laser angioplasty (1995)
    Springer
    Lasers in medical science 10 (1995), S. 25-30 
    Details
    ISSN: 1435-604X
    Keywords: Laser angioplasty ; Vasoconstriction ; Excimer ; Contractile function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The aim of this study was to determine the vasomotor response to in vivo excimer laser irradiation with regard to laser-induced tissue effects. Transfemoral excimer laser angioplasty was performed in the right carotid artery of 11 New Zealand white rabbits. In four additional rabbits (sham group), the procedure was performed without the application of laser energy. Angiography documented vessel dissection in five laser-treated animals. Perforation occurred in one animal. Rings of the treated artery and controls of the contralateral artery were investigated in a contraction chamber. The passive stress-strain relation (PSS) and the maximum contraction force (MCF) after stimulation with noradrenaline, serotonin and potassium chloride were determined. The treated vessels had a higher PSS than the control (p=0.05). The MCF was lower in the treated vessels (p〈0.05). The contraction force of the sham-operated vessels was higher, although statistically not significant, compared to the laser-irradiated segments. In a subset analysis, performed to compare vessels with moderate and severe trauma, MCF was significantly reduced in vessels with severe laser-induced injury. Experimental in vivo excimer laser angioplasty in this model resulted in heterogeneous structural changes, including dissections and perforation. Post-mortem assessment of vasomotor response showed no significant difference between laser-treated and sham-operated animals. However, the contractile function of the target vessel seems to be reduced following extensive laser-induced vessel injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02133160
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  • 4
    Electronic Resource
    Electronic Resource
    Ca2+ entry and vasoconstriction during osmotic swelling of vascular smooth muscle cells (1995)
    Springer
    Pflügers Archiv 431 (1995), S. 253-258 
    Details
    ISSN: 1432-2013
    Keywords: Cell volume ; Smooth muscle cells ; Cell membrane potential ; Intracellular Ca2+ concentration ; Ca2+ channel blockers ; Vasoconstriction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Exposure of aortic strips from guinea-pigs to hypotonic extracellular fluid is followed by marked vasoconstriction, which is inhibited by D-600 (3 μM), a blocker of voltage-sensitive Ca2+ channels. Conventional electrophysiology, patch-clamp studies, pH determination with 2′, 7′ bis(2-carboxyethyl)-5, 6-carboxyfluorescein (BCECF) and Ca2+ measurements with Fura-2 have been performed on smooth muscle cells cultured either from rat or human aorta to further elucidate the underlying mechanisms. Exposure of the cells to a 25% hypotonic extracellular fluid leads to a rapid and fully reversible depolarization, paralleled by an increase of the selectivity and conductance of the cell membrane to Cl−, an acidification of the cytoplasm and an increase of intracellular Ca2+ concentration ([Ca2+]i). The latter is inhibited by the Ca2+ channel blocker D-600 (1–3 μM). It is concluded that osmotic cell swelling leads to the activation of an anion channel. The subsequent depolarization of the cell membrane activates voltage-sensitive Ca2+ channels which increases [Ca2+]i, thus stimulating the contraction of vascular smooth muscle cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410198
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  • 5
    Electronic Resource
    Electronic Resource
    Luminol-enhanced chemiluminescence after reaction of hydroperoxides with opsonized zymosan (1995)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 10 (1995), S. 71-76 
    Details
    ISSN: 0884-3996
    Keywords: Oxygen free radicals ; superoxide anion ; hydroperoxides ; luminol-enhanced chemiluminescence ; opsonized zymosan ; radical scavengers ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Luminol-enhanced chemiluminescence (LEC) is very sensitive in detecting free radicals but relatively insensitive for hydroperoxides (hydrogen peroxide, tert-butyl hydroperoxide). However, in the presence of opsonized zymosan (often used for stimulation of phagocytic cells) hydroperoxides also induce LEC, suggesting that free radicals are produced under these conditions. Therefore careful interpretation with respect to the nature of the reactive species is necessary when LEC is used for characterization of zymosan-induced phagocytosis. We studied the properties of zymosan-induced LEC under different test conditions and with various inhibitors. Typical radical scavengers, e.g. nordihydroguaiaretic acid and superoxide dismutase, are strong inhibitors, indicating the importance of the superoxide anion. This system is useful for drug testing with respect to antioxidative or radical scavenging activity.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170100202
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