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  • 1
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    Clinical and experimental pharmacology and physiology 28 (2001), S. 0 
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. Previous reports indirectly implicate a neural mechanism for coronary constriction to centrally administered digitalis. However, autoregulatory changes in coronary resistance due to changes in arterial pressure may have influenced the interpretation of these studies.2. We tested directly the hypothesis that cardiac sympathetic innervation is responsible for coronary constriction to ouabain by examining the effects of ouabain (intravenous (i.v.) and intracerebroventricular (i.c.v.)) before and after bilateral stellate ganglionectomy.3. Cats were anaesthetized and instrumented for the measurement of heart rate, blood pressure and coronary blood flow velocity using an epicardial-attached suction Doppler probe. Animals were treated with atenolol and the effects of either i.v. or i.c.v. injections of ouabain were examined.4. In seven cats treated with atenolol, i.v. ouabain (0.11 mg/kg) produced maximal increases in arterial pressure and coronary vascular resistance index (CVRI) of 66 ± 7 mmHg and 37 ± 9%, respectively. Following bilateral stellate ganglionectomy (n = 7), ouabain produced similar increases in arterial pressure (70 ± 9 mmHg) and CVRI (39 ± 7%). A higher dose of i.v. ouabain (1.1 mg/kg) produced maximal increases in arterial pressure (115 ± 4 mmHg) and coronary resistance (86 ± 14%) in intact cats (n = 6) that were similar to responses seen in cats in which stellate ganglionectomy had been performed (n = 6; arterial pressure 104 ± 13 mmHg; coronary resistance 114 ± 6%). The increases in coronary resistance to ouabain at both doses were significantly greater than increases in coronary resistance to passive elevation of arterial pressure during aortic constriction. Thus, autoregulation does not explain fully the coronary constriction to ouabain.5. To further examine a central mechanism, i.c.v. perfusion with 0.3 mmol/L ouabain was performed in six cats, resulting in increases in arterial pressure (122 ± 7 mmHg) and coronary resistance (58 ± 14%). Similar increases in arterial pressure (117 ± 16%) and coronary resistance (84 ± 20%) were seen in separate studies (n = 6) following stellate ganglionectomy.6. These results indicate that coronary constriction to ouabain does not require intact cardiac sympathetic innervation, but probably involves a direct or humorally mediated effect.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 231 (1971), S. 263-265 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Effect of reduced renal pressure on adrenergic responses during infusion of angiotensin. Hind paw perfusion pressure (PP) and systemic blood pressure (AP) are calibrated in mm Hg. The left hand portion shows responses to intra-arterial noradrenaline (50, 100, 200 ng) and sympathetic nerve ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 69 (1997), S. 407-417 
    ISSN: 1432-1246
    Keywords: Key words Olfaction ; Irritation ; Response bias ; Health symptoms ; Acetone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective: Responses to volatile chemicals are often subjective and variable, both over time and across individuals. Although variability can derive from differences in individual olfactory sensitivity, the response to a chemical stimulus is also influenced by the complex environment surrounding the exposure, which can include the perceiver’s cognitive state. To explore the role of cognitive bias in chemical exposures, we evaluated whether information about the consequences of exposure to acetone could influence ratings of odor and irritation during exposure and/or the frequency or intensity of reported health symptoms following exposure. Methods: Ninety adults (mean age 33.7, range 25–64) with no history of occupational exposure to solvents, were exposed to 800 ppm acetone in a chamber for 20 min. To control for non-specific responses to the odor of acetone, the subjects were also exposed for 20 min to 200 ppm phenylethyl alcohol (PEA), a nonirritant volatile chemical that produces a distinct odor but does not elicit irritation in the vapor phase. Subjects were assigned to one of three groups (n=30/group); each group was given either a positive, negative or neutral bias towards the consequences of exposure to the chemicals in the study. During exposure, subjects rated the intensity of odor and irritation; following exposure, they completed symptom questionnaires. Results: During the 20-min exposure to acetone, the positive bias group exhibited the most adaptation to its odor and the lowest perceived irritation; following exposure they reported the fewest health symptoms. In contrast, the negative bias group rated higher levels of odor intensity and, on average, reported the most overall irritation; following exposure they reported significantly more health symptoms than the other groups. None of the demographic variables studied (e.g., age, gender, race, smoking status) were predictive of the response to odor or irritation. The perceived irritancy of acetone was well predicted by a linear combination of the perceived odor of acetone and the perceived irritation from PEA (the nonirritant), r 2=0.73. Conclusions: The results provide strong evidence that both the perceived odor and cognitive expectations about a chemical can significantly affect how individuals respond to it. Moreover, because naive control subjects appear to exhibit extreme variation in their cognitive evaluations of chemical effects, there may be limited value in using non-exposed controls to assess the irritancy of chemicals for worker populations.
    Type of Medium: Electronic Resource
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