In:
Journal of Applied Physiology, American Physiological Society, Vol. 90, No. 1 ( 2001-01-01), p. 248-260
Abstract:
We investigated the responses of systemic arterial pressure and vertebral sympathetic nerve activity to glutamate microinjections (0.1 M, 70 nl) in the dorsomedial (DM) and the rostral ventrolateral medulla (RVLM) before hypoxia and after reoxygenation (posthypoxia) after various degrees of hypoxia in anesthetized cats. Hypoxia was produced by ventilating 5% O 2 and 95% N 2 for different durations (hypoxia I-III). In intact cats, the glutamate-induced systemic arterial pressure and vertebral nerve activity responses of the DM were depressed after all degrees of hypoxia. Posthypoxic depression in the RVLM, however, was not observed until hypoxia II and III. Precollicular decerebration prevented depression in the RVLM, but, for the DM, it was effective only for hypoxia I. Baro- and chemoreceptor denervation abolished all posthypoxic depression in both the DM and the RVLM. Pressor responses to tyramine (100–400 μg/kg iv) remained unchanged after all degrees of hypoxia. These results suggest that the DM is more susceptible to hypoxia than the RVLM. The peripheral baro- and chemoreceptors and the suprapontine structures apparently play an important role in posthypoxic depression. Moreover, the depression is not due to the postganglionic norepinephrine depletion.
Type of Medium:
Online Resource
ISSN:
8750-7587
,
1522-1601
DOI:
10.1152/jappl.2001.90.1.248
Language:
English
Publisher:
American Physiological Society
Publication Date:
2001
detail.hit.zdb_id:
1404365-8
SSG:
12
SSG:
31
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