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Activation of the nucleus of the solitary tract (nTS) due to chemoreflex stimulation with acute hypoxia (AH) is independent of hypoxia‐induced changes in arterial blood pressure (ABP)
Author(s) -
King T Luise,
Clark Catharine G,
Heesch Cheryl M,
Kline David D,
Hasser Eileen M
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1076.14
Subject(s) - hypoxia (environmental) , stimulation , blood pressure , solitary tract , medicine , anesthesia , chemistry , cardiology , oxygen , central nervous system , organic chemistry
Afferent baroreflex and chemoreflex information is integrated in the nTS. AH activates chemoafferents and increases nTS neuronal activation, but also alters ABP. To evaluate the influence of changes in ABP on nTS neuronal activation due to AH, we stimulated the arterial chemoreflex while maintaining ABP constant. ABP was monitored in conscious rats (using radiotelemetry) during 2 hrs of Normoxia (N: 21% O2, n=4), AH (10% O2, n=5) or AH and phenylephrine infusion (0.6mg/mL: 0.1–0.5mL/hr) to maintain a constant ABP (AH+PE, n=4). Rats were perfused and brainstems processed for examination of Fos‐immunoreactivity (IR) as an index of nTS activation and tyrosine hydroxylase (TH)‐IR to identify catecholaminergic neurons. ABP decreased 17±4 mmHg within 15 min and remained low during AH. In AH+PE rats, ABP was maintained constant, similar to N rats. Compared to N (16±5 cells), hypoxia increased the number of Fos‐IR nTS neurons whether ABP varied (AH: 184±9) or was held constant (AH+PE: 176±6). Also, the number of Fos and TH‐IR colabeled nTS cells was similar in AH groups. Fos activation was greatest in the medial and dorsolateral nTS in both AH groups and there was no difference in subregional or caudal‐rostral distribution of Fos‐IR between AH groups. Data suggest that decreased ABP during hypoxia does not contribute substantially to nTS neuronal activation due to chemoreflex stimulation. HL55306, 85108, 98602.