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This Article Full Text Full Text (PDF) All Versions of this Article: 292/5/R1862    most recent 00325.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Ahlgren, J. Articles by Hayward, L. F. Search for Related Content PubMed PubMed Citation Articles by Ahlgren, J. Articles by Hayward, L. F.

NEUROHUMORAL CONTROL OF CARDIOVASCULAR FUNCTION

Hemodynamic responses and c-Fos changes associated with hypotensive hemorrhage: standardizing a protocol for severe hemorrhage in conscious rats

Department of Physiological Sciences, University of Florida, Gainesville, Florida

Submitted 15 May 2006 ; accepted in final form 4 January 2007

The central mechanisms underlying the transition from compensation to decompensation during severe hemorrhage (HEM) are poorly understood. Furthermore, a lack of consistency in HEM protocols exists in the current literature. This study assessed the cardiovascular response and Fos-like immunoreactivity (FLI) in specific brain regions following severe HEM at three rates (2, 1, or 0.5 ml·kg^–1·min^–1) in conscious rats. Heart rate (HR) and arterial pressure were recorded during the withdrawal of 30% of total blood volume (TBV). Data from animals hemorrhaged at the fast (F-HEM, n = 6), intermediate (I-HEM, n = 7), or slow (S-HEM, n = 7) rates were compared with saline (SAL, n = 5) and hypotensive (hydrazaline-induced, HYDRAZ, n = 5) controls. All HEM rates produced similar degrees of hypotension at the time of 30% TBV withdrawal. All HEM rates also produced bradycardia, but the change in HR was only significant in the F-HEM and I-HEM groups. Associated with I-HEM and F-HEM, but not HYDRAZ treatment were significant increases in FLI in the caudal ventrolateral periaqueductal gray (PAG), the central lateral nucleus of the rostral parabrachial nucleus, and locus coeruleus compared with SAL treatment. I-HEM also induced significant increases in FLI in the dorsomedial PAG, A7 region, and the cuneiform nucleus compared with SAL. S-HEM did not induce any significant change in FLI. Our results suggest that HEM at a rate of 1 ml·kg^–1·min^–1 may be most useful for investigating the potential role of the rostral brainstem regions in mediating hemorrhagic decompensation in conscious rats.

total blood volume; hydrazaline