Haemophilus influenzae type b impairment of pial vessel autoregulation in rats

Ivor D. Berkowitz, William R. Hayden, Richard J. Traystman, M. Douglas Jones

Research output: Contribution to journalArticlepeer-review

Abstract

To examine the mechanisms of autoregula-tory impairment in meningitis, we studied the effects of Haemophilus influenzae type b (Hib) on pial vessels during hemorrhagic hypotension in rats, using a cranial window technique. We prepared cranial windows in barbiturate-anesthetized, mechanically ventilated rats. Artificial cerebrospinal fluid or 10s Hib in cerebrospinal fluid (n = 7 each group) was suffused over the pial surface. Pial arteriolar diameter was measured hourly for 4 h. Autoregulation was assessed as the ability of pial arterioles to dilate in response to graded hemorrhagic hypotension at 2 and 4 h. Pial arterioles exposed to Hib dilated progressively to 149 ± 27% of baseline at 4 h. Vessel diameter in the Hib group was significantly greater than in the control group beginning at 2 h. Autoregulation was progressively impaired in Hib-exposed rats compared with control rats [-5.85 ± 1.38 versus -8.02 ± 2.02 and -3.82 ± 1.57 versus -8.53 ± 1.72% dilation/kPa fall in mean arterial blood pressure at 2 and 4 h, respectively (p < 0.05)]. These data suggest that autoregulation is impaired in pial arterioles exposed to Hib because involved vessels have a finite dilatory capacity and are close to maximal dilation before hypotensive challenge.

Original languageEnglish (US)
Pages (from-to)48-51
Number of pages4
JournalPediatric research
Volume33
Issue number1
DOIs
StatePublished - Jan 1993

ASJC Scopus subject areas

  • Pediatrics, Perinatology, and Child Health

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