Fetal sheep adrenal blood flow responses to hypoxemia after splanchnicotomy using fluorescent microspheres

Lynn F. Buchwalder, Michelle Lin, Thomas J. Mcdonald, Peter W. Nathanielsz

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Adrenal gland blood flow (ABF) increases during hypoxemia in fetal sheep, but regulation of ABF is poorly understood. The purpose of this study was to determine the effects of splanchnic nerve section on fetal ABF responses to hypoxemia using the fluorescent microsphere (FM) technique. At 125 days of gestation, 14 unanesthetized fetal sheep [bilateral splanchnicotomy (Splx, n = 6) and control (Cont, n = 8)] were injected with FM before and at 60 min of N2-induced hypoxemia (~40% decrease in fetal arterial Po(2)). Adrenal tissue and reference blood samples were digested and filtered, and FM dye was extracted for spectrometer analysis. Baseline whole, medullary, and cortical ABF for the Cont group were similar to published values using radioactive microspheres and did not differ from Splx values. Hypoxemia increased whole, medullary, and cortical ABF (mean ± SE) from baseline for the Cont group by 281 ± 35,258 ± 31, and 496 ± 81% (P < 0.05). The increase for the Splx group was attenuated compared with the Cont group (P < 0.05) for whole and medullary ABF (139 ± 27 and 43 ± 27%) but not cortical ABF (326 ± 91%). We conclude that 1) the FM technique is valid for measuring fetal ABF and 2) in fetal sheep the splanchnic nerve is not necessary to maintain basal ABF but plays an important role in regulating the hypoxemia-induced increase in ABF through the medullary, but not cortical, ABF response.

Original languageEnglish (US)
Pages (from-to)82-89
Number of pages8
JournalJournal of applied physiology
Volume84
Issue number1
DOIs
StatePublished - Jan 1998

Keywords

  • Late gestation
  • Nonradioactive
  • Regional blood flow
  • Splanchnic nerve section

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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