Effect of alpha adrenergic blockade on brain blood flow and ventilation during hypoxia in newborn piglets

C. Suguihara, Eduardo Bancalari, D. Hehre, H. Osiovich

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The influence of cardiovascular changes on ventilation has been demonstrated in adult animals and humans (Jones, French, Weissman and Wasserman, 1981; Wasserman, Whipp and Castagna 1974). It has been suggested that neonatal hypoxic ventilatory depression may be related to some of the hemodynamic changes that occur during hypoxia (Brown and Lawson, 1988; Darnall, 1985; Suguihara, Bancalari, Bancalari, Hehre and Gerhardt, 1986). To test the possible relationship between the cardiovascular and ventilatory response to hypoxia in the newborn, eleven sedated spontaneously breathing piglets (age: 5.9 ± 1.6 days; weight: 1795 ± 317 g; SD) were studied before and after alpha adrenergic blockade with phenoxybenzamine. Minute ventilation (V(E)) was measured with a pneumotachograph, cardiac output (CO) by thermodilution and total and regional brain blood flow (BBF) with radiolabeled microspheres. Measurements were performed while the animals were breathing room air and after 10 min of hypoxia induced by breathing 10% O2. Hypoxia was again induced one hour after infusion of phenoxybenzamine (6 mg/kg over 30 min). After 10 min of hypoxia, in the absence of phenoxybenzamine, the animals responded with marked increases in VE (P < 0.001), CO (P < 0.001), BBF, and brain stem blood flow (BSBF) (P < 0.02). However, the normal hemodynamic response to hypoxia was eliminated after alpha adrenergic blockade. There were significant decreases in systemic arterial blood pressure, CO, and BBF during hypoxia after phenoxybenzamine infusion; nevertheless, V(E) increased significantly (P < 0.001). The dissociation between the ventilatory and cardiovascular responses to hypoxia after phenoxybenzamine administration suggests that, within the limits of this study, the ventilatory response to hypoxia in the neonatal piglet is independent of changes in circulation or brain perfusion.

Original languageEnglish
Pages (from-to)289-295
Number of pages7
JournalJournal of Developmental Physiology
Volume15
Issue number5
StatePublished - Oct 28 1991

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Adrenergic Agents
Ventilation
Phenoxybenzamine
Brain
Cardiac Output
Respiration
Hemodynamics
Hypoxia
Thermodilution
Regional Blood Flow
Microspheres
Respiratory Insufficiency
Brain Stem
Arterial Pressure
Perfusion
Air
Weights and Measures

ASJC Scopus subject areas

  • Developmental Biology
  • Physiology

Cite this

Effect of alpha adrenergic blockade on brain blood flow and ventilation during hypoxia in newborn piglets. / Suguihara, C.; Bancalari, Eduardo; Hehre, D.; Osiovich, H.

In: Journal of Developmental Physiology, Vol. 15, No. 5, 28.10.1991, p. 289-295.

Research output: Contribution to journalArticle

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