Dexamethasone pretreatment attenuates cerebral vasodilative responses to hypercapnia and augments vasoconstrictive responses to hyperventilation in newborn pigs

Kirsti Heinonen, Alexander Fedinec, Charles Leffler

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

In the perinatal period, glucocorticoids are frequently administered to enhance pulmonary maturity or prevent chronic lung disease of prematurity. Recently, it has been suggested that the perinatal exposure to glucocorticoids can be associated with unfavorable neurologic development. We studied the hypothesis that 24-h pretreatment with glucocorticoid might modify cerebrovascular responses to high and low partial arterial CO2 tension in newborn animals in vivo. A closed cranial window was implanted over the left parietal cortex of 20 anesthetized ventilated newborn (<3 d old) pigs. The actual experiments were carried out in 15 pigs: eight pretreated with a total dose of 6 mg/kg of dexamethasone and seven controls. Five pigs were used for preliminary experiments as described in the text. Pial arteriolar diameters were measured during 1) baseline conditions (normocapnia), 2) hypercapnia induced by ventilating the animals with a gas mixture containing 10% CO2, or 3) hyperventilation with resultant hypocapnia. Under these conditions, the concentrations of 6-keto-PGF, in the CSF were measured in five experimental animals and six controls. In summary, the dexamethasone pretreatment 1) attenuated the hypercapnia-induced dilator responses of pial arterioles and prevented the hypercapnia-associated fall in mean arterial blood pressure; 2) caused moderate, although not statistically significant, diminution in 6-keto-PGF, levels in the CSF during baseline; 3) blocked hypercapnia-induced elevation of 6-keto-PGF; and 4) enhanced vasoconstrictive arteriolar responses to hyperventilation. We speculate that in the clinical setting, the dexamethasone effects may compromise the adjustments of global or regional cerebral blood flow to changing physiologic states in neonates.

Original languageEnglish (US)
Pages (from-to)260-265
Number of pages6
JournalPediatric Research
Volume53
Issue number2
DOIs
StatePublished - Feb 1 2003

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Hyperventilation
Hypercapnia
Dexamethasone
Swine
Glucocorticoids
Arterial Pressure
Cerebrovascular Circulation
Hypocapnia
Newborn Animals
Parietal Lobe
Regional Blood Flow
Arterioles
Nervous System
Lung Diseases
Chronic Disease
Gases
Lung
prostaglandin F1

All Science Journal Classification (ASJC) codes

  • Pediatrics, Perinatology, and Child Health

Cite this

Dexamethasone pretreatment attenuates cerebral vasodilative responses to hypercapnia and augments vasoconstrictive responses to hyperventilation in newborn pigs. / Heinonen, Kirsti; Fedinec, Alexander; Leffler, Charles.

In: Pediatric Research, Vol. 53, No. 2, 01.02.2003, p. 260-265.

Research output: Contribution to journalArticle

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