Blood-brain barrier integrity and brain water and electrolytes during hypoxia/hypercapnia and hypotension in newborn piglets.
This study examines the effects of hypoxia/hypercapnia and hypoxia/hypercapnia with hypotension (hypotensive-hypoxia/hypercapnia) on blood-to-brain transfer constants (K1) for sodium and mannitol and brain water and electrolyte contents in newborn piglets. Hypoxia/hypercapnia was induced for 60 min with the piglets breathing a gas mixture of 15% carbon dioxide, 10-12% oxygen, and 73-75% nitrogen adjusted to achieve an arterial pH less than 7.15, pO2 less than 40, and pCo2 greater than 60 mmHg and hypotension for 20 min by rapid phlebotomy to achieve a mean arterial blood pressure less than 40 mmHg. Piglets were studied during 1 h of, and 24 h after resuscitation from hypoxia/hypercapnia (arterial pH 6.9 +/- 0.18, pO2 36 +/- 6 mmHg, pCO2 68 +/- 8 mmHg, mean +/- S.D.) and 10 min, and 24 h after resuscitation from hypotensive-hypoxia/hypercapnia (mean arterial blood pressure 28 +/- 10 mmHg, mean +/- S.D.). Values for K1 for sodium and mannitol, measured using the integral technique were 15.9 and 5.2 ml.g-1.min-1 x 10(4) respectively, in 2-4-day-old controls, suggesting that the barrier is fully developed in newborn piglets. Values were not different during or after hypoxia/hypercapnia or 24 h after hypotensive-hypoxia/hypercapnia. Ten to forty min after hypotensive-hypoxia/hypercapnia, there was a proportional decrease in the K1 for sodium and mannitol of about 40%. These results suggest that the newborn piglet is similar to the adult with respect to impermeability of the blood-brain barrier to ions and small molecules and resistance of this barrier to systemic hypoxia/hypercapnia and hypotension.(ABSTRACT TRUNCATED AT 250 WORDS)
Stonestreet
B S
BS
Department of Pediatrics Women and Infants' Hospital of Rhode Island, Providence 02905.
Burgess
G H
GH
Cserr
H F
HF
D000818:Animals; D000831:Animals, Newborn; D001812:Blood-Brain Barrier / Q000502:physiology*; D001834:Body Water / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology; D004573:Electrolytes / Q000378:metabolism*; D006935:Hypercapnia / Q000378:metabolism*; D007022:Hypotension / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D008353:Mannitol / Q000493:pharmacokinetics; D008970:Molecular Weight; D012964:Sodium / Q000493:pharmacokinetics; D013552:Swine
D004573:Electrolytes; D008353:Mannitol; D012964:Sodium