C. Beyaert et al., IMPROVED RECOVERY FROM LARYNGEAL-STIMULATION-INDUCED APNEA BY ALPHA-ADRENERGIC BLOCKADE IN ADULT-RABBITS, Biology of the neonate, 70(6), 1996, pp. 359-362
The apnea triggered by laryngeal stimulation (LS) is associated with a
redistribution of blood flow towards the heart and the brain that dep
ends upon peripheral vasoconstriction. The circulatory component of th
e response to LS has been shown to be reduced following injection of l
arge dose of beta-adrenergic agonist that more intriguingly blunted th
e ventilatory response as well. To test whether the reduction of LS-in
duced apnea could be related to the decreased magnitude of the periphe
ral vasoconstriction, the effects of the a-adrenergic antagonist urapi
dil on the ventilatory and blood pressure responses to LS were studied
in 6 adult rabbits. alpha-Adrenergic blockade reduced both the rise i
n blood pressure and the magnitude of hypopnea induced by LS. These re
sults suggest that the circulatory component of the laryngeal chemoref
lex, i.e. the peripheral vasoconstriction, contributes to the magnitud
e of the ventilatory depression.