Ventilatory effects of naloxone via the sympathoadrenal system in the neonate?
Rabbit pups responded to hypoxia (6% O2 in N2) with a biphasic respiratory pattern, an initial increase by 1 min followed by a decrease. Naloxone (0.8 mg/kg) was found to abolish the declining phase of hypoxia, showing a sustained increase of ventilation throughout the hypoxic challenge. Phentolamine (30 micrograms/kg), an alpha-blocker, had no effect on the normal hypoxic response. However, pretreating the pups with phentolamine and then administering naloxone resulted in a biphasic response to hypoxia. We propose that the naloxone effects on ventilation are mediated in conjunction with the adrenergic system.
Srinivasan
M
M
Nobel Institute for Neurophysiology, Karolinska Institutet, Stockholm, Sweden.
Yamamoto
Y
Y
Lagercrantz
H
H
D000311:Adrenal Glands / Q000187:drug effects / Q000502:physiology*; D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D000860:Hypoxia / Q000503:physiopathology*; D009270:Naloxone / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology*; D011817:Rabbits; D012119:Respiration / Q000187:drug effects*
D009270:Naloxone; D010646:Phentolamine