Ak. Curran et al., Lesion or muscimol in the rostral ventral medulla reduces ventilatory output and the CO2 response in decerebrate piglets, RESP PHYSL, 123(1-2), 2000, pp. 23-37
Developmental abnormalities have been described in the arcuate nucleus of s
udden infant death syndrome (SIDS) victims. The arcuate nucleus has putativ
e homologues in chemosensitive areas of the ventral medulla in animals. We
refer to some of these areas collectively as the rostral ventral medulla (R
VM). In the RVM of decerebrate piglets 2-15 days of age, we studied the eff
ects of electrolytic lesions (n = 7) or microdialysis of muscimol (n = 15),
a GABAA receptor agonist, on ventilatory output and the response to hyperc
apnia. Lesions caused a 66.7 +/- 17.3% reduction in eupneic phrenic minute
activity (MA) and abolished the response to hypercapnia. Muscimol dialysis
caused a 32.4 +/- 10.4% reduction in MA with a significant downward displac
ement of the response to hypercapnia with no significant effect on the slop
e. We conclude that the piglet RVM contains neurons of vital importance in
the maintenance of normal breathing and the response to systemic CO2. We hy
pothesize that dysfunction of homologous regions in the human infant could
lead to impaired ability to respond to hypercapnia and could potentially be
involved in the pathogenesis of SIDS. (C) 2000 Elsevier Science B.V. All r
ights reserved.