CARDIORESPIRATORY AND SLEEP-WAKE BEHAVIOR IN DEVELOPING SWINE - KAPPA-OPIOID INFLUENCE

Effects of specific kappa-opioid antagonism with norbinaltorphimine (N orBNI) on sleep-wake state, blood pressure and heart rate, and on diap hragmatic and posterior cricoarytenoid electromyographic activities we re assessed in 3 to 13 and 23 to 33 day-old, chronically instrumented, unanesthetized piglets. Preliminary experiments established the pharm acodynamics and dose-response for NorBNI. In the main study, each pigl et was studied twice daily, once before and once after 3.7 mgkg(-1) No rBNI iv, for up to five consecutive days. During each study session, p iglets underwent 10 min trials with 21% O-2 in 79% N-2 followed by 10% O-2 in 90% N-2 while lying in a sling within a plexiglass box. Sleep- wake distribution and cardiorespiratory functions matured with age. No rBNI produced a modest increase of arterial pressure and heart rate in the older group only, and altered neither state nor respiration at ei ther age. These results suggest that, in the developing piglet model, the kappa-opioid system influences neither breathing nor state, but mo dulates cardiovascular regulation to a modest degree and later in onto geny.