Failure of naloxone or beta-endorphin to affect pressure-induced tremor in guinea pig

Naloxone in doses up to 2 mg/kg and beta-endorphin in doses up to 1 mg/kg had no suppressive effect on pressure-induced tremor or cortical EEG activity in the guinea pig. The lack of effect of either naloxone or beta-endorphin on the HPNS provides evidence that opiate receptor mechanisms are not significantly involved in this syndrome.