EFFECT OF LOW AND HIGH CONCENTRATIONS OF ALFENTANIL ADMINISTERED INTRATHECALLY ON A{delta} AND C FIBRE MEDIATED SOMATOSYMPATHETIC REFLEXES

We have studied the effects of alfentanil administered intrathecallyon somatosympathetic reflexes evoked by stimulation of radialand tibial nerves in 10 anaesthetized and paralysed dogs. Infive animals, alfentanil was administered in doses of 100, WO,200 and 400 µ in 0.8 ml and 800 µ in 1.6 ml preparedfrom the formulation of 500 µ mt^–1. Five othersreceived alfentanil (high concentration formulation, 5 mg mf^–1)in doses of 500 and 2000 µ in 0.5 ml and 5000 µin 1 ml. C fibre tibial nerve reflexes were depressed by 100µ and abolished with doses of 200–400 µ, butthe A