[Effects of narcotic analgesics on somatosympathetic reflex discharges in anesthetized cats: buprenorphine and naloxone].
Effects of buprenorphine and naloxone on the sympathetic reflex evoked in the inferior cardiac nerve following electrical stimulation to the ipsilateral superficial peroneal nerve were investigated in 29 cats under satisfactory anesthesia with urethane and alpha chloralose. Two components of the somato-sympathetic reflexes with two different latencies were recorded. The early component was due to an activation of myelinated A afferent (referred to as A reflex), while the late component was due to an activation of unmyelinated fibers (referred to as C reflex). Intravenous injection of buprenorphine (0.006 mg.kg-1) depressed neither A or C reflex. A somewhat larger dose of buprenorphine (0.06 mg.kg-1) markedly depressed C reflex. A larger dose of buprenorphine (0.3 mg.kg-1) antagonized the depressive effects of buprenorphine (0.06 mg.kg-1) on C reflex. Naloxone (0.2 mg.kg-1 i. v.) antagonized the depressive effects of buprenorphine (0.06 mg.kg-1) on C reflex in 7 cats in which C reflex had been depressed less than 50% of control with buprenorphine 0.06 mg.kg-1. In other 5 cats naloxone (0.2 mg.kg-1) did not antagonize the depressive effects of buprenorphine (0.06 mg.kg-1) on C reflex which had been depressed more than 50% of control with buprenorphine 0.06 mg.kg-1. The present results suggest that buprenorphine has an effect which is called "non competitive autoinhibition", and the somato-sympathetic C reflex can be a useful indicator of analgesics in satisfactorily anesthetized cats.
Kato
J
J
Department of Anesthesiology, Surugadai-Nihon, University Hospital, Tokyo.
Saeki
S
S
Ogawa
S
S
D000758:Anesthesia; D000818:Animals; D002047:Buprenorphine / Q000494:pharmacology*; D002415:Cats; D009270:Naloxone / Q000494:pharmacology*; D012018:Reflex / Q000187:drug effects*
D009270:Naloxone; D002047:Buprenorphine