| Objective The purpose of the study was to investigate the potential antinoci-ceptive effects of propofol and thiopental on the changes in the discharge rate ofneurons in parafascicular (PF) nucleus of thalamus evoked by coronary arteryocclusion.Methods SD rats (270~280g) were anesthetized by intraperitoneal injectionof urethane (1.2mg/Kg). The animal was intubated and ventilated with a rodentventilator. The heart was exposed by an incision made in the fourth leftintercostal space, and an opening was made in the pericardium.The left anteriordescending (LAD) branch of coronary artery was instrumented with a snareoccluder. Then the thoracic cavity was evacuated, and the insision was closed bylays. The spontaneous respiration was restored. Afterwards, the rat was securedin the stereotaxic frame and craniotomy made with drilling hole in the skull andexcision of the dura for penetration of the recording electrode. The rats showedresponses to somatic noxious stimulation and to coronary artery occlusion (CAO)were randomly divided into six groups, 6 animals each. Group I: with CAO plusNS 0.1ml,iv; Group II: with CAO plus propofol 0.02 mg/Kg,iv; Group III: withCAO plus propofol 0.2mg/Kg,iv; Group IV: with CAO plus propofol 2mg/Kg,iv;Group V: with CAO plus thiopental 0.5mg/Kg,iv; Group VI: with CAO plusthiopental 5mg/Kg,iv. Propofol or thiopental was administered intravenously 15minutes after the onset of CAO. The experiment recordings lasted for 60minutes. The maximal doses of propofol and thiopental in the experiment weretested on 12 other separate animals for possible anaesthetic effects.Results Propofol (0.2mg/Kg,2mg/Kg) and thiopental (5mg/Kg) significantlysuppressed the increase in the discharges of NSRN induced by CAO (P<0.05)and the doses of propofol, 2mg/Kg and thiopental, 5mg/Kg did not produceanesthetic effects on the rats.Conclusions Propofol and thiopental (at subanesthetic doses) may haveantinoncieptive effects on visceral pain evoked by mycardiac ischemia.
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