Summary: Local cerebral blood flow (LCBF) was eval uated with the [14C]iodoantipyrine quantitative autoradio graphic technique in 29 brain structures in conscious con trol rats and during fentanyl-induced electroencephalo graphic (EEG) spike and/or seizure activity and in the postseizure EEG suppression phase. During spike ac tivity, LCBF increased in all structures; the increase reached statistical significance (p < 0.05) in the superior colliculus, sensorimotor cortex, and pineal body (+ 130%, + 187%, and + 185% from control, respec tively). With progressive development of seizure activity, LCBF significantly increased in 24 brain structures (range, +58% to +231% from control). During the post seizure EEG suppression phase, LCBF remained ele vated in all structures (+ 80% to + 390% from control).High-dose narcotic anesthesia can elicit seizure activity in laboratory animals as well as under clin ical conditions (De Castro et aI., 1979; Sebel et aI., 1981; Bovill et aI., 1982; Rao et aI., 1982). In a re cent report, the increase in brain oxygen uptake due to fentanyl-elicited convulsive activity was not matched by an equivalent compensatory elevation in overall CBF (Carlsson et aI., 1982). This finding suggests that cerebral ischemia could result due to This paper was presented in part at the Annual Meeting of the American Society of Anesthesiologists, Las Vegas, Nevada, Oc tober 1982.Dr. Maekawa is a Research Fellow in Neuroanesthesia Re search at the University of California at San Diego; he is also affiliated with the Department of Anesthesiology, Yamaguchi University, Yamaguchi, Japan.Dr. Tommasino is a Research Fellow in Neuroanesthesia Re search at the University of California at San Diego; she is also affiliated with the Department of Anesthesia, University of Na ples, First Medical School, Italy.Address correspondence and reprint requests to Dr. Shapiro at Neuroanesthesia Research, M-004, University of California at San Diego, La Jolla, California 92093, U.S.A.Abbreviations used: CMR, Cerebral metabolic rate; LCBF, local cerebral blood flow; LCMR g 1u, local cerebral metabolic rate for glucose; LCVR, local cerebrovascular resistance.
88The local cerebrovascular resistance (LCYR) signifi cantly decreased in 10 of 29 structures with the onset of spike activity (range, -24% to -64%), and remained decreased in all brain structures during seizure activity (range, -34% to -67%) and during the EEG suppression phase (range, -24% to -74%). This reduction of LCVR
METHODS
Local cerebral blood flow (LCBF) was measured in 23Sprague-Dawley rats with the [14C]iodoantipyrine quan titative autoradiographic technique (Reivich et aI., 1969; Sakurada et a1., 1978). The rats weighed 289 ± 20 g (mean ± SD) and were studied while conscious and during fen tanyl administration, resulting in electroencephalographic (EEG) patterns consisting of spike, seizure, and postsei zure suppression activity.
Fentanyl-treated animalsThe rats were briefly anesthetized with 1.5% halothane and 70% nitrous oxide in oxygen to permit tracheost...