title: Effects of phenobarbital on cerebral blood flow and metabolism in young and aged rats.
abstract: The cerebrovascular and cerebral metabolic changes produced by intraperitoneal injection of phenobarbital (50, 150, and 250 mg/kg) were studied in young adult (6-month) and senescent (28-month) Wistar rats. Cerebral blood flow (CBF) was measured using radioactive microspheres and cerebral oxygen consumption (CMRO2) was obtained by multiplying cortex CBF by the arterial-sagittal sinus oxygen content difference. Control values for blood pressure, blood gas tensions, CBF, and CMRO2 were similar in the young and aged animals during 70% N2O/30% O2. Intraperitoneal phenobarbital produced dose-dependent decreases in CBF with no significant difference between young and aged rats at each phenobarbital dose. At the highest phenobarbital dose (250 mg/kg) CBF was reduced by 49% in the young rats and 52% in the aged rats (P greater than 0.10). CMRO2 was also depressed in a dose-dependent fashion in both young and aged animals with each phenobarbital dose. However, the decrease produced by the highest phenobarbital dose was significantly greater in the aged rats (55%) than the young rats (43%, P less than 0.05), even though the EEG was isoelectric in both groups. The difference in CMRO2 between young versus aged rats at a time when the EEG is isoelectric suggests that high-dose phenobarbital may depress nonelectrical cerebral metabolic processes more in aged rats.
mesh_terms: D000375:Aging; D000769:Anesthesia, Inhalation; D000818:Animals; D001794:Blood Pressure; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002245:Carbon Dioxide / Q000097:blood; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D006221:Halothane; D007274:Injections, Intraperitoneal; D009609:Nitrous Oxide; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption; D010634:Phenobarbital / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D002245:Carbon Dioxide; D009609:Nitrous Oxide; D010100:Oxygen; D006221:Halothane; D010634:Phenobarbital