Cerebral ischemia was produced in the Mongolian gerbil by bilateral occlusion of the carotid arteries. Although the cerebral ischemia so produced was not total, a mortality rate of 100% was obtained if the occlusion was maintained for 60 min in gerbils weighing 45--55 gm. Few deaths were observed after 50 min of bilateral carotid arterial occlusion. Test drugs were administered, after the removal of the arterial clips, to groups of gerbils to determine the mortality rate associated with each drug. Isoproterenol 50 mg/kg, amphetamine 5.0 mg/kg, and methylprednisolone 35 mg/kg improved survival after cerebral ischemia. Atropine 1 mg/kg, thiosemicarbazide 4 mg/kg, aminooxyacetic acid 100 mg/kg, theophylline 100 mg/kg, and phenytoin 50 mg/kg were associated with a reduced survival after cerebral ischemia. The known tendency of the gerbil to exhibit spontaneous seizures and the frequency and severity of the observed post-ischemic seizures suggest that the lethality of prolonged cerebral ischemia may be, in part, related to seizures triggered by the cerebral ischemia.

Aminooxyacetic Acid↗

PubMedDate not supplied

Ototoxicity of intracisternal gentamicin in cats.

The intrathecal administration of gentamicin has been used to treat bacterial meningitis. However, the influence of this route of administration on the well-known ototoxic activity of gentamicin is unknown. This route of administration should facilitate access to the inner ear and should increase the ototoxic liability. The possible ototoxic and neurotoxic effects of intrathecally administered gentamicin (0.5, 1, 2, 4, 6, 10 mg/day) in cats were evaluated. Hearing thresholds were obtained by a noninvasive technique prior to and on the 7th and 21st days after the initiation of a seven-day dosage regimen. Histological examination of the organ of Corti was routinely done. Additionally, the vestibular organs of one animal on the 4 mg/day regimen were examined. The concentrations of gentamicin in the cerebrospinal fluid were also determined. The data indicate that the 2 mg/day dose may be very close to the threshold dose for ototoxicity when gentamicin is given by intracisternal administration.

Animals↗

PubMedDate not supplied

Comparisons of selected cardiovascular responses in dogs anesthetized with electricity, pentobarbital or methoxyflurane.

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Acetylcholine↗