Abstract
A method is described for testing rats in groups of up to four using both first myoclonic jerk and sustained convulsion as endpoints in each animal. A niinirnum of individual handling of the animals is required, and large numbers can be tested by one Person. Thresholds are independent of weight over a wide range of weights, beyond which a small inverse relation may exist. Starvation lowers thresholds, but only after a large change in weight. There is no prominent difference between the sexes. Extracerebral factors such as airflow, blood flow and flurothyl diffusion across tissue boundaries theoretically can influence the measurement. A consistent result of repeated testing is a fall in thresholds, the first jerk sooner than the sustained convulsion. This is shown to be related to seizures rather than specific for flurothiyl. A possible explanation for it is anoxic damage to the brain or the blood-brain barrier. With modification of endpoint criteria, testing of nurshing rats, adult mice and adult guinea pigs is practical, but these animals respond differently to daily testing: Rats under approximately 4 to 6 weeks of age do not display a clear decline; in mice the two endpoints fall. but at the same rate; in guinea pigs there is a rise rather than a fall.
Footnotes
- Received May 21, 1968.
- Accepted November 6, 1968.
- © 1969, by The Williams & Wilkins Company
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