Thresholds for Pain and Convulsions in the Guinea Pig Following Massive Whole-body Irradiation

Abstract

Summary

Pain thresholds were tested using the thermal radiation from a projection bulb as a stimulus, and convulsive thresholds to electric shock were determined with ear-electrodes. Radiation doses of 5,000 r and 10,000 r were used to bracket the critical 6,000 r dose, above which signs of nervous system injury predominate. Pain thresholds remained relatively constant at each radiation dose until the animals became moribund. Convulsive thresholds were relatively constant at a dose of 5,000 r but dropped sharply following 10,000 r. Pentobarbital given prior to 10,000 r prevented the drop in convulsive threshold even after the obvious drug effects had disappeared. The essential constancy of the pain threshold response indicates that function is relatively unimpaired in a large portion of the nervous system.