High Muscle Tone Research Articles

STUDIES OF THE THYROID APPARATUS. V. THE SIGNIFICANCE OF THE COMPARATIVE MORTALITY RATES OF PARATHYROIDECTOMIZED WILD NORWAY RATS AND EXCITABLE AND NON-EXCITABLE ALBINO RATS

In the first paper of this series (1) a report was made of a comparative study of the mortality rate of two groups of parathyroidectomized albino rats. Although the members of both groups were descendants of the same parent stock they differed in the general trend of their excitability or readiness to respond to exogenous stimuli and consequently in their muscle tone. The one group, called the “Stock Albinos,”, presented the normal picture of low threshold of response to stimulation and high muscle tone. These rats were easily excited. The mortality rate within 48 hours after parathyroidectomy was 79 per cent and was accompanied by tetania parathyreopriva. In the other group, designated as the “ Gentled Albinos,” in which excitability and muscle tone had been reduced to a low level by constant handling and petting, the mortality rate was but 13 per cent.