Abstract
Sheep do not show any convulsive symptoms or visible distress after intravenous administration of insulin even when the blood sugar is depressed to 30 mg. per 100 cc. It is possible that the convulsive level for sheep would be lower, but so far we have been unable to reach it. With increased dosage the effect is not so much upon the intensity as upon the duration of the hypoglycemia.
It has been shown 1 that recovery from the lowest sugar value begins immediately after it has been reached, if about 5 units per 100 pounds are injected intravenously.
When 10 units were administered, the hypoglycemia, at or near the lowest level, lasted about one hour. When 15 units were injected, the low level was maintained about two to three hours.
Thyroidectomized sheep have been reported 2 to show a similar flat bottom in their insulin blood sugar curves after the small dose (5 units) which failed to produce it in the normal animal. In the light of the evidence then available, it was suggested that this effect of thyroidectomy might be due to the lack of the thyroid secretion, assumed to aid normally in the control of the blood sugar through its effect upon glycogenolysis.
The standard conditions of the experiments included an Interval of about eighteen hours between the last meal of the sheep and the beginning of each experiment.
This interval was varied and a longer fast was instituted. Under the changed conditions, the normal sheep showed a flat bottom in the insulin blood sugar curve after the administration of the standard dose.
On the other hand, when the thyroidectomized sheep were allowed free access to food during the night preceding the experiment, blood sugar curves were obtained indistinguishable from the curves of normal animals which had been given the same dose of insulin but had been submitted to the standard eighteen hours'rast.
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