Abstract
Scott and Dotti 1 have made an extended study of blood sugar lowering effects of insulin given subcutaneously to rabbits. They have concluded that the results, when expressed as the fraction of sugar removed, are independent of the initial blood sugar while the absolute value of blood sugar after a given time interval or the absolute value of the fall in blood sugar is dependent on the initial value. It is, therefore, the fraction removed and not any of the absolute values which is related only to the insulin dose. They have studied the effect after one given time interval which is empirically chosen. Observations taken at later time intervals cannot be used because the blood sugar under their conditions tends to return too early towards the initial level.
Elsewhere 2 we have stated that after pancreatectomy in the dog the blood sugar in response to intravenous insulin falls continuously for a much longer period of time than in the normal animal. The factor which tends to early return towards the initial level has been eliminated. Under favorable conditions (relatively refractory animal) and with large doses of insulin a continuous drop in sugar can be observed for more than 2 hours. If under these conditions the observations of Scott hold for the entire course of the curve, the results should show a linear relation between the logarithm of the blood sugar and the time. The graph, Curve I, shows an example of a time curve after 10 units of insulin given intravenously in a depancreatized dog. By intravenous administration we reduce materially the latent period and eliminate any effects resulting from a possible gradual absorption from the site of injection. In the diabetic dog the duration of action of insulin is markedly dependent on the dose. It is therefore only after large doses that curves having the requisite number of observations over a sufficient period of time are obtained. With smaller doses the points will also fall along a logarithmic curve but the time range of observation is limited.
We have so far obtained a large number of curves (over 50) with small doses, giving a blood sugar minimum at about 60 minutes.
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