Dose-Effect Relationship Between Insulin and Blood Glucose

Description: This video film shows a simple experiment in which the effect of an increasing dose of insulin on blood glucose level is investigated. After studying this video film the user should be able to: Describe the successive steps that are carried out in this experiment; Describe the procedure of blood sampling; Discuss the results of the study. This film not only describes and discusses the experiment but also pays a good deal of attention to the procedure of blood sampling. During repeated sampling it is important to avoid stress in the rat due to loss of blood. This can be achieved by replenishing the removed blood with a transfusion of fresh whole rat blood, recently taken from a donor rat by cardiac puncture, and warmed to 41-42 °C for 5 minutes prior to the transfusion. This is also shown in the video film. The rats in the experiment are provided with a single cannula which is used for blood sampling as well as insulin infusion. When continuous infusions are administered it is also possible tp provide the rats with a permanent double heart catheter. The hormone insulin is important to keep the blood glucose at a constant level. Glucose is a very important fuel for the body and especially for the central nervous system. The hormone insulin, released by the b-cells of the endocrine pancreas, has a predominant role in stabilizing the blood glucose level. The aim of this experiment is to investigate the dose-effect relationship between insulin and blood glucose. In addition, the effect of food intake is studied. The experiment is carried out in four male Wistar rats. All rats are provided with a permanent heart catheter. Before (t= -10 and 0 min) and after insulin injection (t=5, 10, 15, 20, 30, 45 and 60 min) blood samples are taken for determining the blood glucose. Three doses of insulin are injected: 0.1 IU (rat 1), 0.3 IU (rat 2) and 1.0 IU (rats 3 and 4). Rats 1, 2 and 3 had no access to food, in contrast to rat 4. Results are: The return of blood glucose to its pre-injection level is influenced by the insulin dose and by food intake: when the insulin dose is higher the glucose preinjection level is passed off more slowly. As soon as rat 4 starts the glucose level rises and at t= 60 minutes the level is higher than that in rat 3. This study demonstrates a clear dose-effect relationship of insulin and blood glucose. The decreasing blood glucose level stimulates the rat to start eating, which results in a faster return to normal blood glucose levels.

Comments & References: Running time: 19 minutes.

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