In an experimental situation a group of 6 rats (group 1) are injected intravenou

Question

In an experimental situation a group of 6 rats (group 1) are injected intravenously with thyroxine. A second group of 6 rats (group 2) are injected via the same route with 3, 3',5' triiodothyronine. A third group of 6 rats (group 3) receives an intravenous injection of 3, 5, 3'-triiodothyronine. A fourth group of 6 rats (group 4) serve as controls for groups 1, 2 and 3, and are injected via the same route with the solution that is used to dissolve these hormones. All animals are housed at room temperature with food and water freely available. 1. Basal Metabolic Rate (BMR) in each of these animals is monitored every hour for 30 hours following the injections. A graph of BMR vs. time for each on the data presented in the graph, which lines on the graph (W, X, Y and Z) represent each treatment group? group is shown below. Based 70 60 50 40 G30 20 10 5 10 15 20 25 30 Time after injection (hours) 2. What would happen to BMR in group 1 (thyroxine injection) if these animals had been pre-treated with a drug that completely and rapidly inhibits activity of the deiodinase enzyme that converts T4 to T3 at target tissues?

Explanation / Answer

X appears to be group 3 as there is immediate action by the activated form.

Y appears to be group 1 as there is quite delayed response taken to convert thyroxine to triiodothyronine.

Z appears to be group 4 as decremental effects of more prominent due to giving solution that dissolve hormones.

W appears to be group 2 as inactivated form does not leads to any effect.

Part 2- BMR in that case would not increase and rather may decrease after sometime due to depletion of available triiodothyronine and inhibition of conversion of T4 to T3.

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