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10-07-2006, 10:05 AM
A pt is participating as part of a research study related to diabetes. The investigators want to measure the levels of proinsulin-derived C peptide in his blood after various stimuli. Which of the following agents would cause the lowest level of circulation C-peptide?

a) Glucagon

b) Clonidine

c) Terbutaline

d) CCK

e) Theophylline

Ans:It took me by surpire.. Clonidine. Alpha2 receptor agonists directly inhibit pancreatic insulin secretion, thereby decreasing secretion of proinsulin-derived C peptide. Proinsulin is cleaved to yield insulin and a C-peptide. GI hormones such as glucagon, gastrin, secretin and CCK stimulate insulin secretion and therefore they increase C-peptide levels. Terbulatine is a beta 2 agonist, and would stimulate secretion of insulin and C-peptide. Theophylline increases the levels of cAMP which stimulaes the release of insulin and C-peptide.

Follow up question: What is the mechanism of action of theophylline?

10-07-2006, 10:50 AM
it is a bronchodilator..its mechanism of action is to inhibit the phosphodiesterase decreasing camp hydrolosis

10-07-2006, 11:11 AM
And glucagon will activate the production of insulin by a -feedback for himself.

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