Pharmacology - Insulin, Oral Hypoglycemic Agents, Glucagon (Exam 5) Flashcards
The principal hormone that’s dysregulated in diabetes
Insulin
What is signaled by the presence of usable energy and tells the body to store energy?
Insulin release
What is the structure of proinsulin?
A chain
B chain
C chain
Through the proteolytic cleavage of proinsulin, which chain gets cleaved?
C chain
T/F the C chain has no known physiological function
True
What is the active part of insulin?
A and B chain
What are A and B chains of proinsulin linked by?
Disulfide bonds
How do you inactivate insulin?
Hydrolyze the disulfide bond between A and B chain
Why do we care about the structure of insulin?
All therapies for type I diabetes are mimetics of insulin and have a similar structure
How fast is insulin’s half life?
3-5 mins
Where is endogenous insulin metabolized vs subcutaneously introduced insulin metabolized?
Endogenous: 60% liver, 40% kidney
Subcutaneous: 60% kidney, 40% liver
How much insulin does the pancreas hold?
8 mg (~200 units)
Which cells in the pancreas secrete insulin?
B cells
Name some secretory products of B cells
Insulin
C chain (peptide)
Proinsulin
Islet amyloid polypeptide (IAPP)
Which cells in the pancreas make glucagon?
A cells
T/F: The pancreas is mostly made up of alpha cells.
False! It’s mostly beta cells
Insulin secretion steps (7) (ON EXAM)
- High levels of glucose
- Glucose enters cell via GLUT2 and gets metabolized
- ATP is produced
- ATP phosphorylates and closes K+ channels
- Beta cell gets depolarized
- Voltage gated Ca2+ channels open
- Increased Ca2+ leads to the release of insulin
Most important step of insulin secretion
(this is what drugs that increase insulin secretion target)
When ATP closes the K+ channels and causes depolarization of the Beta cell
Insulin released from beta cells is a complex of what?
6 insulin molecules with 1 Zn atom
T/F when insulin is in a complex with Zinc, it cannot find its target receptor and it is NOT biologically active
True
Only the ___________ form of insulin is able to bind to the receptor
monomeric
3 insulin responsive tissues (ON EXAM)
- Liver
- Muscle
- Adipose
Insulin receptors have ___________ _________ activity
intrinsic enzymatic
Steps of insulin receptor signal transduction (ON EXAM)
- Insulin binds to insulin receptor
- IRS proteins are stimulated
- Glucose transporters (GLUT-4) move from intracellular vesicles to plasma membrane
Where is GLUT-2 transporter always located?
Plasma membrane
Where is GLUT-4 transporter located?
Translocates to the plasma membrane when activated by insulin receptor
Elevated levels of glucose leads to the release of ________ which leads to _________ _________
insulin; energy storage
Decreased levels of glucose leads to decreased levels of _________, which leads to the body using ________ ______ to make more ________
insulin; stored energy; glucose
Blood glucose levels serve as a ____________ for insulin action
surrogate