29 Questions
What is the structure of insulin?
An A chain and a B chain connected by two disulfide bonds
What is the mechanism of insulin action?
Binds to specific high-affinity receptors on the plasma membrane
What is the role of the β-subunits of insulin receptors?
Activation of tyrosine kinase activity
How are insulin receptors structured?
Two α-subunits and two β-subunits connected by disulfide bonds
Which proteins are recruited by insulin to mediate glucose transport?
GLUT4 transport proteins
What is the primary effect of metformin in treating diabetes?
Reducing the hepatic production of glucose
How do clinicians usually classify metformin in terms of its effect on weight?
Weight neutral
What is metformin primarily referred to as in the text?
Anti-hyperglycemic agent
Which transporters are involved in the absorption of metformin into hepatocytes from the portal vein?
OCT1
What effect does metformin have on mitochondrial respiratory-chain complex 1?
Inhibits it
In what way is the efficacy of metformin compared with oral sulfonylureas?
Effects on fasting plasma glucose and HbA1c levels
What is the role of the PIP3 kinase pathway in cellular function?
Phosphorylation of GLUT 4 transporter and transcriptional changes in metabolic enzymes.
How does the modulation of mRNA transcription by insulin contribute to cellular function?
Enhances expression of genes involved in growth and survival.
What is one way insulin affects cellular signaling pathways?
Activation through ras signaling complex in the MAP kinase pathway.
Which is NOT a type of insulin among those mentioned?
Insulin analogues.
Insulin-mediated gene expression mainly involves genes related to _____
Cell growth and proliferation.
What is the primary function of the MAP kinase pathway in response to insulin?
Mediates cell growth, proliferation, and survival.
What is the goal of therapy in diabetics?
Reduce HbA1c levels to below 7%
What is a distinctive characteristic of sulfonylureas?
Potent hypoglycemic agents
How do sulfonylureas primarily stimulate insulin release?
Depolarization of the pancreatic β-cell
What caused some patients to die in the early 1940s when treated with sulfa drugs for typhoid fever?
Hypoglycemia
Why were sulfonylureas not initially considered for treating diabetes?
Side effects of hypoglycemia
Which drug class binds to a receptor associated with KATP channels in the pancreatic β-cell membrane?
Sulfonylureas
Which Sulfonylurea drug has an extended length of action available in 5 or 10 mg once a day dose?
Glipizide
What is the primary reason for increased therapeutic effects and elevated risk of hypoglycemia in patients with reduced kidney function taking glyburide?
Fast renal clearance of metabolites
Which sulfonylurea drug undergoes liver metabolism to weakly active metabolites, which do not substantially contribute to the overall HbA1c lowering effects?
Glipizide
What is the primary difference in the action duration between Sulfonylureas and Meglitinides?
Meglitinides reduce blood glucose levels
Which Sulfonylurea drug has an active metabolite with 33% activity compared to the drug itself?
Glimepiride
Why might the 2nd generation agents lead to more troublesome overdoses compared to other antidiabetic drugs?
Due to their long durations of action
Learn about the chemistry of insulin, including its two polypeptide chains and disulfide bonds, as well as its mechanism of action by binding to specific high-affinity receptors on the plasma membrane.
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