exam07A - PHA 5515 Final Exam Form A Total 128 points Read...

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PHA 5515 April 28, 2007 Final Exam Form A Total: 128 points Read each question carefully before answering. Answer only the question that is written on the page; don’t add any of your own parts to it. When taking this exam, you must agree to abide by the following policy: We, the members of the University of Florida community, pledge to hold our peers and ourselves to the highest standards of honesty and integrity. On my honor, I have neither given nor received unauthorized aid on this examination. No calculators are needed. Please keep the test and turn in answer sheets when you have finished. Good Luck!
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True/False (2 pt s each) Varenicline is a recently approved drug that is used to decrease cravings for cigarettes in smokers who are trying to quit (Figure 1). Nicotine, mecamylamine, cytisine and another new drug, XXX, also decrease cigarette cravings to different degrees but these drugs have many side effects including nausea (Figure 2). You suspect that these efficacies are based on the ability of these drugs to bind to different subtypes of nicotinic receptors. Therefore you compare the efficacies and potencies of these drugs to displace the specific binding of 3 H-nicotine from its receptors in homogenized brain samples (Figure 3). Varenicline and cytisine can only bind to 30% of the sites occupied by 3 H-nicotine (the V receptor subtype) while Drug XXX can only bind to the other 70% of the receptors (the X receptor subtype). Which of the following conclusions would be true? A = True, B = Not True, If you don’t have any evidence to prove that the statement is true, then answer “not true”. 1. Mecamylamine and nicotine can bind to both V and X receptor subtypes but the IC 50 values for the two subtypes are more alike for nicotine than they are for mecamylamine. 2. Cytisine can not bind specifically to any nicotine receptor subtype at these concentrations. 3. Varenicline clearly has a lower affinity for the V receptor subtype compared to nicotine’s affinity for the V receptor subtype. 4. Varenicline would be able to compete for at least a portion of specific binding if a competition curve were performed using 3 H-cytisine as the radiolabeled drug. 5. Cytisine would be able to compete for at least a portion of specific binding if a competition curve were performed using 3 H- XXX as the radiolabeled drug. 6. Mecamylamine clearly has a lower affinity for the V receptor subtype compared to its affinity for the X receptor subtype. 7. You would suspect that 70% of the nicotine receptors (X receptor subtype) are involved in the nausea caused by these drugs. 8. You would suspect that 30% of the nicotine receptors (V receptor subtype) are involved in the anticraving effects of these drugs. 9.
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exam07A - PHA 5515 Final Exam Form A Total 128 points Read...

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