First Name: Required
   Last Name: Required
      E-mail: Required

BE SURE TO ENTER YOUR Email prefix (eg. "bolger" , not bolger@usc.edu) (not SS#, Not PID#) INTO THE CORRECT LOCATION ON THE SPREADSHEET OR YOU WILL NOT GET THE RIGHT ANSWERS!

Self-assessment questions:

The agonists used are alkyltrimethylammonium compounds that mimic the action of acetylcholine on the muscarinic receptors of the intestine. These muscarinic receptors belong to the G-protein coupled receptor superfamily. The receptor is a single subunit embedded in the basolateral membrane of the ileum, which has seven transmembrane spanning domains per subunit.

Notice the numbers 3.00E-07 and 56 under the cells labeled EC_50 and Emax respectively. These are the concentration of agonist required for half maximal response and the maximal response required to generate the smooth black line.

Try changing these values and notice the movement of the smooth black line. As you increase the EC_50, the black line moves right. As you increase the Emax, the black line moves upward. You will need to vary the values of these two dose response parameters to answer the following questions.

Please select the correct response to the following questions. When you are finished with Questions 1 - 5, press the spreadsheet tab labeled Questions6-8 etc. and continue to answer the Web Page questions. When you are finished press the send button and your responses will be E-mailed to Drs. Adams, Bolger, and Rho. You will receive 6 points of extra credit for completing this assignment.

BE SURE TO ENTER YOUR Email name INTO THE CORRECT LOCATION ON THE SPREADSHEET OR YOU WILL NOT GET THE RIGHT ANSWERS!
If your first and last name does not pop up in cells H2 and I2 then please contact Dr. Bolger.

1. The EC_50 of butyl-trimethylammonium is:
1E-08 2E-07 3E-06 1E-05

2. The ethyl-trimethylammonium compound is _______ times less potent than the butyl compound.
5 10 33 500

3. Which of the following are partial agonists?

1. hexyl-trimethylammonium
2. ethyl-trimethylammonium
3. octyl-trimethylammonium
4. nonyl-trimethylammonium

4. What is the maximal response for octyl-trimethylammonium?
65% 55% 45% 35%

5. How do the EC_50s for octyl-trimethylammonium and nonyl-trimethylammonium compare?
they are equal octyl is more potent than nonyl nonyl is more potent than octyl nicely

• Questions 6-8 relate to the dose response for a cellular receptor as opposed to the whole tissue as described in Questions 1-5. The receptor in question is a beta2-adrenergic receptor that is coupled to a stimulatory G-protein. When the concentration of norepinephrine is increased the concentration of intracellular cAMP rises as seen in the first figure. You will be conducting some experiments to determine the Ki value for a new beta2-selective antagonist.

As you change the concentration of the antagonist, the dose response for norepinephrine's effect on cAMP changes in a regular fashion. Your job will be to fill in the data for the accompanying Schild plot and determine the mechanism of antagonism (competitive or non-competitive) and the Ki for this new antagonist.

6. Start by changing EC_50 and Emax to determine the baseline values in the absence of antagonist. What are these values respectively?
EC_50 = 1E-8 and Emax = 100 EC_50 = 1E-7 and Emax = 50 EC_50 = 1E-7 and Emax = 100 EC_50 = 1E-6 and Emax = 100

7. Now change the antagonist concentration to match the values in cells G5-G8. After each change in antagonist concentration, recheck the new "best fit" values for EC_50 and Emax. Remember to fill in the observed value of EC_50 for each new antagonist concentration used. When you are finished the Schild plot should be linear and its intercept value corresponds to the antilog of Ki. Which of the following are closest to the observed intercept value?
4.5 5.5 6.5 7.5

8. Enter the intercept value in the J1 cell and select the closest Ki from the list below.
1E-08 3E-08 1E-07 3E-07 1E-06 3E-06

• Questions 9-12 relate to the dose response for an in vivo measurement of biological activity. When stimulated, the GABAa receptor is able to block convulsions in patients with epilepsy. However, all GABAa allosteric modulator drugs produce sedation as a side effect of their therapeutic action. Some drugs have a large protective index, which means that the dose required to produce the anticonvulsant effect is much lower than the dose required to produce sedation. Other drugs have a low protective index and must be dispensed with a warning about daytime sedation.

The spreadsheet has two sets of EC_50 and Emax cells for you to play with in order to move the blue curve onto the blue points and the pink curve onto the pink points. When you have aligned the curves with their respective data points, the value of Protective Index will be shown in cell F8. Drug A is shown with square symbols and Drug B is shown with triangle symbols.

9. What is the protective index of Drug A?
3.3 10 20 40

10. What is the protective index of Drug B?
1 5 17 25

11. Which drug is the most potent?
Drug A Drug B

12. Is potency always the most important consideration in selecting a drug for therapeutic use?
Yes No

13. How long did it take you to complete the entire Self-Study page, including downloading information and completion of the test?
30 min. 1 hr. 2 hr. more than 2 hr.

If you complete the test with a 70% score or better Dr. Adams will add 6 points to your grade at the end of the semester.

Questions? Comments?