Lab3

Question 1

What type of animal is used for obtaining tracheal segments in this experiment?

Answer 1

Male Wistar rats

Question 2

What is the purpose of the mini tissue organ bath system (miniTOBS)?

Answer 2

To mount rat isolated tracheal segments for experimentation

Question 3

What physiological solution is used in the miniTOBS?

Answer 3

Krebs solution

Question 4

What is the resting tension adjusted to after suspending the preparations in the tissue bath?

Answer 4

Approximately 300 mg

Question 5

What is the spasmogen usually used to test the viability of the preparations?

Answer 5

Carbachol

Question 6

What is the final bath concentration of carbachol added to produce a submaximal contraction?

Answer 6

0.2 µM

Question 7

What happens to preparations that do not contract to carbachol or contract weakly (<500 mg above baseline)?

Answer 7

They are deemed unviable and discarded

Question 8

How many cumulative concentration-response curves (CCRC) to carbachol must each group complete?

Answer 8

Four CCRCs

Question 9

Fill in the blank: The first CCRC to carbachol is conducted with _______.

Answer 9

No antagonist

Question 10

What should students do with the tissue preparations after the completion of the first CCRC?

Answer 10

Wash and rest the preparation until baseline tension returns

Question 11

What is the purpose of the dosing regimen for a CCRC?

Answer 11

To detail the volumes and concentrations of carbachol needed

Question 12

True or False: Students can prepare drug solutions individually.

Answer 12

False

Question 13

What method is used to calculate the required volume of stock solution to achieve a final concentration in the bath?

Answer 13

C1V1 = C2V2

Question 14

What is the final bath concentration after the first addition in the CCRC?

Answer 14

1x10-8 M

Question 15

What is the concentration of carbachol added for the second step in the CCRC?

Answer 15

1x10-7 M

Question 16

What type of antagonist is used in the second CCRC?

Answer 16

Low dose antagonist

Question 17

What must students do before adding their serial dilutions to the bath?

Answer 17

Check with demonstrators that they have prepared them correctly

Question 18

What is the incubation time after adding the required amount of antagonist?

Answer 18

15 minutes

Question 19

What is the final concentration of carbachol for the fourth CCRC?

Answer 19

1x10-2 M

Question 20

What is the purpose of the wash step after completing each CCRC?

Answer 20

To ensure the preparation is ready for the next experiment

Question 21

Fill in the blank: Gradual loss of sensitivity of the preparations to the drugs is called _______.

Answer 21

Desensitisation

Question 22

What is the role of the class demonstrator in the experiment?

Answer 22

To set up the rat isolated tracheal segments

Question 23

What should be done if the preparations are damaged or not viable?

Answer 23

They should be discarded

Question 24

What is the significance of maintaining a physiological solution during the experiment?

Answer 24

To keep the tracheal segments viable

Question 25

What is indicated by a plateau in the contraction response to carbachol?

Answer 25

The maximum contraction has been reached

Question 26

What is the source of the physiological salt solution used?

Answer 26

Krebs solution with specific mM concentrations

Question 27

What is the purpose of waiting 15 minutes before starting the second carbachol CCRC in time control groups with no antagonist?

Answer 27

To allow the preparation to stabilize before the next measurement. ## Footnote This is crucial for accurate data collection in experimental protocols.

Question 28

What should be done after constructing a third carbachol CCRC?

Answer 28

Wash three times and rest the preparation until the tension returns to baseline. ## Footnote This ensures that the preparation is ready for the next measurement.

Question 29

What is the next step after adding the required amount of high dose antagonist?

Answer 29

Incubate for 15 minutes and enter the third carbachol CCRC data into the relevant table. ## Footnote This step is essential for data analysis and plotting graphs.

Question 30

What must be completed before leaving the lab according to the instructions?

Answer 30

Complete at least up to page 14 of your worksheet. ## Footnote This allows for clarification on data calculation and entry.

Question 31

What does the contraction (%Cmax) represent in the context of carbachol CCRCs?

Answer 31

The contraction as a percentage of the maximum tension achieved. ## Footnote This is used to quantify the response to carbachol concentration.

Question 32

How is the EC50 value defined?

Answer 32

The concentration of agonist that produces 50% of the maximum response to that agonist. ## Footnote This is a standard measure of agonist potency.

Question 33

What is the relationship between EC50 and pD2 value?

Answer 33

pD2 is the –log EC50. ## Footnote A higher pD2 value indicates greater agonist potency.

Question 34

What is the EC50 value of carbachol as mentioned in the document?

Answer 34

3 x 10-7 M (0.3μM). ## Footnote This value is critical for understanding the potency of carbachol.

Question 35

What is the pD2 value of carbachol?

Answer 35

6.50 (i.e. –log EC50). ## Footnote This reflects the potency of carbachol as an agonist.

Question 36

What fundamental principle underlies Schild plot analyses?

Answer 36

Equal agonist-induced responses in the absence and presence of the antagonist indicate equal receptor occupancies by the agonist. ## Footnote This principle is key for interpreting the effects of antagonists.

Question 37

How are concentration ratios determined in Schild analysis?

Answer 37

By taking the ratios of agonist concentrations that produce the same level of response in the presence and absence of the antagonist. ## Footnote This method allows for accurate assessment of antagonist effects.

Question 38

What is the EC50 value for carbachol in the absence of antagonist as mentioned in the example?

Answer 38

5x10-7M. ## Footnote This value is used to compare the effects of antagonist concentrations.

Question 39

What tension level corresponds to 50% of Cmax in the example provided?

Answer 39

600 mg (which is 50% of Cmax of 1200 mg). ## Footnote This is important for determining the effectiveness of carbachol concentrations.