Experiment : Effects of drugs on frog oesophagus
Equipment
Animal:
- Frog (Rana hexadactyla)
Drugs & Solution:
- Acetylcholine 10%
- Physostigmine 10%
- Atropine 0.1%
- Frog Ringer
Equipment:
- Poppy seeds
- Frog board
- Stop watch
- Pithing Needle
- Cotton swab
- Dissecting tray (wax board)
- Pins
Experiment
First you select a frog
Select a drug and drag the dropper to the oesophagus to instill
Drag and place a poppy seed above the cephalic end of the oesophagus
Select the Start button to turn on the stopwatch when the seed crosses the cephalic end of the oesophagus. Select the Stop button when the seed reaches the distal end the oesophagus
Note down the time taken for the poppy seed to move from cephalic end to distal end of the oesophagus in observation tab.
Ringer
Acetylecholine
Physostigmine
Atropine
Drug Acting :
Seed Acting :
00
Sec.
| Frog No. | Drug | Reading |
|---|---|---|
| Frog Not Selected | ||
| Drug | Reading 1 | Reading 2 | Reading 3 | Average |
|---|---|---|---|---|
| Ringer | ||||
| Acetylcholine | ||||
| Ringer | ||||
| Physostigmine | ||||
| Ringer | ||||
| Atropine | ||||
| Ringer | ||||
| Atropine + Acetylcholine |
Procedure
A frog is pithed by destroying its spinal cord
The lower jaw is removed.
The oesophagus is slit open from the buccal cavity to the stomach.
The oesophagus is everted to fix it on a wooden board with pins.
The pins must be fixed such that the distance between the pins is 1 cm.
Blood is wiped away with a cotton swab dipped in frog ringer solution.The surface is moistened with frog ringer. Place a poppy seed on the oesophagus and start the stop-watch when it crosses the pin at the cephalic end. Stop the watch when the seed reached the pin at the caudal end. Note the time taken for the seed to travel the distance between the pins Test each drug including ringer thrice and calculate the average reading for each drug.
Objectives
Objectives
To find out the effect of drugs on the ciliary motility of frog oesophagus.
Precautions
- The distance the seed travels should be approximately 1 cm. The pins must be fixed such that the distance between the start point and end point is 1 cm.
- The surface of the oesophagus should be wiped frequently with a cotton swab soaked in ringer to remove mucus.
- Wiping should be gentle and the direction of wiping is from cephalic end to caudal end. Otherwise the cilia may get damaged.
- The surface of the oesophagus should be moistened with ringer frequently so that the tissue does not dry up and die.
- The surface should not be flooded with the ringer. The seeds will start floating and will not move since cilia cannot reach them.
- Test each drug including ringer thrice and calculate the average reading for each drug.
- Take separate control readings for each drug i.e. before testing any drug, take readings with ringer.
- Use new frog for each drug. To observe interactions, drugs should be applied on the same frog consecutively without using ringer in between them.
