Experiments on the effect of toxaphene on the action of acetylcholine
Experiments on the effect of toxaphene on the action of acetylcholine
The purpose of this experiment was to learn the experimental conditions for studying the quantitative and qualitative effects of drugs. To observe the effects of different concentrations of acetylcholine on the rectus abdominis muscle of isolated toads. To observe the effect of toxaphene on the action of acetylcholine as well as to learn the method of plotting the cumulative dose effect curve.
Operation method
direct comparison method
Materials and Instruments
Toad, Rectus abdominis Move 1. Connect the experimental setup and ensure the experimental conditions. For more product details, please visit Aladdin Scientific website.
Acetylcholine chloride Physosti gmine salicylic
Magnus experimental set XWTD204 Benchtop automatic balance recorder Carrier amplifier Force displacement transducer Air pump Surgical instruments Water bath tube Support table
2. Conditions of the recording device: Set the range knob of the bench-top balance recorder at 5 mv, open the recording pen and adjust the pen to the appropriate position for recording. Take 2 g weights hanging in the transducer hook, adjust the carrier amplifier "gain", "zero" knob, so that the recording pen up 1 large frame (25 mm), remove the weights, the recording pen to the original position (plus weights when adjusting). (adjust the "Gain" knob when adding weights and the "Zero" knob when removing weights, repeat as many times as necessary). The recording speed is 8 mm/min.
3. Specimen preparation: Destroy the brain and spinal cord of the toad, fix it on the frog plate in dorsal position, cut open the abdominal skin, ligate the tendons of the right and left rectus abdominis muscles at the upper end of the pubic bone with a small tweezers, cut off the tendon at the lower part of the ligation, and then cut it upward along the white line of the abdominal wall (the abdominal vein on the inner side of the abdominal wall should be avoided to be cut off) in order to separate the left and right rectus abdominis muscles, then cut it upward along the external edge of the rectus abdominis muscle, and then ligate it at the height of the second tendon stroke with a line. The rectus abdominis muscle was ligated with a line at the height of the second tendon and the muscle was cut above the ligature line. The specimen is washed with Ringer's solution and placed in a beaker of Ringer's solution.
The reason for choosing the rectus abdominis muscle of the toad is that it is more sensitive to acetylcholine, which makes it easier to compare the height of contraction with that of the toad because of its gentler and more stabilizing effect.
4. Suspension of the specimen: One end of the rectus abdominis muscle specimen is fixed at the bottom of the bath tube, and the other end is suspended on a small hook of the force displacement transducer. The tension changes in the rectus abdominis muscle are recorded on a bench-top balance recorder by means of a force-displacement transducer and a carrier amplifier. Immediately after hanging the specimen, the fluid is changed once and the rectus abdominis muscle specimen is preloaded with 2 g (25 mm for a 1-gig rise) and stabilized for 30 min before dosing.
5. Dosing method: according to the cumulative method, first observe the quantitative and effective relationship between the contraction of the rectus abdominis muscle of toads with each concentration of acetylcholine, the order of dosing is shown in Table 4-8, then rinse, first rinse 4-5 times, then change the fluid every 10 minutes, after the rectus abdominis muscle specimen is back to the baseline (about 40 minutes), add 10-3 mol/L Physosti gmine 0.5 mol/L Physosti gmine (toxapheneine). （After the rectus abdominis muscle specimen is restored to baseline (about 40 minutes), add 10-3 mol/L Physosti gmine 0.1 ml, and after 15 minutes of action, add various degrees of acetylcholine according to the cumulative method of administration, and observe the effect of Physosti gmine on the quantitative and effective relationship of acetylcholine, and the order of administration is shown in Table 4-9.
6. Plotting the quantitative effect curve: take the maximum height of contraction induced by acetylcholine as 100%, calculate the percentage of contraction of rectus abdominis muscle by each concentration of acetylcholine. Calculate the percentage of contraction of rectus abdominis muscle for each concentration of acetylcholine: 
The potency curves were plotted using the percentage of contraction as the vertical coordinate and the negative logarithm of the acetylcholine concentration as the horizontal coordinate (curve A: potency curve of acetylcholine contraction of the rectus abdominis muscle of the toad, curve B: potency curve of acetylcholine contraction of the rectus abdominis muscle of the toad after toxocarpine pretreatment).