After the frog's heart is isolated, a frog heart cannula containing Ren's fluid is inserted into the ventricle, and this artificial perfusion method is used to keep the heart metabolism running smoothly in order to maintain the frog's heart contracting and diastole rhythmically. The heart beats were recorded by a biosignal processing system. In this experiment, isolated frog hearts were used to observe the cardiotonic effect of cardiac glycosides.
Operation method
artificial irrigation
Principle
After the frog's heart is isolated, a frog heart cannula containing Ren's fluid is inserted into the ventricle, and this artificial perfusion method is used to keep the heart metabolism running smoothly in order to maintain the frog's heart contracting and diastole rhythmically. The heart beats were recorded by a biosignal processing system. In this experiment, isolated frog hearts were used to observe the cardiotonic effect of cardiac glycosides.
Materials and Instruments
Frog Move I. Methodology Caveat ⒈ The frog heart is preferred for this experiment. Because the subcutaneous glands of toads have cardiac glycoside-like substances, which can reduce the sensitivity to cardiac glycosides.⒈ The frog heart cannula must be inserted into the ventricle. Do not use too much force and insert too deeply to damage the myocardium.3) When ligating a vein, keep it away from the venous sinus (starting point).When sung, the amount of Ren's solution should be constant and care should be taken to avoid air entering the heart. Mix well with a pipette when adding drugs.Be careful to keep the fluid level in the cannula constant throughout the experiment to ensure a fixed load on the heart.Select The position of the baseline, magnification, and tracing speed should always be the same during the experiment. Common Problems I. What does cardiac glycosides do for the heart? For more product details, please visit Aladdin Scientific website.
Digitalis solution Ren's solution Calcium-free Ren's solution Calcium chloride solution
Bioinformatics Tension transducer Frog plate Probe Awl Surgical equipment Syringe Frog heart cannula Frog heart clip Double concave clip Iron frame Universal lever
⒈ Preparation of the isolated frog heart (Figure 6-1)
(1) Destroy the brain, spinal cord, supine position fixed on the frog plate.
(2) cut open the thorax, pericardium to expose the heart, ligature of the right aorta (A), in the left main A threading spare.
(3) Cut a small "V"-shaped opening in the left main A. Insert the frog heart cannula with Ren's fluid and pass it through the main A ball during cardiac contraction. Turn to the left rear into the ventricle, see the liquid level in the cannula with the heart beat up and down after the loose knot tied tightly and fixed in the cannula of the After seeing the fluid level in the cannula rise and fall with the heartbeat, the loose knot is tightened and fixed to the small hook of the cannula. The blood in the cannula is aspirated with a dropper, and the remaining blood is washed out with 2 to 3 changes of Ren's solution to prevent clots from clogging the cannula. Cut the The aorta is cut, the heart is lifted with the cannula, and the rest of the vessels are ligated together from the venous sinus down (do not injure or ligate the venous sinus), and the surrounding tissues are separated. Separate the surrounding tissue, cut the vessels under the ligature, and dissect out the heart. The blood vessels are cut under the ligature, and the heart is dissected out. The blood vessels are then washed continuously with Ren's solution until they are free of blood, so that The cannula is then washed continuously with Ren's solution until it is free of blood, leaving about 1.5 ml of Ren's solution in the cannula. 
Figure 6-1 Schematic diagram of the insertion points of the straub method (a) and (b).
Preparation of the experimental setup
(1) Fix the frog heart cannula on the iron frame table, use the frog heart clip with a long wire to clamp the apical part of the heart during the diastolic period, and connect the long wire to the tension transducer. energy converter.
(2) Turn on the computer and BL-420 system → Input signals or experimental items → Cyclic experiment (C) → Frog heart perfusion (1).
(3) Start the experiment (start automatic recording at this time) → speed adjustment for 4 or 8s/dir → record the normal curve, tension adjusted to 0.5 ~ 1 g. (The experimental process should not be arbitrary). 1 g. (Do not click the red dot of the recording at random during the experiment, otherwise the recording will be interrupted).
3) Administer the drug in the following order
(1) Trace a section of the normal curve.
(2) Use a dropper to aspirate Ren's solution from the cannula and replace it with an equal volume of calcium-free Ren's solution and observe how the curve changes.
(3) When the heart contraction is significantly weakened, add 0.2 ml of 1:500 digitalis toxin to the cannula, and if the effect is not obvious, add another 0.2 ml of 1:250 digitalis toxin. If the effect is not obvious, then add 1:250 digitalis toxin 0.2 ml.
(4) When the effect is obvious, add 2-3 drops of 1% calcium chloride solution to the cannula. Compare the amplitude and frequency of cardiac contractions after each addition.
Sing the end of the experiment and click "■" to stop the experiment → enter the file name → save → inversion → compression → graphic clip.
⒋ Be careful with Related Content Settings (S) Experiment Title (H) → Experiment Personnel (P) → Experiment Related Data (R).
Select Print Settings File → Print Preview (V) → 4 sheets/group → Print Settings (R) → Properties (P) → Customize (S) Ink saving→Printing (P)→Number of copies printed (C) II. Results
Perform graphical analysis.
II.Analyze the action characteristics of cardiac glycosides from the experimental results.