Study effects of drugs on isolated frog heart.

 Experiment

Object:

 Study effects of drugs on isolated frog heart (Demonstration Studies)

Reference(s): 

1) Kulkarni SK; Handbook of Experimental Pharmacology Third edition 1999; Reprint 2005; Vallabh Prakashan Delhi; page no-155.

                   

2) K.D.Tripathi. Essentials of Medical Pharmacology, Sixth edition 2008 JAYPEE, Brothers Medical Publishers (P) Ltd, New Delhi; page no-476.

Requirement: 

Animal: Frog                    

Chemicals: 

Adrenaline (stock solution 10 µg/ml), Noradrenaline (stock solution 10µg/ml), Acetylcholine (stock solution 10 µg/ml), Calcium chloride (stock solution 10 mg/ml), Potassium chloride (stock solution 10 mg/ml), Physiological solution-Frog ringer

Procedure:

1) Pith the frog and pin it to the frog board. Give a midline incision on the abdomen. Remove the pectoral girdle and expose the heart. Carefully remove the pericardium and put a few drops of frog ringer solution over the heart. Trace the inferior venacava, put a thread around it and give a small cut in order to insert the venous cannula which in turn connected to a perfusion bottle containing the frog ringer solution. Insert the cannula in the vein and tie the thread to ensure the cannula in place. Give a small cut in one of the aortae for the perfusate to come out.

2) Add a proper venous pressure of 2-4 cm by altering the height of perfusion bottle. The effective venous pressure is he height in cms from the level of venous cannula and the ringer level in the perfusion bottle. Use of marriots bottle helps in attaining the constant pressure.    State the perfusion by opening screw clamp attached to the tube.

3) Pass a thin pin hook through the tip of the ventricle and with the help of a fine thread attached to the hook, tie it to the free limb of the universal lever, which is fixed to a stand. Adjust proper  tension and magnification by altering the height of the lever. Record the normal contraction of the heart on smoked drum.

4) Inject 0.1, 0.2, 0.5 and 1 ml of the stock solution of each drug in a sequential order and note the change in the rate and amplitude of contraction. Keep at least 5 min gap between the administration of each dose of the drug. The drug is administered by injecting into the perfusion tube very close to the venous cannula. Take precautions to avoid any leakage of the drug from the tube, and the injection of air bubbles.

5) Label and fix the tracing with the fixing solution.

Procedure/Method Followed: 

Procedure should be written by the student only after completion of the experiment in past tense.

Procedure should be written point wise.

Precautions:

1) Syringe should be washed before injecting each drug.

2) Drugs should be injected near to the cannula. Over perfusion should be avoided.

3) Heart must be kept wet by continuously pouring ringer solution.

4) No air bubbles must be present in the tube. Heart should not be injured.

Observation Table 

Result:

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