Experiments on the antihypertensive action of antihypertensive drugs

Summary

Characterization of the hypotensive effect of sodium nitroprusside and propranolol in anesthetized animals.

Operation method

common carotid artery cannulation

Principle

Sodium nitroprusside and propranolol are non-selective vasodilators and β-adrenergic receptor blockers respectively, which have the effect of lowering blood pressure, but the characteristics of blood pressure lowering and clinical application of the two drugs are different. The common carotid artery was intubated and connected to a recorder to record the changes in blood pressure of rabbits before and after the administration of the drugs, so as to observe the differences in the antihypertensive characteristics of the drugs and to provide a theoretical basis for the rational application of the drugs in clinical practice.

Materials and Instruments

Rabbit
Pentobarbital sodium solution; heparin solution; sodium nitroprusside injection; naproxen solution
Scissors; surgical instruments; syringes; tracheal tube; arterial clips; arterial cannulae; venous cannulae; BL-420 Bio-signal Recorder; blood pressure transducer; silk threads; beakers, etc.

Move

1. A rabbit was taken, weighed, anesthetized with 3% pentobarbital sodium solution 30 mg/kg intravenously, fixed on the rabbit table in supine position, the rabbit hair on the neck was clipped, the skin of the neck was incised centrally, and the trachea and bilateral common carotid arteries were carefully separated. The trachea was incised and a tracheal tube was inserted and fixed.

2. The right common carotid artery was threaded under the right common carotid artery in preparation for lifting the blocked blood flow to measure the ascending reflex. Clip an arterial clip on the proximal end of the left common carotid artery to block blood flow, and then insert a heparin-filled arterial cannula into the common carotid artery toward the heart for blood pressure monitoring, and connect the blood pressure transducer to the BL-420 biosignal recorder.

3. Separate the femoral vein on one side, insert the venous cannula, and connect the infusion bottle to supply medication and fluid.

4. Open the arterial clip and trace a section of normal blood pressure curve. After stabilization of blood pressure, the following experiments were performed in turn and the similarities and differences in drug effects were compared.

Lift the right common carotid artery to block blood flow for 15 s. Repeat the procedure after 2 min and record the blood pressure curve.

After the blood pressure was stabilized, sodium nitroprusside was injected intravenously at a rate of about 30 drops/min, and the changes in blood pressure were observed and recorded. After the blood pressure dropped to a stable level for 5 min, stop the drug and observe the recovery of blood pressure.

After the blood pressure of rabbits returned to normal and stabilized, 0.5% propranolol solution 0.5 mg/kg was injected intravenously, and the curve of blood pressure changes was observed and recorded.

5. Plot the blood pressure change curve according to the experimental results.

Caveat

1. Do not irritate the nerves when separating the vessels during the procedure.

2. The transducer piping system should be filled with heparinized saline and drained of air bubbles before connection.

3. sodium nitroprusside is unstable and decomposes easily when exposed to light, so the outside of the infusion bottle should be wrapped with tin foil.

Common Problems

1. What are the differences in the antihypertensive effects and mechanisms of action of sodium nitroprusside and propranolol?

2. For what conditions can sodium nitroprusside and propranolol be used to lower blood pressure and what are the precautions for their use?

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