Experimental effects of efferent nervous system drugs on blood pressure and hemodynamics
Efferent nervous system drugs produce cardiovascular effects by acting on the corresponding receptors on cardiac and vascular smooth muscle, resulting in corresponding changes in blood pressure, heart rate and myocardial contractility. In this experiment, the effects of adrenergic receptor agonists and antagonists and cholinergic receptor agonists and antagonists were analyzed by observing the changes in blood pressure and hemodynamics in animals.
Operation method
Acute blood pressure recording method
Materials and Instruments
Rabbit Move 1. Weigh and anesthetize with 3% sodium pentobarbital (30 mg/kg) intravenously into the ear margins (injection should not be too rapid as it may cause paralysis of the respiratory muscles). For more product details, please visit Aladdin Scientific website.
Sodium pentobarbital Heparin Epinephrine Norepinephrine Isoprenaline Phentolamine Propranolol Saline
Powerlab Pressure transducer Surgical instruments Tracheal intubation Arterial intubation Arterial clamps Venous cannulae Cardiac catheters Syringes Rabbit table Silk threads Yarns
2. Fix the rabbit in the dorsal position on the operating table, and cut off the hair in the groin on both sides. At the place where the femoral artery pulsation is obvious, cut the skin longitudinally along the direction of the femoral artery and vein for about 3-4 cm, separate the right femoral artery and thread it for spare (for observation of BP); and separate the left femoral vein and thread it for spare (for intravenous drug administration).
3. Cut off the hair of the neck, incise the skin of the neck in the middle, isolate the right common carotid artery, and thread it (try to isolate a longer section for observation of LVP after retrograde intubation).
4. Turn on the Powerlab and pre-fill the transducer with heparin (pay attention to exhausting air bubbles; familiarize yourself with the direction of the three-way tube).
5. Heparinization: femoral vein cannulation, 0.5% heparin injection (1 ml/kg).
6. femoral artery cannulation, observe and record BP.
7. retrograde common carotid artery cannulation, observe and record LVP, LVP/dt. When the catheter has been inserted for a certain length of time (the approximate length of entry of the catheter can be assessed externally prior to cannulation), maneuver carefully. When the catheter enters the ventricle, there is a sensation of a breakthrough and a sensation of emptying, and the blood pressure waveform changes to an intraventricular pressure waveform (lower diastolic blood pressure, higher systolic blood pressure, higher overall pulse pressure, and a waveform amplitude that is significantly higher than that of the arterial blood pressure waveform. (See schematic below). 
Note: If the insertion is a little shallow, it is easy to be washed out of the heart by the blood flow, and the waveform will return to the arterial blood pressure waveform; if the insertion is too deep, it will not be able to record the waveform if it is blocked on the ventricular wall, or even puncture the heart. Therefore, the operation should be combined with the in vitro estimation of the length, feel and the change of blood pressure waveform for judgment.
8. Observe and record a normal graph.
9. Administer and observe and record the medication:
① Adrenaline (Adr) → Norepinephrine (NA) → Isoproterenol (Iso) → Phentolamine, 5 minutes later → Norepinephrine → Adrenaline → Isoproterenol is given again.
② Adrenaline → norepinephrine → isoprenaline → propranolol (0.5 ml/kg), 5 min later → isoprenaline → adrenaline → norepinephrine.
Note: 0.2 ml/kg for all except propranolol; saline may be injected after each administration . , inject the dead space into the vein; after each administration, wait for BP to stabilize before giving another drug.