Experimental effects of efferent nervous system drugs on blood pressure in anesthetized dogs

Summary

Using a direct blood pressure measurement method, an arterial cannula inserted into the common carotid artery and a pressure transducer form an anticoagulant closed system, and blood pressure values can be read from the BL-420 system connected to the pressure transducer to observe the effects of adrenomimetic drugs on canine blood pressure, as well as the effects of receptor blockers on their action. The site of action is analyzed.

Operation method

direct blood pressure (DBP) measurement

Principle

Using a direct blood pressure measurement method, an arterial cannula inserted into the common carotid artery and a pressure transducer form an anticoagulant closed system, and the blood pressure value can be read from the BL-420 system connected to the pressure transducer.

Materials and Instruments

Dogs
Sodium pentobarbital Heparin Saline Epinephrine hydrochloride Norepinephrine bitartrate Isoproterenol Cardioplegia Phentolamine Injection
Operating table Biological collection system Artificial respirator Coarse scissors Surgical scissors Iris scissors Iris forceps Surgical forceps Scalpel Vascular forceps Canine arterial trocars Venous trocars Tracheal trocars Beakers Syringes Surgical threads Gauze

Move

First, 200 ± 20 g SSD rats were anesthetized with 3% pentobarbital sodium 1 ml/kg in the small saphenous vein of the hind limbs, fixed in the supine position on the operating table, and the following operations were performed:
⒈ tracheal intubation: cut the skin about 5 cm in the midline of the neck, separate the muscles on both sides with hemostatic forceps, expose the trachea, put a thin line under the trachea, lift the trachea, and then cut the skin. Trachea under a thin line, lift the trachea, make a (⊥)-shaped incision, insert a Y-shaped tracheal tube in the direction of the lungs, and secure it with a thin line. Fix it with a thin wire and use it for respiratory ventilation.
Pake carotid artery intubation: find the carotid artery sheath according to the arterial pulsation, separate the tissues around the common carotid artery and the vagus nerve, make it free. Separate it from the carotid sheath according to the arterial pulsation, separate the tissues around the common carotid artery and vagus nerve, make it free, and put two wires under it, ligate the distal end, clip the proximal end with arterial clips, and cut a "V" in the direction of heart at the proximal knot. A "V" incision is made at the proximal knot, a heparin-filled arterial cannula is inserted, ligated and fixed, and connected to the BL-420 BioAcquisition System.
Femoral vein cannulation: In the groin, where the femoral artery pulsation was touched, the skin was incised longitudinally for 3 cm, the femoral vein was separated, and two threads were threaded underneath the femoral vein, and the femoral vein was removed distally. The femoral vein was isolated and two threads were threaded underneath the femoral vein and ligated at the distal end. A "Λ" incision was made at the knot in the direction of the heart and a saline-filled venous cannula was inserted. A saline-filled intravenous cannula is inserted and secured with a ligature for infusion of fluids and medications. After the above operation, release the arterial clip and observe the blood pressure and drug administration.
Sing the following drugs sequentially from the vein, observe the changes in blood pressure, and consider the rationale for the changes.
(1) Observe the effect of adrenomimetic drugs:
① Epinephrine hydrochloride 0.1 mg/kg
② norepinephrine bitartrate 0.1 mg/kg
(iii) Isoprenaline 0.05 mg/kg.
(2) Observe the effect of the application of the α-blocker phentolamine on the action of the adrenomimetic drug:
① Phentolamine 0.1 mg/kg was injected slowly, and the following drugs were administered 2-3 minutes after administration:
② epinephrine hydrochloride 0.1 mg/kg
③ Norepinephrine bitartrate 0.1 mg/kg
④ Isoprenaline 0.05 mg/kg
(3) Observe the effect on the action of the sympathomimetic epinephrine drug after application of the β-blocker, cardioplegia:
① 1% cardiac glycosides 0.1 mg/kg was injected slowly, and the following drugs were administered 5-10 minutes after the drug was administered:
② epinephrine hydrochloride 0.1 mg/kg
③Norepinephrine bitartrate 0.1 mg/kg
④Isoproterenol 0.05 mg/kg
II. Results

Caveat

⒈ into the arterial catheter, do not pull the artery, so as not to damage the lining caused by coagulation. After the cannula is inserted, it is necessary to make the cannula and the common carotid artery in a straight line, otherwise the tip of the cannula can poke the artery and cause massive bleeding.The cannula should be at the same level as the heart.3. If the dog gradually awakens during the experiment, add another 1/4 of the original anesthetic dose.

Common Problems

I. What are the effects of epinephrine, norepinephrine, and isoprenaline on blood pressure and heart rate? How do they work? What are their clinical uses? What drugs are prone to produce arrhythmias?

What are the changes in blood pressure after the use of α-blocker phentolamine and then adrenomimetic drugs? What is the rationale for this?

(c) What is the change in blood pressure after the use of beta-blocker cardioplegia and then adrenomimetic drugs? What is the rationale for this?

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