The modeling method in pathophysiology

Significance of modeling and experimental therapy

Pathophysiology serves as a fundamental base for clinical disciplines. To understand how exactly a disease arises and progresses, the modeling method is used. It makes it possible to artificially recreate a pathological state, and to analyze in detail its etiology (causes and conditions of development) and pathogenesis (mechanisms of development).

An essential component of this approach is experimental therapy. It allows not only observing the dynamics of an artificially induced disease, but also testing new treatment methods.

At the same time, extrapolating data obtained in an experiment to humans requires extreme caution. For a competent interpretation and subsequent translation of the results, a comparative evolutionary approach is applied. Both the capabilities and strict limitations of the method are always taken into account, as well as moral and ethical standards when working with laboratory animals. Research on humans has even stricter frameworks and relies on deontological aspects.

Equipment and basic skills for the experiment

For the correct reproduction of diseases, a researcher must master a complex set of practical skills. These include skills in restraining experimental animals, calculating and administering anesthesia, blood sampling, and parenteral administration of various solutions.

Material support for experimental work traditionally includes:

• Laboratory animals (rats, mice, frogs, rabbits).
• Special restraining devices for secure fixation.
• Syringes, anesthetic solutions, and antiseptics for treating surgical wounds.
• Sets of surgical instruments (scissors, forceps, etc.).

As theoretical support, computer control programs, control questions, and presentations are used.

Methods of anesthesia and working with animals

The method of pain relief strictly depends on the species of the animal. In practice, the following verified techniques are used:

1. Mouse: 0.20 ml of a 1.00% hexenal solution is administered subcutaneously.
2. Frog: 0.50 ml of a 20.00% urethane solution is used, injected under the skin of the back.
3. Rat: inhalation ether anesthesia is used.

To assess the state of the body against the background of the simulated pathology, blood analysis or the administration of additional substances is often required. To a rat, 0.40 ml of saline can be administered via various routes: intravenously, intraperitoneally, intramuscularly, or subcutaneously.

Blood sampling also has its characteristics: 0.20 ml is taken from the tail vein in rats, whereas 0.50 ml is taken from the marginal ear vein in rabbits.

Surgical modeling: splenectomy

One example of surgical intervention in modeling is the removal of the spleen (splenectomy) in a rat. The procedure is strictly regulated and consists of the following stages:

• The skin on the animal's abdomen is thoroughly treated with alcohol or iodine.
• Using scissors, an incision 3.0–4.0 cm long is made along the midline of the abdomen.
• The aponeurosis is carefully incised, and the peritoneum is opened.
• In the left hypochondrium, the researcher locates the spleen.
• Blood vessels supplying the organ are ligated, after which the spleen is removed.
• The surgical wound is sutured in layers (muscles first, then skin).
• In conclusion, the suture area is re-painted with iodine to prevent infections.

Class and exam questions

What else to study on this topic

• Main historical stages in the development of pathophysiology and the contribution of domestic scientists
• The concept of norm, pre-disease, and characteristics of typical pathological processes
• The role of causes and conditions in the onset of diseases (polyetiology)
• The main link of pathogenesis and the formation of "vicious circles"
• Pathophysiological foundations of resuscitation and terminal states (agony, clinical death)

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.