Which effect does adrenaline have on capillary permeability during anaphylaxis?

• A. Increases permeability
• B. Decreases permeability
• C. No effect on permeability
• D. Variable effect depending on dosage

Answer: (B)

Adrenaline, also known as epinephrine, has several important effects on the body during anaphylaxis, particularly regarding capillary permeability. In cases of anaphylaxis, there is a sudden release of inflammatory mediators such as histamine, which can increase capillary permeability, leading to symptoms such as swelling, hives, and potentially life-threatening edema.

When adrenaline is administered, it acts to counteract these effects. One of its primary functions is to cause vasoconstriction, which helps to reduce blood flow to areas affected by allergic reactions. As a result, adrenaline decreases capillary permeability, helping to stabilize blood vessel integrity and prevent the fluid from leaking out into surrounding tissues. This mechanism is crucial in reversing the shock state and mitigating the symptoms of anaphylaxis.

Additionally, adrenaline enhances heart function and bronchodilation, further aiding in the acute management of anaphylactic reactions. Therefore, the correct assertion that adrenaline decreases capillary permeability is consistent with its pharmacological role in controlling the adverse effects of anaphylaxis.