Which physiologic effect is NOT associated with histamine?

In the context of histamine's physiological effects, increased cardiac contractility is not a typical reaction associated with histamine release. Histamine is primarily known for its role in inflammatory responses and allergic reactions.

When histamine is released, especially during an allergic reaction or anaphylaxis, it can cause severe bronchoconstriction, leading to difficulties in breathing. This is particularly significant in conditions such as asthma or anaphylactic shock.

Histamine also plays a key role in systemic vasodilation, which results in a decrease in blood pressure and can contribute to symptoms like dizziness or fainting. This vasodilation is a part of the body's response to inflammation.

Increased vascular permeability is another well-known effect of histamine. This occurs when blood vessels become more permeable, allowing proteins and white blood cells to pass through the vessel walls to the site of an injury or infection, which is essential for an effective immune response.

In contrast, histamine does not promote increased cardiac contractility. While it may have some effect on heart rate and vascular resistance, its primary roles are related to respiratory and vascular responses rather than directly enhancing the force of heart muscle contractions.