Actions of bradykinin include all of the following, except
**Core Concept**
Bradykinin is a peptide involved in the kinin-kallikrein system, which plays a crucial role in the regulation of blood pressure, inflammation, and pain. It is a potent vasodilator and also stimulates the release of histamine and other mediators from mast cells.
**Why the Correct Answer is Right**
Bradykinin's actions include vasodilation, which leads to a decrease in blood pressure. It also stimulates the release of prostaglandins and leukotrienes, which contribute to inflammation. Additionally, bradykinin causes smooth muscle contraction in the bronchi and uterus, leading to bronchoconstriction and uterine contractions. These effects are mediated through the B2 receptor, which is a G-protein coupled receptor.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because bradykinin does not cause vasoconstriction; instead, it causes vasodilation.
* **Option B:** This option is incorrect because bradykinin does not stimulate the release of insulin; it does not have a direct effect on glucose metabolism.
* **Option C:** This option is incorrect because bradykinin does not cause an increase in heart rate; it can actually lead to a decrease in heart rate due to its vasodilatory effects.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that bradykinin's effects are mediated through the B2 receptor, which is a G-protein coupled receptor. This receptor is also involved in the regulation of pain and inflammation.
**Correct Answer: A.**