Which of the following statement about Bradykinin is true?
**Core Concept**
Bradykinin is a potent vasodilator and a key player in the kinin-kallikrein system, which plays a crucial role in blood pressure regulation and inflammation. It is a peptide that is formed from the cleavage of kininogen by the enzyme kallikrein.
**Why the Correct Answer is Right**
Bradykinin exerts its effects by binding to bradykinin receptors, specifically B1 and B2 receptors, which are G-protein coupled receptors. This binding causes an increase in intracellular calcium levels, leading to smooth muscle relaxation and vasodilation. Additionally, bradykinin stimulates the release of prostaglandins and histamine, which further contribute to its vasodilatory and inflammatory effects. The kinin-kallikrein system is also involved in the regulation of blood pressure through its effects on the renin-angiotensin-aldosterone system.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because bradykinin is not primarily involved in the regulation of cardiac output.
**Option B:** This option is incorrect because bradykinin's effects on blood pressure are not primarily mediated through its effects on the sympathetic nervous system.
**Option C:** This option is incorrect because bradykinin's effects on inflammation are not primarily mediated through its effects on the coagulation cascade.
**Clinical Pearl / High-Yield Fact**
The kinin-kallikrein system plays a critical role in the pathophysiology of hypertension, and inhibitors of this system, such as ACE inhibitors, are commonly used to treat hypertension.
**Correct Answer: C. Bradykinin stimulates the release of prostaglandins and histamine, leading to vasodilation and inflammation.**