Final answer:
Adenosine and prostaglandins induce vasodilation in vascular smooth muscle in response to increased carbon dioxide levels in the myocardium, increasing the blood flow to match the metabolic demand.
Step-by-step explanation:
Adenosine and prostaglandins are substances in the body that have a role in regulating blood flow and blood pressure. When there is an increased level of carbon dioxide in the myocardium, it is a signal that the muscle is metabolically active and requires more oxygen. In response, adenosine and prostaglandins cause vasodilation, which is the widening of blood vessels, to increase blood flow to the area.
As part of the body's local autoregulation mechanism, adenosine is known to induce vasodilation. Additionally, prostaglandins, although capable of inducing smooth muscle contraction, also have the ability to lower blood pressure, contributing to vasodilation under certain conditions such as the presence of increased carbon dioxide. Therefore, the final answer to the question is that adenosine and prostaglandins act on vascular smooth muscle to cause vasodilation when the myocardium has increased levels of carbon dioxide.