Final answer:
L-DOPA enters the blood-brain barrier using L-type amino acid transporters (LAT1), a process essential for allowing this therapeutic agent to reach the central nervous system.
Step-by-step explanation:
L-DOPA, or levodopa, uses L-type amino acid transporters (LAT1) to enter the blood-brain barrier (BBB). LAT1 is a sodium-independent transporter that facilitates the uptake of large neutral amino acids and certain amino acid-derived drugs into the brain.
Since L-DOPA is structurally similar to these amino acids, it can be transported into the brain via LAT1. This transporter is essential due to the selective nature of the BBB, which only allows specific types of molecules, including amino acids, to actively enter the central nervous system (CNS).