Final answer:
The Sodium-Calcium Exchanger (NCX) is mainly responsible for the extrusion of calcium ions from the cytoplasm in vascular smooth muscle. It uses energy from sodium's electrochemical gradient, classifying it as secondary active transport, contrasted with SERCA which pumps calcium into the SR.
Step-by-step explanation:
The transporter primarily responsible for extruding calcium ions from the cytoplasm in vascular smooth muscle, thereby contributing to calcium regulation, is the Sodium-Calcium Exchanger (NCX). This mechanism of calcium ion transport is considered secondary active transport because it utilizes the energy from the electrochemical gradient of sodium moving into the cell to drive the extrusion of calcium against its own gradient. The ATP-dependent process that actively transports calcium ions into the sarcoplasmic reticulum (SR) is performed by the Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA), which is a different mechanism of maintaining calcium homeostasis in muscle cells.