Diagram of ouabain/EO-regulated α2 Na+ pump-modulated Ca2+ signaling at the plasma membrane (PM)-sarco(endo)plasmic reticulum junction (PLasmERosome). EO reduces Na+ extrusion by the α2 Na+ pump, thereby increasing local [Na+] in the junctional space (JS) and reducing Ca2+ extrusion by the Na/Ca exchanger (NCX). This enhances Ca2+ signaling and, in arterial smooth muscle, contraction. PMCA, PM Ca2+ pump; ATP, adenosine triphosphate; ADP, adenosine diphosphate; Pi, inorganic phosphate; GPCR, G protein-coupled receptor; AR, agonist receptor; GP, G protein; PLC, phospholipase C; IP3, inositol 1,4,5-trisphosphate; IP3R, IP3, receptor; DAG, diacylglycerol; ROC, receptor-operated channel, and SOC, store-operated channel [both composed of transient receptor potential cation channel (TRPC) proteins]; SERCA, sarco(endo)plasmic reticulum Ca2+ ATPase pump; ECF, extracellular fluid; SR, sarcoplasmic reticulum; RyR, ryanodine receptor. Revised from Blaustein and Wier (25).