Figure 4.

Role of K⁺‐Cl⁻ cotransport in arterial VSMCs

Ion transport systems shown correspond to KCC3, Ca²⁺‐activated Cl⁻ channel (CACC), SLC8A1 (Na⁺/Ca²⁺ exchanger or NCX type 1), L‐type voltage‐sensitive Ca²⁺ channel (Ca_v1) and SLC4A1 or SLC26A7. Increased KCC3 activity promotes Cl⁻ entry (or decrease Cl⁻ exit) through CACC and, secondarily, anion exchange by SLC4A1 or SLC26A7. It should therefore decrease membrane potential as well as intracellular pH, and thereby stimulate Na⁺/Ca²⁺ exchange by NCX1 and inhibit Ca²⁺ movement through Ca_v1. The end‐result of increased KCC3 activity should thus be a decrease in [Ca²⁺]_i and, secondarily, in myogenic tone.