Sarcoplasmic Reticulum Ca²⁺ Release Uses a Cascading Network of Intra-SR and Channel Countercurrents.

ABSTRACT: In muscle, Ca²⁺ release from the sarcoplasmic reticulum (SR) into the cytosol is mediated through the ryanodine receptors (RyRs) and sustained by countercurrents that keep the SR membrane potential near 0 mV. Likewise, Ca²⁺ reuptake by the sarco/endoplasmic reticulum Ca²⁺ ATPase pump requires countercurrent. Although evidence has suggested that TRIC K⁺ channels and/or RyR K⁺ influx provide these countercurrents, the exact sources have not yet been determined. We used an equivalent circuit compartment model of a cardiac SR, the surrounding cytosol, and the dyadic cleft to probe the sources of countercurrent during a complete cardiac cycle. By removing and relocating TRIC K⁺ channels, as well as limiting when they are active,

SUBMITTER: Zsolnay V 

PROVIDER: S-EPMC5984985 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature