The reverse mode of the Na⁺/Ca²⁺ exchanger contributes to the pacemaker mechanism in rabbit sinus node cells.

ABSTRACT: Sinus node (SN) pacemaking is based on a coupling between surface membrane ion-channels and intracellular Ca²⁺-handling. The fundamental role of the inward Na⁺/Ca²⁺ exchanger (NCX) is firmly established. However, little is known about the reverse mode exchange. A simulation study attributed important role to reverse NCX activity, however experimental evidence is still missing. Whole-cell and perforated patch-clamp experiments were performed on rabbit SN cells supplemented with fluorescent Ca²⁺-tracking. We established 2 and 8 mM pipette NaCl groups to suppress and enable reverse NCX. NCX was assessed by specific block with 1 μM ORM-10962. Mechanistic simulations were performed by Maltsev-Lakatta minimal computational SN model. Active reverse NCX

SUBMITTER: Toth N 

PROVIDER: S-EPMC9759562 | biostudies-literature | 2022 Dec

REPOSITORIES: biostudies-literature