Ca²⁺-Driven Selectivity of the Effect of the Cardiotonic Steroid Marinobufagenin on Rabbit Sinoatrial Node Function.

ABSTRACT: The synergy between Na⁺-K⁺ pumps, Na⁺-Ca²⁺ exchangers, membrane currents and the sarcoplasmic reticulum (SR) generates the coupled-clock system, which governs the spontaneous electrical activity of heart sinoatrial node cells (SANCs). Ca²⁺ mediates the degree of clock coupling via local Ca²⁺ release (LCR) from the SR and activation of cAMP/PKA signaling. Marinobufagenin (MBG) is a natural Na⁺-K⁺ pump inhibitor whose effect on SANCs has not been measured before. The following two hypotheses were tested to determine if and how MBG mediates between the Na⁺-K⁺ pump and spontaneous SAN activity: (i) MBG has a distinct effect on beat interval (BI) due to variable effects on LCR character

SUBMITTER: Segal S 

PROVIDER: S-EPMC10378090 | biostudies-literature | 2023 Jul

REPOSITORIES: biostudies-literature