Intracellular calcium dynamics and acceleration of sinus rhythm by beta-adrenergic stimulation.

ABSTRACT:

Background

Recent evidence indicates that membrane voltage and Ca2+ clocks jointly regulate sinoatrial node (SAN) automaticity. Here we test the hypothesis that sinus rate acceleration by beta-adrenergic stimulation involves synergistic interactions between these clock mechanisms.

Methods and results

We simultaneously mapped intracellular calcium (Ca(i)) and membrane potential in 25 isolated canine right atrium, using previously described criteria of the timing of late diastolic Ca(i) elevation (LDCAE) relative to the action potential upstroke to detect the Ca2+ clock. Before isoproterenol, the earliest pacemaking site occurred in the inferior SAN, and LDCAE was observed in only 4 of 25 preparations. Isoproterenol infusion (1 micromol/L) increased sinus rate and shifted pace

SUBMITTER: Joung B 

PROVIDER: S-EPMC2735196 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature