Intracellular calcium does not directly modulate cardiac pacemaker (if) channels

Pflugers Arch. 1991 Dec;419(6):662-4. doi: 10.1007/BF00370312.


A study on the cardiac pacemaker current if in inside-out macro-patches of sino-atrial (SA) node cells has recently demonstrated that if channels are directly activated by intracellular cAMP. Using the same preparation, here we investigate the possibility that internal Ca2+ ions play a role in the modulation of if channels. Our results indicate that Ca2+ ions do not have a direct activating effect on if.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cyclic AMP / metabolism
  • In Vitro Techniques
  • Intracellular Fluid / metabolism
  • Ion Channels / metabolism
  • Membrane Potentials
  • Rabbits
  • Sinoatrial Node / cytology
  • Sinoatrial Node / metabolism*


  • Ion Channels
  • Cyclic AMP
  • Calcium