Inhibitory effect of caffeine on pacemaker activity in the oviduct is mediated by cAMP-regulated conductances

Rose Ellen Dickson, S. J. Hwang, F. C. Britton, K. M. Sanders, S. M. Ward

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


BACKGROUND AND PURPOSE Spontaneous electrical activity, termed slow waves, drives rhythmic, propulsive contractions in the smooth muscle of the oviduct (myosalpinx). Myosalpinx contractions cause egg transport through the oviduct. Agents that disrupt slow wave pacemaker activity will therefore disrupt myosalpinx contractions and egg transport. Caffeine is commonly used as a ryanodine receptor agonist and has been previously associated with delayed conception. Here we assessed the effects of caffeine on pacemaker activity in the murine myosalpinx. EXPERIMENTAL APPROACH The effects of caffeine on electrical pacemaker activity were studied using intracellular microelectrode and isometric force measurements on intact oviduct muscle preparations. Responses to caffeine were compared with responses caused by 3-isobutyl-1-methylxanthine (IBMX) and forskolin. KEY RESULTS Caffeine caused hyperpolarization of membrane potential and inhibited slow wave generation and myosalpinx contractions. The effects of caffeine could be mimicked by the K ATP channel agonist pinacidil and antagonized by the K ATP channel antagonist glibenclamide. Caffeine is known to inhibit cyclic nucleotide phosphodiesterases (PDEs), leading to an increase in cytosolic cAMP and stimulation of downstream cAMP-dependent mechanisms. The effects of caffeine were mimicked by the PDE inhibitor, IBMX, and the adenylyl cyclase activator forskolin. These effects were also reversed by glibenclamide. CONCLUSIONS AND IMPLICATIONS These results suggest that caffeine activates K ATP channels in oviduct myosalpinx. Since caffeine abolishes slow waves and associated contractions of the myosalpinx, it would have a negative effect on egg transport through the oviduct and may contribute to the documented delayed conception in women consuming caffeinated beverages.

Original languageEnglish (US)
Pages (from-to)745-754
Number of pages10
JournalBritish Journal of Pharmacology
Issue number4
StatePublished - Jun 2011
Externally publishedYes


  • caffeine
  • cAMP
  • female reproductive tract
  • K
  • myosalpinx
  • oviduct
  • smooth muscle

ASJC Scopus subject areas

  • Pharmacology


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