Acetylcholine increases intracellular Ca2+ in taste cells via activation of muscarinic receptors

J Neurophysiol. 2002 Jun;87(6):2643-9. doi: 10.1152/jn.2002.87.6.2643.


Previous studies suggest that acetylcholine (ACh) is a transmitter released from taste cells as well as a transmitter in cholinergic efferent neurons innervating taste buds. However, the physiological effects on taste cells have not been established. I examined effects of ACh on taste-receptor cells by monitoring [Ca2+]i. ACh increased [Ca2+]i in both rat and mudpuppy taste cells. Atropine blocked the ACh response, but D-tubocurarine did not. U73122, a phospholipase C inhibitor, and thapsigargin, a Ca2+-ATPase inhibitor that depletes intracellular Ca2+ stores, blocked the ACh response. These results suggest that ACh binds to M1/M3/M5-like subtypes of muscarinic ACh receptors, causing an increase in inositol 1,4,5-trisphosphate and subsequent release of Ca2+ from the intracellular stores. A long incubation with ACh induced a transient response followed by a sustained phase of [Ca2+]i increase. In Ca2+-free solution, the sustained phases disappeared, suggesting that Ca2+ influx is involved in the sustained phase. Depletion of Ca2+ stores by thapsigargin alone induced Ca2+ influx. These findings suggest that Ca2+ store-operated channels may be present in taste cells and that they may participate in the sustained phase of [Ca2+]i increase. Immunocytochemical experiments indicated that the M1 subtype of muscarinic receptors is present in both rat and mudpuppy taste cells.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetylcholine / pharmacology*
  • Animals
  • Antibodies
  • Calcium / metabolism*
  • Necturus
  • Rats
  • Rats, Sprague-Dawley
  • Receptor, Muscarinic M1
  • Receptor, Muscarinic M2
  • Receptor, Muscarinic M5
  • Receptors, Muscarinic / analysis
  • Receptors, Muscarinic / immunology
  • Receptors, Muscarinic / metabolism*
  • Taste Buds / chemistry
  • Taste Buds / drug effects*
  • Taste Buds / metabolism*


  • Antibodies
  • Receptor, Muscarinic M1
  • Receptor, Muscarinic M2
  • Receptor, Muscarinic M5
  • Receptors, Muscarinic
  • Acetylcholine
  • Calcium