Muscarinic stimulation of gallbladder epithelium I. Electrophysiology and signaling mechanisms

G. A. Altenberg, M. Subramanyam, J. S. Bergmann, K. M. Johnson, L. Reuss

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

To understand the effects of acetylcholine (ACh) on fluid-absorbing epithelia, we carried out experiments on Necturus gallbladder epithelium. Binding studies with 1-quinuclidinyl[phenyl-4(N)-3H]benzilate (QNB) demonstrated that Necturus gallbladder epithelial cells express high-affinity muscarinic receptors. The effects of ACh and carbachol were exerted from the basolateral surface and consisted of a transient hyperpolarization of both cell membranes and a concomitant decrease in the apparent fractional resistance of the apical membrane. Atropine blocked both effects. ACh also elicited transient elevations of inositol 1,4,5-trisphosphate and intracellular free calcium ([Ca2+](i)) levels, the latter by both release from intracellular stores and basolateral influx. The phospholipase C antagonist U-73122 inhibited the effects of ACh, whereas inhibition of prostaglandin and guanosine 3',5'-cyclic monophosphate synthesis with indomethacin or methylene blue, respectively, had no effect. In conclusion, Necturus gallbladder epithelium expresses muscarinic receptors in the basolateral membrane. Receptor activation stimulates phospholipase C and elevates cellular levels of inositol 1,4,5-trisphosphate and [Ca2+](i). The elevation in [Ca2+](i) activates K+ channels but apparently not Cl- channels.

Original languageEnglish (US)
Pages (from-to)C1604-C1612
JournalAmerican Journal of Physiology - Cell Physiology
Volume265
Issue number6 34-6
StatePublished - Dec 1 1993

    Fingerprint

Keywords

  • acetylcholine
  • inositol 1,4,5-trisphosphate
  • intracellular calcium
  • maxi potassium channel
  • phospholipase C
  • proximal tubule
  • small intestine

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

Cite this

Altenberg, G. A., Subramanyam, M., Bergmann, J. S., Johnson, K. M., & Reuss, L. (1993). Muscarinic stimulation of gallbladder epithelium I. Electrophysiology and signaling mechanisms. American Journal of Physiology - Cell Physiology, 265(6 34-6), C1604-C1612.