Journal article

Publication year: 2002

Pages: 390-397

Journal: Pflügers Archiv European Journal of Physiology

Volume number: 445

Issue number: 3

ISSN: 0031-6768

DOI Link: https://doi.org/10.1007/s00424-002-0947-1

Publisher: Springer

Abstract: 
The properties of the Na+-Ca2+ exchanger in isolated crypts from rat colon were studied using the Fura-2 imaging technique. The transport mode of the exchanger was reversed by replacing extracellular Na+ by the impermeable cation, N-methyl-D-glucamine (NMDG(+)), so that the transporter mediated a Ca2+ influx into the cells. Depletion of intracellular Ca2+ stores by inhibitors of sarcoplasmatic endoplasmatic calcium ATPases (SERCA), i.e., cyclopiazonic acid (10(-5) mol l(-1)) or thapsigargin (10(-6) mol l(-1)), reduced the increase in [Ca2+](i) evoked by superfusion with NMDG(+) suggesting a cross-talk between the exchanger and the Ca2+ stores. However, measurement of Ca2+ influx with the Mn2+ quench technique revealed that the activity of the exchanger was independent of the filling state of the stores. Instead, the obvious inhibition of the [Ca2+](i) response by SERCA blockers was due to a reduction of Ca2+-induced Ca2+ release after inhibition of store-refilling. The functional presence of ryanodine receptors was demonstrated by the increase in [Ca2+](i) evoked by ryanodine (10(-7) to 3x10(-4) mol l(-1)) in a concentration-dependent manner. This effect was mimicked by cADP ribose (10(-5) mol l(-1)) in crypts permeabilized with saponin (10 mg l(-1)). Ruthenium red (5x10(-5) mol l(-1)) or high concentrations of ryanodine (3x10(-4) mol l(-1)) inhibited this response. In Ussing chamber experiments ruthenium red (5x10(-4) mol l(-1)) or a high concentration of ryanodine (10(-3) mol l(-1)) inhibited the increase in short-circuit current evoked by the cholinergic agonist, carbachol (5x 10(-5) mol l(-1)). Consequently, Ca2+-induced Ca2+ release may act as kind of amplifier during Ca2+-dependent Cl- secretion in order to maintain a long-lasting increase in the intracellular Ca2+ concentration.

Harvard Citation style: Kocks, S., Schultheiss, G. and Diener, M. (2002) Ryanodine receptors and the mediation of Ca2+-dependent anion secretion across rat colon, Pflügers Archiv European Journal of Physiology, 445(3), pp. 390-397. https://doi.org/10.1007/s00424-002-0947-1

APA Citation style: Kocks, S., Schultheiss, G., & Diener, M. (2002). Ryanodine receptors and the mediation of Ca2+-dependent anion secretion across rat colon. Pflügers Archiv European Journal of Physiology. 445(3), 390-397. https://doi.org/10.1007/s00424-002-0947-1