Journal article

Publication year: 2001

Pages: 461-468

Journal: Experimental Physiology

Volume number: 86

Issue number: 4

ISSN: 0958-0670

Open access status: Bronze

DOI Link: https://doi.org/10.1113/eph8602243

Publisher: Wiley

Abstract: 
The properties of capacitative Ca2+ influx were studied using the whole-cell patch-clamp technique in crypts isolated from rat distal colon. Store-operated cation influx was evoked by increasing the intracellular buffering capacity for Ca2+ in the pipette solution; contamination by Cl- currents was reduced by the use of NMDG gluconate as the main electrolyte in the pipette solution. The permeability of the non-selective cation conductance stimulated by store depletion had the following sequence for monovalent cations: Cs+ > Na+ greater than or equal to Li+. The store-operated conductance is permeable to Na+ and Ca2+, but in contrast to Na, Ca2+ also exerts a (feedback) inhibition on its own influx. Other divalent cations action with the sequence: Ca2+ greater than or equal to Mg2+ greater than or equal to Ba2+ greater than or equal to Sr-2. Fura-2 experiments revealed that replacement of extracellular Na+ by NMDG(+) induced an increase in the intracellular Ca2+ concentration, which was suppressed by the Na+-Ca2+ exchange inhibitor, dichlorobenzamil, indicating the presence of a Na+-Ca2+ exchanger within the colonic crypt cells. In Ussing chamber experiments dichlorobenzamil induced an increase in short-circuit current (I-sc) in the majority of tissues tested indicating that this exchanger acts as a Ca2+-extruding transporter under physiological conditions. When Ca2+-dependent anion secretion was stimulated by the acetylcholine analogue carbachol, dichlorobenzamil no longer evoked an increase in I-sc, indicating that after stimulation of the store-operated cation conductance the Na+-Ca2+ exchanger is turned off. Therefore, it is concluded that the influx of Na+ across the nonselective store-operated cation conductance serves to reduce the driving force for Ca2+ extrusion via the Na+-Ca2+ exchanger and thereby maintains the increase in the intracellular Ca2+ concentration during induction of secretion.

Harvard Citation style: Seip, G., Schultheiss, G., Kocks, S. and Diener, M. (2001) Interaction Between Store-Operated Non-Selective Cation Channels and the Na+-Ca2+ Exchanger During Secretion in the Rat Colon, Experimental Physiology, 86(4), pp. 461-468. https://doi.org/10.1113/eph8602243

APA Citation style: Seip, G., Schultheiss, G., Kocks, S., & Diener, M. (2001). Interaction Between Store-Operated Non-Selective Cation Channels and the Na+-Ca2+ Exchanger During Secretion in the Rat Colon. Experimental Physiology. 86(4), 461-468. https://doi.org/10.1113/eph8602243