Ion transport in an immortalized rat submandibular cell line SMG-C6.
The immortalized rat submandibular epithelial cell line, SMG-C6, cultured on porous tissue culture supports, forms polarized, tight-junction epithelia facilitating bioelectric characterization in Ussing chambers. The SMG-C6 epithelia generated transepithelial resistances of 956+/-84Omega.cm2 and potential differences (PD) of -16.9 +/- 1.5mV (apical surface negative) with a basal short-circuit current (Isc) of 23.9 +/- 1.7 microA/cm2 (n = 69). P2 nucleotide receptor agonists, ATP or UTP, applied apically or basolaterally induced a transient increase in Isc, followed by a sustained decreased below baseline value. The peak DeltaIsc increase was partly sensitive to Cl- and K+ channel inhibitors, DPC, glibenclamide, and tetraethylammonium (TEA) and was completely abolished following Ca2+ chelation with BAPTA or bilateral substitution of gluconate for Cl-. The major component of basal Isc was sensitive to apical Na+ replacement or amiloride (half-maximal inhibitory concentration 392 nM). Following pretreatment with amiloride, ATP induced a significantly greater Isc; however, the poststimulatory decline was abolished, suggesting an ATP-induced inhibition of amiloride-sensitive Na+ transport. Consistent with the ion transport properties found in Ussing chambers, SMG-C6 cells express the rat epithelial Na+ channel alpha-subunit (alpha-rENaC). Thus, cultured SMG-C6 cells produce tight polarized epithelia on permeable support with stimulated Cl- secretory conductance and an inward Isc accounted for by amiloride-sensitive Na+ absorption.
Castro
R
R
Department of Pediatrics, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78284-7812, USA. castror@uthscsa.edu
Barlow-Walden
L
L
Woodson
T
T
Kerecman
J D
JD
Zhang
G H
GH
Martinez
J R
JR
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002461:Cell Line, Transformed; D002614:Chelating Agents / Q000494:pharmacology; D002712:Chlorides / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D004553:Electric Conductivity; D017097:Electric Impedance; D004847:Epithelial Cells / Q000378:metabolism; D005942:Gluconates / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects; D007633:Keratins / Q000032:analysis; D008564:Membrane Potentials; D026902:Potassium Channel Blockers; D051381:Rats; D012964:Sodium / Q000378:metabolism; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology; D013363:Submandibular Gland / Q000378:metabolism*; D019108:Tight Junctions / Q000502:physiology
D002614:Chelating Agents; D002712:Chlorides; D005942:Gluconates; D026902:Potassium Channel Blockers; D015222:Sodium Channels; D004533:Egtazic Acid; D007633:Keratins; D000584:Amiloride; D000255:Adenosine Triphosphate; D012964:Sodium; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; C030691:gluconic acid; D002118:Calcium