Evidence for a Na+-Ca2+ exchanger in rat pancreatic ducts.
Only recently has it been recognized that intracellular Ca2+ is an important cellular mediator in pancreatic ducts. The aim of the present study was to characterize the Ca2+ efflux pathway in ducts freshly prepared from rat pancreas. Lowering of extracellular Na+ concentration resulted in a significant increase in intracellular Ca2+. This effect was fast, reversible, dependent on the extracellular Na+ concentration and did not correlate with intracellular pH changes. It was abolished in Ca2+-free solutions, indicating that the outwardly directed Na+ gradient was directly coupled to a flufenamate insensitive Ca2+ influx. Removal and reintroduction of extracellular Na+ induced transient hyperpolarization and depolarization of Vm, respectively. Taken together, our data indicate that pancreatic ducts possess an electrogenic Na+-Ca2+ exchanger, which under control conditions is responsible for transporting Ca2+ out of resting duct cells.
Hug
M
M
Physiologisches Institut, Albert-Ludwigs-Universität, Freiburg, Germany.
Pahl
C
C
Novak
I
I
D000085:Acetates / Q000494:pharmacology; D000818:Animals; D015764:Bepridil / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D005260:Female; D005439:Flufenamic Acid / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D010183:Pancreatic Ducts / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology; D019831:Sodium-Calcium Exchanger
D000085:Acetates; D002121:Calcium Channel Blockers; D002352:Carrier Proteins; D006146:Guanidines; D019831:Sodium-Calcium Exchanger; D005439:Flufenamic Acid; D015764:Bepridil; D012964:Sodium; D002118:Calcium