Pflügers Archiv

, Volume 388, Issue 3, pp 217–220 | Cite as

Ionophore A23187 induced reductions in toad urinary bladder epithelial cell oxidative phosphorylation and viability

Implications for A23187 related declines in epithelial active transport
  • H. David Humes
  • Joel M. Weinberg
Transport Processes, Metabolism and Endocrinology; Kidney, Gastrointestinal Tract, and Exocrine Glands

Abstract

The divalent cation ionophore A23187 increased oxygen consumption by isolated epithelial cells from toad urinary bladder, an increase similar to that seen with 2,4-dinitrophenol, a classic uncoupler of mitochondrial oxidative phosphorylation. This respiratory stimulation was not seen in calcium-free incubation media. That this A23187 induced rise in cell oxygen consumption was due to a primary uncoupling action on mitochondrial oxidative phosphorylation rather than secondary to stimulation of cellular transport processes and mediated via increased cellular ADP levels was suggested by the ability of A23187 to release the inhibition of cellular respiration by oligomycin, an inhibitor of the mitochondrial proton ATPase which blocks the stimulation of mitochondrial respiration by ADP. Since active transepithelial ion transport and cellular energy production are closely linked processes, the uncoupling action of A23187 in the presence of extracellular calcium is sufficient to account for an acute decline in active ion transport across epithelia without invoking other calcium-mediated processes. Furthermore, isolated epithelial cells exposed to A23187 for 90 min had greater than 50% loss of viability, as measured by failure of Trypan blue exclusion. The subacute A23187 induced declines in transepithelial transport, therefore, may be secondary to its non-specific effects on cell viability.

Key words

Calcium ionophore A23187 Epithelial transport Toad urinary bladder Oxidative phosphorylation Oxygen consumption Cell viability 

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Copyright information

© Springer-Verlag 1980

Authors and Affiliations

  • H. David Humes
    • 1
  • Joel M. Weinberg
    • 1
  1. 1.Department of Internal MedicineUniversity of MichiganAnn ArborUSA

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