Regulation of a voltage-dependent, calcium-activated K conductance by cyclic GMP in dissociated flounder enterocytes

S. M. O'Grady, K. E. Cooper, J. L. Rae

Research output: Contribution to journalArticlepeer-review


Enterocytes from the winter flounder (Pseudopleuronectes americanus) were isolated by collagenase digestion and maintained in flounder Ringer's solution. Whole cell currents were studied using the amphotericin-perforated whole-cell patch clamp technique. The mean resting membrane potential and capacitance values or dissociated cells were-45±7 mV and 5±0.4 pF, respectively. Enterocytes held at-20 mV and treated with 1 μmol·l-1 ionomycin exhibited outward currents when cells were stepped through a series of voltages from-60 to +110 mV. The reversal potential of this current in flounder Ringer's solution was-55 mV and the voltage at which half-maximal activation occurred was +20 mV. Voltage-dependent inhibition of outward current was observed at +60 mV and above. When cells were bathed in symmetric K Ringer's solution the reversal potential shifted to zero mV and no inhibition of current was observed at voltages between-60 and 140 mV. When the holding potential of the cell was changed from-20 to-80 mV and stepped from-60 to +110 mV, a second [previously characterized, O'Grady et al. (1991)] K current with delayed-rectifier properties was identified. This observation demonstrated that the delayed rectifier K channel and the Ca2+-activated K channel described in this study exist in the same cell. Extracellular addition of 2 mmol·l-1 Ba2+ to cells bathed in symmetric K Ringer's solution resulted in nearly complete inhibition of outward current. Charybdotoxin produced only minor effects on this current. Addition of 8-Br cGMP to the bathing solution also inhibited outward current and this effect could be partially reversed following washout of 8-Br cGMP from the bathing solution. The results of this study indicated that a Ca2+-activated K conductance in winter flounder enterocytes is potentially inhibited by agents that increase intracellular cGMP. A similar effect of cGMP on a delayed rectifier K channel in flounder enterocytes was previously demonstrated.

Original languageEnglish (US)
Pages (from-to)581-586
Number of pages6
JournalJournal of Comparative Physiology B
Issue number7
StatePublished - Dec 1993


  • Flounder, (Pseudopleuronectes americanus)
  • Intestine
  • Ion transport
  • K secretion
  • Membrane transport


Dive into the research topics of 'Regulation of a voltage-dependent, calcium-activated K conductance by cyclic GMP in dissociated flounder enterocytes'. Together they form a unique fingerprint.

Cite this