ISSN:
1432-1424
Keywords:
Corneal endothelium
;
K+ channel
;
Temperature sensitivity
;
Resting voltage
;
Patch clamp
;
Perforated patch
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Previous studies have shown that the resting potential (E m) of the corneal endothelium hyperpolarizes following an increase in temperature above 24°C. Whole-cell studies using the perforated-patch technique were used to compare currents and E mvalues from isolated corneal endothelial cells at 24 and 32°C. These studies revealed a small, outwardly rectifying, slowly activating, weakly voltage-dependent current with a reversal potential showing K+ selectivity (E rev = −80 mV). This current had features similar to the whole-cell current seen following addition of HCO3 − to these cells. E mmeasurements found an average 24 mV hyperpolarization following temperature elevation in NaCl Ringer. Single channel studies found the only change in channel activity following an elevation in temperature to be an increase in the open probability (P o) of a K+ channel previously reported in this cell type to be activated by external anions. P o(−30 mV) at 24 and 32°C equaled 0.003 and 0.06, respectively. Increases in P owere found at all voltages examined. This increased P ocan account for the magnitude of the hyperpolarization seen in these cells following temperature elevation. Addition of HCO3 − along with elevated temperature produced a synergistic effect on the increase in P oalong with an increased hyperpolarization of the cell, pointing to separate mechanisms of activation from these two stimuli.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00234652
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