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MEMBRANE PHOTOMODIFICATION OF CARDIAC MYOCYTES: POTASSIUM AND LEAKAGE CURRENTS
Author(s) -
VALENZENO DENNIS PAUL,
TARR MERRILL
Publication year - 1991
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1991.tb03923.x
Subject(s) - myocyte , potassium , leakage (economics) , biophysics , chemistry , membrane potential , potassium channel , membrane , microbiology and biotechnology , biochemistry , biology , organic chemistry , economics , macroeconomics
— Cardiac myocytes were isolated from the atria of frogs ( Rana pipiens ) and whole cell potassium (I k ) and “leakage” (I lcak ) currents were monitored using the patch clamp technnique. Cells were photosensitized by exposure to Rose Bengal (0.125–0.5 μ M ). Illumination produced an exponential decrease in I k , and an increase in I leak . Current modifications varied with light intensity and sensitizer concentration. I k stabilized when illumination ceased, while I lcak continued to increase at a slower rate after illumination ended. The exponential nature of I k modification suggests that potassium channels are photomodified with single hit kinetics. The stabilization of I k following illumination suggests (1) that the photomodification of the potassium channel does not involve long lasting (minutes) radical chain reactions and (2) that this photomodification is not repaired in the course of a few minutes.