Ca2+-dependent K+ Channels in Bovine Adrenal Chromaffin Cells are Modulated by Lipoxygenase Metabolites of Arachidonic Acid

Ca2+-dependent K+ Channels in Bovine Adrenal Chromaffin Cells are Modulated by Lipoxygenase... Fatty acids play an important role in a variety of physiological processes including ion channel modulation and catecholamine release. Using patch-clamp techniques we show that arachidonic acid (AA) is converted to lipoxygenase metabolites (LOMs) to potentiate activity of the Ca2+ and voltage-dependent, large-conductance K+ channel (BK) in bovine adrenal medullary chromaffin cells (BAMCCs). AA and LOM potentiation of BK current and recovery from potentiation were unaffected by the nonhydrolyzable ATP analogue AMP-PNP, or by exclusion of nucleotides in excised patch recordings. Also, AA and LOM potentiation of BK channel activity in outside-out patches exposed to strong Ca2+ buffering ruled out cytoplasmic messengers or changes in intracellular Ca2+ levels as causative factors. Lipoxygenase inhibitor attenuated AA, but not LOM potentiation of BK activity in outside-out patches, indicating that lipoxygenase processing of AA is possible in excised membrane patches, possibly via a membrane associated lipoxygenase. AA and LOM release have been implicated in the mechanics of catecholamine secretion from BAMCCs. By limiting action potential duration and thus voltage-gated Ca2+ influx, fatty acid potentiation of BK current may serve an inhibitory feedback function in regulating secretion from BAMCCs. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Ca2+-dependent K+ Channels in Bovine Adrenal Chromaffin Cells are Modulated by Lipoxygenase Metabolites of Arachidonic Acid

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Publisher
Springer Journals
Copyright
Copyright © Inc. by 1997 Springer-Verlag New York
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s002329900244
Publisher site
See Article on Publisher Site

Abstract

Fatty acids play an important role in a variety of physiological processes including ion channel modulation and catecholamine release. Using patch-clamp techniques we show that arachidonic acid (AA) is converted to lipoxygenase metabolites (LOMs) to potentiate activity of the Ca2+ and voltage-dependent, large-conductance K+ channel (BK) in bovine adrenal medullary chromaffin cells (BAMCCs). AA and LOM potentiation of BK current and recovery from potentiation were unaffected by the nonhydrolyzable ATP analogue AMP-PNP, or by exclusion of nucleotides in excised patch recordings. Also, AA and LOM potentiation of BK channel activity in outside-out patches exposed to strong Ca2+ buffering ruled out cytoplasmic messengers or changes in intracellular Ca2+ levels as causative factors. Lipoxygenase inhibitor attenuated AA, but not LOM potentiation of BK activity in outside-out patches, indicating that lipoxygenase processing of AA is possible in excised membrane patches, possibly via a membrane associated lipoxygenase. AA and LOM release have been implicated in the mechanics of catecholamine secretion from BAMCCs. By limiting action potential duration and thus voltage-gated Ca2+ influx, fatty acid potentiation of BK current may serve an inhibitory feedback function in regulating secretion from BAMCCs.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jul 1, 1997

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