Structural requirements for charged lipid molecules to directly increase or suppress K+ channel activity in smooth muscle cells. Effects of fatty acids, lysophosphatidate, acyl coenzyme A and sphingosine
Graduate School of Biomedical Sciences; Department of Physiology
Medical Subject Headings
Acyl Coenzyme A; Amines; Animals; Bufo marinus; Cell Separation; Electrochemistry; Electrophysiology; Fatty Acids; Lipid Bilayers; Lipids; Lysophospholipids; Muscle, Smooth; Potassium Channels; Sphingosine
Life Sciences | Medicine and Health Sciences
We determined the structural features necessary for fatty acids to exert their action on K+ channels of gastric smooth muscle cells. Examination of the effects of a variety of synthetic and naturally occurring lipid compounds on K+ channel activity in cell-attached and excised membrane patches revealed that negatively charged analogs of medium to long chain fatty acids (but not short chain analogs) as well as certain other negatively charged lipids activate the channels. In contrast, positively charged, medium to long chain analogs suppress activity, and neutral analogs are without effect. The key requirements for effective compounds seem to be a sufficiently hydrophobic domain and the presence of a charged group. Furthermore, those negatively charged compounds unable to "flip" across the bilayer are effective only when applied at the cytosolic surface of the membrane, suggesting that the site of fatty acid action is also located there. Finally, because some of the effective compounds, for example, the fatty acids themselves, lysophosphatidate, acyl Coenzyme A, and sphingosine, are naturally occurring substances and can be liberated by agonist-activated or metabolic enzymes, they may act as second messengers targeting ion channels.
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Citation: J Gen Physiol. 1994 Mar;103(3):471-86.
The Journal of general physiology
Petrou, Steven; Ordway, Richard W.; Hamilton, James A.; Walsh, John V.; and Singer, Joshua J., "Structural requirements for charged lipid molecules to directly increase or suppress K+ channel activity in smooth muscle cells. Effects of fatty acids, lysophosphatidate, acyl coenzyme A and sphingosine" (1994). GSBS Student Publications. 983.