Caprylic acid, a medium chain saturated fatty acid, inhibits the sodium inward current in neuroglioma (NG108-15) cells.
The effects of caprylic acid (CA) on ionic currents were investigated, using the whole-cell patch-clamp technique, in differentiated neuroglioma cells. External application of CA reduced the peak amplitude of the inward Na+ current, while outward currents were not affected. CA (1 and 5 mM) reversibly attenuated the peak of the inward Na+ current by 21% (n = 26) and 46% (n = 31), respectively. The inactivation curve in the presence of CA was shifted by 8 mV toward hyperpolarized potentials, with half-inactivation voltage being -47.9 and -55.9 before and after external application of CA (5 mM), respectively. This shift was readily reversed after 5 min wash. The slope remained unchanged (-8.4 and -8.8 mV, respectively, n = 4). The activation process was unaffected (CA 5 mM, n = 8). Under current-clamp conditions, CA 5 mM (but not 1 mM) reversibly reduced the amplitude, and the slope of the rising phase of the action potential. These results agree with the fact that free fatty acids can modulate the activity of ion channels by mechanisms which do not involve enzymatic or membrane disruptive pathways.
Lamas
J A
JA
Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, Spain.
Martinez
L
L
Canedo
A
A
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D002210:Caprylates / Q000494:pharmacology*; D002460:Cell Line; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005910:Glioma / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015222:Sodium Channels / Q000187:drug effects*
D000959:Antihypertensive Agents; D002210:Caprylates; D005230:Fatty Acids, Nonesterified; D015222:Sodium Channels; C031492:octanoic acid