The influence of free fatty acids on functional properties of isolated skeletal muscles. Octanoate action on membrane resistance.
1. Na-octanoate (in Ringer's solution) affects the membrane resistance of isolated frog skeletal muscle fibres in a biphasic way. Initially there is an increase followed by a more slowly developing decrease. The effect depends on both the concentration of the fatty acid (1-20 mM) and the time of exposure (2-20 min). 2. In muscles exposed either to isotonic K2SO4 or to Ringer's solution with Cl- substituted by methylsulphage, the octanoate-induced resistance drop is the same as in normal Ringer's solution whereas an initial increase is not observed. 3. In Na-free (Tris-) Ringer's solution, only an increase in membrane resistance is caused by octanoate. 4. The results suggest that Na-octanoate decreases the conductance of the resting muscle cell membrane for anions (Cl-1) whereas the permeability for cations (Na+, K+) is increased.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001001:Anura; D002210:Caprylates / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009132:Muscles / Q000187:drug effects* / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D011893:Rana esculenta; D012964:Sodium / Q000378:metabolism
D002210:Caprylates; D002712:Chlorides; D012964:Sodium; D011188:Potassium