Osmotically induced electrical signals from actin filaments.
Actin filaments, F-actin, a major component of the cortical cytoskeleton, play an important role in a variety of cell functions. In this report we have assessed the role of osmotic stress on the electrochemical properties of F-actin. The spontaneous Donnan potential of a polymerized actin solution (5 mg/ml) was -3.93 +/- 1.84 mV, which was linearly reduced by osmotic stress on the order of 1-20 mOsm (0.28 +/- 0.06 mV/mM). Calculated surface charge density was reduced and eventually reversed by increasing the osmotic stress as expected for a phase transition behavior. The electro-osmotic behavior of F-actin disappeared at pH 5.5 and was dependent on its filamentous nature. Furthermore, osmotically stressed F-actin displayed a nonlinear electric response upon application of electric fields on the order of 500-2,000 V/cm. These data indicate that F-actin in solution may display nonideal electro-osmotic properties consistent with ionic "cable" behavior which may be of biological significance in the processing and conduction of electrical signals within the cellular compartment.
Cantiello
H F
HF
Renal Unit, Massachusetts General Hospital, Boston.
Patenaude
C
C
Zaner
K
K
D000199:Actins / Q000737:chemistry*; D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D004560:Electricity; D004563:Electrochemistry; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009997:Osmotic Pressure; D011817:Rabbits; D012996:Solutions
D000199:Actins; D012996:Solutions