Abstract
Alternating currents can increase or decrease the ATP-splitting activity of the membrane enzyme Na,K-ATPase. Either change depends on the AC frequency, and the greatest effect appears to be in the ELF range at about 100 Hz. The threshold for enzyme inhibition by AC was determined, and it is estimated to be an internal electric field circa 5 μV/cm. The corresponding current-density threshold approximates 8 nA/cm2. 1992 Wiley-Liss, Inc.