chapter  1
16 Pages

Measuring Endogenous Electric Fields

We are electric beings. Every one of our senses utilizes ionic currents and electric šelds at the heart of its transduction mechanism. You are able to read these words because a steady “dark current” is ’owing through the rods in your retina, and this current is being modulated by light absorbed by rhodopsin (Figure 1.1). Light-activated rhodopsin triggers an amplifying signal transduction cascade that leads to the reduction in the cGMP gating of the Na+ channel, and this results in a reduction in the dark current running through that rod. This change in current modišes the rod’s membrane potential and in’uences signaling to other cells in the visual cortex that eventually forms an image in your brain. You are able to hear because compressions of air impinging on your eardrum move hairs or cilia on the cells of your inner ear. These cilia exhibit a “gating spring” mechanism that opens ion channels at their tips when they vibrate to transduce the vibration into membrane potential changes in the hair cell. It is these electrical signals that the brain perceives as noise. Similarly, the senses of

Introduction ........................................................................................................... 1 The Injury Potential/Endogenous Wound Electric Field ...................................... 3 Altering the Injury Potential Can Cause Developmental Defects and Alter the Rate of Wound Healing ................................................................................... 5 Meas uring Bioelectric Fields ................................................................................ 5

Invasive Approaches ......................................................................................... 5 Noninvasive Approaches .................................................................................. 6 How Does the Dermacorder Work? ................................................................. 6 What Have We Learned from This Technique So Far? .................................... 8 Electric Fields Near Mammalian Skin Wounds ............................................... 8 Electric Fields Near Skin Tumors .................................................................... 9 Electric Field Near Bacterial Infections ......................................................... 11

Summary ............................................................................................................. 11 References ........................................................................................................... 13

touch, taste, and smell all have receptor systems that generate electrical signals sent to the brain.