EFFECT OF CURRENT, IONIC-STRENGTH AND TEMPERATURE ON THE ELECTRICAL-PROPERTIES OF SKIN

The complex electrical impedance of hairless mouse skin was measured a s a fun on of frequency, and resistance and capacitance were determine d. Increasing the ionic strength of the bathing medium, and increasing the magnitude of current, decreased resistance, whereas capacitance w as, in general, unchanged. These changes occurred rapidly. The decreas e in resistance with increasing the ionic strength of the bathing medi um was consistent with elevated ion levels within the ion-conducting p athways of the membrane. The decrease in resistance by increasing the magnitude of current seems to be related to alteration of the current- conducting pathway. With increasing temperature, resistance also decre ased while capacitance increased. The activation energy for ion conduc tion through the skin was estimated to be 3.4 kcal/mol at physiologica lly relevant temperatures. The most marked changes occurred at the pha se transition temperature (60-degrees-C) of the stratum corneum (SC) l ipids; resistance fell dramatically and capacitance steadily increased - ultimately, the impedance became independent of frequency, suggesti ng that the capacitive properties of the barrier had been lost. Overal l, the results provide mechanistic insight into ion conduction through the skin and into the role of SC lipids in skin capacitance.