AJP - Gastrointestinal and Liver Physiology, Vol 248, Issue 5 574-G579, Copyright © 1985 by American Physiological Society
Microelectrode studies of Necturus antral mucosa. II. Equivalent circuit analysis
S. W. Ashley, D. I. Soybel, L. De and L. Y. Cheung
Intracellular microelectrode techniques were employed to determine the
equivalent circuit parameters in Necturus antral mucosa. Stable
intracellular impalements were obtained using 15- to 50-M omega
microelectrodes. Measured transepithelial and cellular potentials and
voltage deflections produced by transepithelial current pulses were used to
calculate the electrical resistances of the cell membranes and the
equivalent electromotive forces (EMF) at both cell borders. The measured
potentials were -4.1 +/- 0.8 mV for the entire epithelia, -41.8 +/- 5.1 mV
for the apical membrane, and -45.9 +/- 5.0 mV for the basolateral membrane.
Values for the resistances were 7,300 +/- 1,900 omega X cm2 for the apical,
3,990 +/- 1,170 omega X cm2 for the basolateral, and 710 +/- 40 omega X cm2
for the shunt. Assuming that the shunt EMF is zero with control Ringer
solution on both sides of the tissue, the effect of this relatively
low-resistance shunt on electrical parameters can be determined. The cell
membrane EMFs are both oriented with the interior negative and are -1.2 +/-
9.7 mV (apical) and -69.7 +/- 11.3 mV (basolateral). The difference between
these values and the measured potentials is the result of a flow of current
through the shunt from serosa to mucosa, hyperpolarizing the apical and
depolarizing the basolateral membranes.
