AJP - Cell Physiology, Vol 256, Issue 5 C1022-C1032, Copyright © 1989 by American Physiological Society
Basolateral impalement of intestinal villus cells: electrophysiology of Cl- transport
J. F. White and D. Ellingsen
Department of Physiology, Emory University, Atlanta, Georgia 30322.
A method of dissecting the serosal muscle layers is described that
transforms the villus of isolated Amphiuma small intestine into a flat
sheet one cell layer thick, allowing rapid equilibration of the serosal
medium with the basolateral membrane of the villus tip cells and direct
access of the basal membrane to microelectrodes. The "villus sheet"
preparation was used to examine the luminal and basolateral mechanisms of
Cl- transport. The serosal membrane potential (Vs), measured with
conventional microelectrodes, averaged -79.7 mV in tissues bathed in Cl-
-free medium; the mucosal membrane potential (Vm) averaged -80.9 mV.
Fractional resistance measured directly was 0.82 and 0.14 for the mucosal
and serosal membranes, respectively. Elevation of bath [K] reduced Vm and
Vs by 30.3 and 44.5 mV, respectively. Cl- (20 mM) added to the luminal
medium reduced Vm by 23.9 mV and stimulated Cl- transport; luminal addition
of furosemide then increased Vm by 5.6 mV and reduced Cl- transport.
Addition of Cl- (20 mM) to the Cl- -free serosal fluid increased Vs 2.0 +/-
1.9 mV. On reducing the serosal [Cl] 10-fold Vs decreased 2.0 +/- 2.2 mV.
These and other results indicate that basolateral Cl- exit is not over a
conductive pathway. The villus sheet affords new opportunities for studying
enterocyte function in the intact mucosa.
