AJP - Cell Physiology, Vol 262, Issue 1 C221-C228, Copyright © 1992 by American Physiological Society
Changes in pHi associated with activation of ion secretion in avian nasal salt gland cells
T. J. Shuttleworth and C. M. Wood
Department of Physiology, University of Rochester School of Medicine, New York 14642.
The fluorescent pH-sensitive dye 2',7'-bis(2-carboxyethyl)-5(6)-
carboxyfluorescein (BCECF) was used to determine changes in intracellular
pH (pHi) associated with activation of secretion in isolated cells from the
salt-secreting avian nasal gland. A correction procedure overcoming
artifacts due to BCECF leakage is described. Resting pHi averaged 7.15 +/-
0.03 and was unaffected by the nominal removal of medium HCO3- or by the
addition of the anion-exchange inhibitor
4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) but was
significantly reduced by amiloride (7.07 +/- 0.02). Muscarinic activation
of secretion resulted in a rapid intracellular acidification that was
compensated by mechanisms which raised pHi to restore approximately resting
levels within 5 min. The principal mechanism involved was
amiloride-sensitive and independent of any sustained intracellular Ca2+
concentration change. Recovery of pHi was also aided by HCO3(-)-dependent
and DIDS-sensitive mechanisms not seen in the resting cell. The direction
of the latter was pHi-dependent, with DIDS further decreasing pHi in
acidified cells and increasing pHi in alkalinized cells. This suggests that
the DIDS-sensitive pathways are activated under conditions where pHi has
been shifted away from resting levels in either direction and act primarily
to restore resting pHi.
