Ion microscopy evidence that la3+ releases calcium from the golgi
complex in llc-pk1 cells.
Zha, Xiaohui, and George H. Morrison.
Department of Chemistry, Baker Laboratory, Cornell University,
Ithaca, New York 14853
APStracts 2:0170C, 1995.
The effect of La3+ on LLC-PK1 cells was investigated by ion
microscopy, a mass spectrometry based technique with a spatial
resolution of 0.5 [mu]m. Cells were incubated with LaCl3 for 10 min.
(1 mM) or 30 min (0.1 mM), and intracellular calcium distributions
were measured with a Cameca IMS-3f ion microscope in cryogenically
prepared cells. Compared to control cells, La3+ reduced total calcium
in the Golgi complex by more than 100 [mu]M in both treatments, while
other cellular regions, such as the nucleus and cytoplasm, remained
largely unchanged. These two treatments were repeated on cells that
were pre-incubated with 1 mM ouabain. The presence of ouabain in the
medium increased the loss of calcium from the Golgi by about 4-fold
as compared to the treatments without ouabain. The La3+ effect,
therefore, was amplified by ouabain induced Na+ loading, indicating a
possible involvement of a Na+/La3+ exchanger. Lanthanum was detected
within cells, and its influx was facilitated by Na+ loading. These
results suggest that La3+ may affect cellular calcium homeostasis by
actions other than as a simple calcium antagonist.
Received 10 August 1994; accepted in final form 5 April 1995.
APS Manuscript Number C489-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.