Pge2 stimulates mg2+ uptake in mouse distal convoluted tubule
cells.
Dai, Long-Jun, Brian Bapty, Gordon Ritchie, and Gary A. Quamme.
Department of Medicine, University of British Columbia, Vancouver
Hospital and Health Sciences Centre, Koerner Pavilion, Vancouver, BC
Canada
APStracts 5:0142F, 1998.
Prostaglandins have diverse effects on renal electrolyte reabsorption,
inhibiting NaCl absorption in the thick ascending limb and modulating
sodium and calcium transport in cortical collecting cells. It is
unclear what effect, if any, prostaglandins have on tubular magnesium
handling. The effects of PGE2 were studied on immortalized mouse
distal convoluted tubule (MDCT) cells by measuring cellular cAMP
formation with radioimmunoassays and Mg2+ uptake with fluorescence
techniques. Intracellular free Mg2+ concentration ([Mg2+]i) was
measured on single MDCT cells using microfluorescence with mag-fura
-2. To assess Mg2+ uptake, MDCT cells were first Mg2+-depleted to
0.22[angstrom]a0.01 mM by culturing in Mg2+-free media for 16 hr and
then placed in 1.5 mM MgCl2 and the changes in [Mg2+]i was
determined. [Mg2+]i returned to basal levels, 0.53[angstrom]a0.02 mM,
with a mean refill rate, d([Mg2+]i)/dt, of 173[angstrom]a8 nM/s.
Indomethacin, 5 _M diminished basal Mg2+ uptake suggesting that
endogenous prostaglandins may stimulate Mg2+ entry in control cells.
PGE2 stimulated Mg2+ entry in a concentration-dependent manner with
maximal response of 311[angstrom]a12 nM/s, at a concentration of 10-7
M, that represented a 80[angstrom]a3% increase in uptake rate above
control values. This was associated with a 6-fold increase in
intracellular cAMP generation. PGE2-stimulated Mg2+ uptake was
completely inhibited with RpcAMPS, a protein kinase A inhibitor, and
U-73122, a phospholipase C inhibitor, and partially by chelerythrine,
a protein kinase C inhibitor. Accordingly, PGE2 -mediated Mg2+ entry
rates involve multiple intracellular signalling pathways. These
studies demonstrate that PGE2 stimulates Mg2+ uptake in a cell line
of mouse distal convoluted tubules.
Received 31 March 1998; accepted in final form 13 August 1998.
APS Manuscript Number F79-8.
Article publication pending Am. J. Physiol. (Renal Physiology).
ISSN 1080-4757 Copyright 1998 The American Physiological Society.
Published in APStracts on 21 September 1998