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Na+/Ca2+ exchanger in epithelial cells of porcine cortical thick ascending limb

Friday, September 11th, 2009

Dai LJ, Ritchie G, Bapty B, and Quamme GA: Na+/Ca2+ exchanger in epithelial cells of   porcine cortical thick ascending limb. American Journal of Physiology 270:F411-F418, 1996.

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Na+/Ca2+ exchanger in epithelial cells of the porcine cortical thick ascending limb. Am. J. Physiol. 270 (Renal Fluid Electrolyte Physiol. 39): F411-F418,1996.-Intracellular Ca2+ concentration ( [Ca2+]i) plays an important role in the signal transduction processes within cortical thick ascending limb (CTAL) cells. Control of [Ca2+]; was investigated in isolated CTAL cells with microfluorescent techniques. CTAL cells pretreated with ouabain to elevate intracellular Na+ concentration ([Na+]i) had basal [Ca2+]. 10 f 86 IT 2 nM. Removal of extracellular Na (Na,f ) or voltage depolarization with KC1 (in the presence of Na,f) resulted in a rapid and reversible maximal elevation of [Ca2+]i (1,023 t 72 nM, n = ZS), which was dependent on the presence of external Ca 2+ (Caf’). The rise in [Ca2+]i was inhibited with La3+, Mg2+, amiloride, and bepridil. The increments of [Ca2+]i with either removal of Naz or voltage depolarization were dependent on pretreatment with ouabain and increases in [Na+]i. The presence of a Na+/Ca2+ exchanger was confirmed with hybridization techniques, and the isoform was identified by sequencing the alternative splicing site within the intracellular loop. A gene transcript that encodes a portion of the intracellular loop of the renal Na+/Ca2+ exchanger was amplified from cortical tissue and single CTAL cells by reverse transcription-polymerase chain reaction, using primers flanking the alternative splicing site. Southern hybridization and DNA sequencing demonstrated the isoform contained exons B and D, which is characteristic of one isoform (NACA3) of the renal Na+/Ca2+ exchanger. The results provide both functional and molecular evidence for a Na+/Ca2+ exchanger in thick ascending limb cells of the porcine kidney.

Na+/Ca2+ exchanger in
epithelial cells of the porcine cortical thick ascending limb.
Am. J. Physiol. 270 (Renal Fluid Electrolyte Physiol. 39):
F411-F418,1996.-Intracellular Ca2+ concentration ( [Ca2+]i)
plays an important role in the signal transduction processes
within cortical thick ascending limb (CTAL) cells. Control of
[Ca2+]; was investigated in isolated CTAL cells with microfluorescent
techniques. CTAL cells pretreated with ouabain to
elevate intracellular Na+ concentration ([Na+]i) had basal
[Ca2+]. 10 f 86 IT 2 nM. Removal of extracellular Na (Na,f ) or
voltage depolarization with KC1 (in the presence of Na,f)
resulted in a rapid and reversible maximal elevation of
[Ca2+]i (1,023 t 72 nM, n = ZS), which was dependent on the
presence of external Ca 2+ (Caf’). The rise in [Ca2+]i was
inhibited with La3+, Mg2+, amiloride, and bepridil. The
increments of [Ca2+]i with either removal of Naz or voltage
depolarization were dependent on pretreatment with ouabain
and increases in [Na+]i. The presence of a Na+/Ca2+ exchanger
was confirmed with hybridization techniques, and
the isoform was identified by sequencing the alternative
splicing site within the intracellular loop. A gene transcript
that encodes a portion of the intracellular loop of the renal
Na+/Ca2+ exchanger was amplified from cortical tissue and
single CTAL cells by reverse transcription-polymerase chain
reaction, using primers flanking the alternative splicing site.
Southern hybridization and DNA sequencing demonstrated
the isoform contained exons B and D, which is characteristic
of one isoform (NACA3) of the renal Na+/Ca2+ exchanger. The
results provide both functional and molecular evidence for a
Na+/Ca2+ exchanger in thick ascending limb cells of the
porcine kidney.
intracellular cal

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