Abstract
We have documented that both receptors of angiotensin II (ANG II) (AT1 and AT2) are
involved in regulation of intracellular signals in glomerular epithelial cells (GECs).
We studied the role of these receptors in regulation of intracellular ionized calcium
[Ca2+]i in GECs. Cells were loaded with Indo-1 (Ca2+) and SNARF-1 (pH) fluorescent dyes and then incubated with or without ANG II for
1 hour at 37°C. In some experiments AT1 and AT2 receptor blockers (Losartan and PD 12339, respectively) were added. In additional
experiments cells were incubated with thapsigargin (Tg) and bradykinin (BK) as well
as ANG II. A four-channel fluorescence videomicroscope system was used to measure
real-time [Ca2+ ]i in individual cells. Levels of inositol triphosphate (IP3) were measured with radioimmunoassay. An amount of 100 nmol/L of ANG II caused a
maximal increase in [Ca2+]i in calcium-containing buffer. ANG II had no effect on intracellular pH of GECs.
Increase in [Ca2+]i by ANG II was prevented by the concurrent use of Losartan and PD 123319. BK caused
a transient increase in [Ca2+]i, which was significantly decreased by ANG II; concurrent addition of Losartan and
PD 123319 prevented ANG II effect. ANG II prevented the accumulation of Ca2+ in intracellular stores. ANG II caused a significant but transient increase in levels
of IP3. In summary, ANG II increases extracellular/intracellular calcium dependent bidirectional
Ca2+ transport in GECs, inhibits BK induced release of Ca2+ from IP3 sensitive stores, and, in addition, reduces refilling of endoplasmic reticulum [Ca2+] depleted by repeated BK stimulation. Both receptor subtypes appear to be important
in ANG II mediated physiologic responses of GECs and may participate in modulation
of glomerular function in vivo. (J Lab Clin Med 2001;138:40-9)
Abbreviations:
ANG II (angiotensin II), AT1 and AT2 (angiotensin II receptor subtypes), BK (bradykinin), [Ca2+]i (intracellular ionized calcium), Δ[Ca2+]I (calcium peak height), DMEM (Dulbecco’s modified Eagle’s medium), EGTA (ethyleneglycol-bis-(β-aminoethylether)-N,N,N′,N′-tetraacetic acid), ER (endoplasmic reticulum), GEC (glomerular epithelial cell), GFR (glomerular filtration rate), HEPES (N-2-hydroxyethylpiperazine-N-2-ethanesulfonic), IP3 (inositol triphosphate), MDCK (Madin-Darby canine kidney), pH1 (intracellular pH), RPF (renal plasma flow), Tg (thapsigargin)To read this article in full you will need to make a payment
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References
- Structure and function of podocytes: an update.Anat Embryol. 1995; 192: 385-387
- Structural determinants of glomerular hydraulic permeability.Am J Physiol. 1994; 266: F1-F12
- In vitro effects of angiotensin II on glomerular function.Am J Physiol. 1986; 251: F627-F634
- Glomerular effects of angiotensin II require intra renal factors.Am J Physiol. 1990; 258: F717-F721
- Angiotensin II receptor subtypes in the kidney.J Am Soc Nephrol. 1993; 3: 1643-1652
- The intra renal rennin-angiotensin system.Semin Nephrol. 1993; 13: 13-30
- Angiotensin II receptor subtypes in cultured rat renal mesangial cells.Am J Physiol. 1992; 263: F411-F416
- Cloning of a rabbit kidney cortex AT1 angiotensin II receptor that is present in proximal tubule epithelium.Am J Physiol. 1993; 264: F645-F654
- Localization of angiotensin II type 1 receptor subtype mRNA in rat kidney.Am J Physiol. 1995; 268: F220-F226
- Documentation of angiotensin II receptors in glomerular epithelial cells.Am J Physiol. 1998; 274: F623-F627
- Angiotensin II receptor subtypes are coupled with distinct signal transduction mechanisms in neurons and astrocytes from rat brain.Proc Natl Acad Sci U S A. 1991; 88: 7567-7571
- Expression of AT2 receptors in the developing rat fetus.J Clin Invest. 1991; 88: 921-933
- Vasoactive substances induce cytoskeletal changes in cultured rat glomerular epithelial cells.J Am Soc Nephrol. 1992; 3: 1131-1138
- Angiotensin II increases the cytosolic activity in rat podocytes in culture.Kidney Int. 1997; 52: 687-693
- Angiotensin II increases the intracellular calcium activity in podocytes of the intact glomerulus.Kidney Int. 2000; 57: 41-49
- The inositol phosphate-calcium signaling system in nonexcitable cells.Endocr Rev. 1993; 14: 610-631
- Participation of protein kinase C in desensitization to bradykinin and to carbachol in MDCK cells.Am J Physiol. 1992; 262: F406-F499
- Effect of bradykinin on the cytosolic free calcium activity and phosphoinositol turnover in human glomerular epithelial cells.Renal Physiol Biochem. 1992; 15: 277-288
- Maintenance of bradykinin induced intracellular calcium response of MDCK cells depends on extracellular calcium.J Lab Clin Med. 1995; 125: 470-478
- High glucose alters actin assembly in glomerular mesangial and epithelial cells.Lab Invest. 1995; 73: 372-383
- Isolation and characterization of rat glomerular epithelial cells in vitro.Kidney Int. 1978; 14: 21-30
- Angiotensin II reduces [Ca2+]i stores and bradykinin(BK) induced [Ca2+]i in glomerular epithelial cells.in: XVIII Meeting, American Section, International Society for Heart Research, Chicago, Ill,June 9-13, 1996
- Simultaneous imaging of intracellular [Ca2+] and pH in single MDCK and glomerular epithelial cells.Am J Physiol. 1993; 265: C1184-C1190
- Simultaneous imaging of intra-cellular [Ca2+] and pH in single cells.Int Rev Exp Pathol. 1996; 36: 175-195
- Role of Ca2+-ATPases in regulation of cellular Ca2+ signaling, as studied with the selective microsomal Ca2+-ATPase inhibitor, thapsigargin.Agents Actions. 1990; 29: 8-15
- Angiotensin II mediates a sustained rise in nuclear and cytoplasmic calcium via multiple receptor subtypes.Am J Physiol. 1995; 269: H565-H570
- Angiotensin-induced cyclic GMP production is mediated by multiple receptor subtypes and nitric oxide in N1E-115 neuroblastoma cells.J Neurochem. 1992; 58: 1960-1963
Article info
Publication history
Accepted:
March 6,
2001
Received in revised form:
February 6,
2001
Received:
September 15,
2000
Footnotes
☆Supported by NIH grant RO1 AM-22040.
☆☆Reprint requests: Ram Sharma, PhD, Research Scientist, Room # 466 c MEB CVRC/Nephrology, Medical College of Wisconsin, 87 Watertown Plank Rd, Milwaukee, WI 53226.
Identification
Copyright
© 2001 Mosby, Inc. Published by Elsevier Inc. All rights reserved.
