1. Ca2+ signaling induced by sphingosylphosphorylcholine and sphingosine 1-phosphate via distinct mechanisms in rat glomerular mesangial cells 
Peng-Fei Chen, Ting-Yu Chin, Sheau-Huei Chueh 
Kidney International 
Volume 54, Issue 5, Pages (November 1998)
DOI: /j x
Copyright © 1998 International Society of Nephrology Terms and Conditions

2. Figure 1
Homologous desensitization of the SPC-, S1P-, ATP- or Ang II-induced [Ca2+]iincrease in rat glomerular mesangial cells. SPC 5 μm (trace a), S1P 5 μm (trace b), ATP 100 μm (trace c) or Ang II 90nm (trace d) were added at the indicated time to fura-2-loaded mesangial cells. Changes in [Ca2+]i were measured in the presence of extracellular Ca2+. The results shown are representative of 12 experiments. Abbreviations are in the Appendix.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

3. Figure 2
Heterologous desensitization of ATP- or Ang II-induced [Ca2+]iincreases in glomerular mesangial cells. (A) Fura-2-loaded suspension cells were initially exposed to 5 μm SPC (traces a and d), 5 μm S1P (traces b and e), 90nm Ang II (trace c) or 100 μm ATP (trace f). After 150 seconds, 100 μm ATP (traces a – c) or 90nm Ang II (traces d – f) were added, as indicated. The experiments were repeated a minimum of 6 times with similar results. (B) The statistical data for the [Ca2+]i changes induced by ATP or Ang II are summarized. The maximal [Ca2+]i increase induced by initial exposure to 100 μm ATP or 90nm Ang II (243 ± 23nm (N = 18) and 214 ± 17nm (N = 12), respectively) were taken as 100%. The data are the mean ± sd of 6 to 16 independent experiments. (C) Similar experiments were performed as in (A) using attached single cells. [Ca2+]i was expressed as the fluorescence ratio of 340 and 380nm.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

4. Figure 3
Effect of initial exposure to ATP or Ang II on the subsequent SPC- or S1P-induced [Ca2+]iincrease in glomerular mesangial cells. (A) SPC (5 μm) (traces a and b) or S1P (5 μm) (traces c and d) was added, as indicated, in the presence of extracellular Ca2+, after initial exposure of the cells to ATP (100 μm) (traces a and c) or Ang II (90nm) (traces b and d). (B) The statistical data for the [Ca2+]i changes induced by SPC or S1P are summarized. The maximal [Ca2+]i increase induced by an initial exposure to 5 μm SPC or 5 μm S1P (315 ± 27nm (N = 31) and 261 ± 14nm (N = 21), respectively) was taken as 100%. The data are the mean ± sd of 6 to 14 independent experiments.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

5. Figure 4
Effect of extracellular Ca2+and toxin pretreatment on agonist-induced arachidonic acid release in mesangial cells. Prelabeled mesangial cells were stimulated with buffer (•), 90nm Ang II (▾), 100 μm ATP (▿), 5 μm S1P (▪) or 5 μm SPC (□) in normal Ca2+-containing (A) or nominally Ca2+-free (B) extracellular solution. The release of radioactivity into the extracellular solution was assayed at different time. Similar experiments were performed using cells pretreated with 100ng/ml pertussis toxin (C), 1 μg/ml cholera toxin (D) or 3 μm AACOCF3 for 15hours, 15hours or three minutes, respectively. The results are expressed as the percentage of total radioactivity incorporated into the cells subtraction the basal value at t = 0. The data are the mean ± sd of 5 to 9 independent experiments.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

6. Figure 5
Effect of extracellular Ca2+, phospholipase A2inhibitor, pertussis toxin or cholera toxin on agonist-induced IP3generation in mesangial cells. IP3 generation was measured in control cells (A) or cells pretreated with 3 μm AACOCF3 for three minutes (C and D) or 100ng/ml pertussis toxin (E) or 1 μg/ml cholera toxin (F) for 15hours. Aliquots of cells (0.5mg of cell protein) were stimulated with buffer, 5 μm SPC, 5 μm S1P, 100 μm ATP and 90nm Ang II at 37°C for 15 seconds. In some experiments, extracellular Ca2+ was removed (B and D). IP3 was then extracted and determined using a radioreceptor assay. The data are the mean ± sd values of 5 to 7 independent experiments. An asterisk represents P < The number sign (E) indicates a significant decrease in IP3 generation after pertussis toxin pretreatment (P < 0.001).
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

7. Figure 6
Effect of preincubation of cells with phospholipase A2inhibitor on agonist-induced Mn2+influx. After preincubation with (traces f – j), or without, 3 μm AACOCF3 (traces a – e) for three minutes, fura-2-loaded mesangial cells were suspended in loading buffer containing 0.2mm Ca2+, then 1mm Mn2+ (Mn), 1mm Mn2+ plus 5 μm SPC (Mn + SPC), 1mm Mn2+ plus 5 μm S1P (Mn + S1P), 1mm Mn2+ plus 100 μm ATP (Mn + ATP) or 1mm Mn2+ plus 90nm Ang II (Mn + Ang II) was added and the fluorescence quench due to Mn2+ influx was measured. The experiment was repeated 11 times with similar results; one representative result is shown.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

8. Figure 7
Arachidonic acid-induced [Ca2+]iincrease in mesangial cells. Fura-2-loaded cells were suspended in either normal Ca2+-containing (trace a) or nominally Ca2+-free (trace b) loading buffer and [Ca2+]i changes were monitored in response to the addition of 10 μm arachidonic acid, as indicated by arrowheads. The experiment was repeated 8 times, using different batches of cells, with similar results. One representative result is shown.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

9. Figure 8
Effect of phospholipase A2-dependent Ca2+influx on heterologous desensitization of [Ca2+]iincreases induced by SPC, S1P, ATP or Ang II in mesangial cells. (A) In nominally Ca2+-free buffer, fura-2-loaded cells were initially exposed to 5 μm SPC (traces a and e), 5 μm S1P (traces b and f), 100 μm ATP (traces c and d) or 90nm Ang II (trace g and h). After 90 seconds, 100 μm ATP (traces a and b), 90nm Ang II (traces e and f), 5 μm SPC (traces c and g) or 5 μm S1P (traces d and h) was added, as indicated. (B) Similar experiments were performed as in (A) excepted that cells had been exposed to 3 μm AACOCF3 for three minutes and cells were suspended in normal Ca2+ containing buffer prior to the experiment. The experiments were repeated a minimum of 6 times with similar results.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

10. Figure 9
[Ca2+]ichanges induced by SPC, S1P, ATP or Ang II measured while phospholipase A2-dependent Ca2+influx is blocked. The statistical data observed in Figure 8 are summarized. The data are the mean ± sd of 10 independent experiments.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

11. Figure 10
Effect of AACOCF3and bromoenol lactone on SPC- and S1P-induced [Ca2+]iincrease. After initial exposure cells to 3 μm AACOCF3 and 10 μm bromoenol lactone (AACOCF3 + HELSS), 5 μm SPC (traces a and c), 5 μm S1P (traces b and d), 100 μm ATP (traces a and b) or 90nm Ang II (traces c and d) were added as indicated. The experiments were repeated 8 times with similar results; one representative result is shown.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

12. Figure 11
Effect of phospholipase A2inhibitior on agonist-induced IP3generation. IP3 generation was measured in control cells (A) or cells pretreated with 3 μm AACOCF3 for three minutes (B and C). Aliquots of cells (0.5mg of cell protein) were stimulated with buffer (○), 5 μm SPC (•), 5 μm S1P (▿), 100 μm ATP (▾) or 90nm Ang II (□) alone (A and B), or together with 10 μm arachidonic acid (C) for indicated time. IP3 was then extracted and determined using a radioreceptor assay. The data are the mean ± sd values of 5 independent experiments.
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions

13. Kidney International 1998 54, 1470-1483DOI: (10. 1046/j. 1523-1755
Kidney International  , DOI: ( /j x)
Copyright © 1998 International Society of Nephrology Terms and Conditions