Volume 55, Issue 4, Pages 1359-1366 (April 1999) Lipoprotein(a) stimulates growth of human mesangial cells and induces activation of phospholipase C via pertussis toxin-sensitive G proteins  Ulrich F. Mondorf, Albrecht Piiper, Martina Herrero, Hans-Georg Olbrich, Michael Bender, Werner Gross, Ernst Scheuermann, Helmut Geiger  Kidney International  Volume 55, Issue 4, Pages 1359-1366 (April 1999) DOI: 10.1046/j.1523-1755.1999.00367.x Copyright © 1999 International Society of Nephrology Terms and Conditions

Figure 1 Concentration-dependent binding of [125I]Lp(a) by human mesangial cells. Unspecific binding was determined at 4°C and was subtracted. Data are given as means ± sd. Measurements were carried out in quadruplicate. Kd = 17.0 μg protein/ml. Bmax = 1014.6ng/mg protein. Kidney International 1999 55, 1359-1366DOI: (10.1046/j.1523-1755.1999.00367.x) Copyright © 1999 International Society of Nephrology Terms and Conditions

Figure 2 Effect of lipoprotein(a) [Lp(a)] on [3H]thymidine uptake (A) and tetrazolium uptake (B). Cells were incubated in the presence of 0.5% FCS (□) and the absence of FCS (fetal calf serum; ▀) and in the presence of the PLC (phospholipase C) inhibitor U73122 (1 μm) without FCS (▪). Data are given as means ± sd of 12 independent experiments. Asterisks indicate a significant increase as compared with the control experiments (*P < 0.001). Kidney International 1999 55, 1359-1366DOI: (10.1046/j.1523-1755.1999.00367.x) Copyright © 1999 International Society of Nephrology Terms and Conditions

Figure 3 Effect of Lp(a) on intracellular calcium concentration ([Ca2+]i) in Fura 2-loaded single human mesangial cells. Human mesangial cells grown on coverslips were loaded with Fura 2-AM for 30minutes at 37°C and were washed twice with Krebs-Henseleit-Hepes buffer immediately before the experiment. Lp(a) was added to the incubation medium containing 1mm Ca2+ [A, Lp(a) 5 μg/ml; B, Lp(a) 50 μg/ml]. The influence of the extracellular calcium concentration is illustrated in (C) [1 = addition of 50 μg/ml Lp(a)] and (D). The experiments shown in (A–C) are representative for 10 independent experiments. Data shown in panel D are means ± sd. Kidney International 1999 55, 1359-1366DOI: (10.1046/j.1523-1755.1999.00367.x) Copyright © 1999 International Society of Nephrology Terms and Conditions

Figure 4 Effect of Lp(a) and pertussis toxin on Lp(a)-induced inositol 1,4,5-triphosphate (1,4,5-IP3) production. Mesangial cells were incubated with (○) or without (⧫) pertussis toxin (0.2 μg/ml) for 12hours and were stimulated with Lp(a) (50 μg/ml) at 37°C for the indicated time. The amount of 1,4,5-IP3 was determined as described in Methods section. Data are expressed as the means of three independent experiments. The asterisk indicates a significant increase as compared to the initial value (*P < 0.001). Kidney International 1999 55, 1359-1366DOI: (10.1046/j.1523-1755.1999.00367.x) Copyright © 1999 International Society of Nephrology Terms and Conditions

Figure 5 Effect of pertussis toxin on [Ca2+]i variation in response to Lp(a) and vasopressin. Human mesangial cells were cells grown on coverslips and were preincubated with pertussis toxin (0.2 μg/ml) for 12hours. Cells were loaded with Fura 2-AM for 30minutes at 37°C and were washed twice with Krebs-Henseleit-Hepes buffer immediately before the experiment. Lp(a) (50 μg/ml) and vasopressin (100nm) were added to the cells. Fura 2 fluorescence of individual cells was monitored at room temperature. The experiment shown is representative for four independent observations. Kidney International 1999 55, 1359-1366DOI: (10.1046/j.1523-1755.1999.00367.x) Copyright © 1999 International Society of Nephrology Terms and Conditions