![Fig. 3. Effect of chelating agents on [Ca++]i elevations dependent on the interaction between GPIbα and A1VWF. / A blood cell suspension prepared as described in the legend for Figure2 was perfused over immobilized VWF at the indicated shear rates for 90 seconds. Interacting platelets were identified and analyzed as described in the legend for Figure 2. (A) After addition of the membrane-impermeable Ca++ chelator EGTA (2 mM), no type γ [Ca++]i oscillations (Figure 1) occurred, but α/β peaks were unchanged. In contrast, after addition of membrane-permeable BAPTA-AM, all [Ca++]i oscillations were obliterated. The same results were obtained in 3 different experiments. (B) After addition of EGTA (2 mM) and the anti-αIIbβ3monoclonal antibody LJ-CP8 (100 μg/mL), all the platelets interacting with the surface in a 30-second period after an initial 90-second perfusion were enumerated (●); the proportion of these showing α/β [Ca++]i elevations was calculated (▪). There were no γ peaks under these conditions. Results are the mean ± 95% CI from 3 separate experiments performed at the indicated shear rates between 500 and 20 000 seconds−1. (C) The peak [Ca++]i of type α oscillations was measured as a function of the shear rate during perfusion. Each point shows the mean ± 95% CI of at least 10 peaks and is representative of the results obtained in 3 different experiments using the same conditions described for panel B.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/100/8/10.1182_blood-2002-02-0514/4/h82023252003.jpeg?Expires=1735535917&Signature=VJsX18Gl5VJx2fMqBP-SOqtSbd3ZzkscWz9FGiDunB8NrrL1HQe77UVSPdszLeRX77uV0eFNgdcbyD~dwwDtTKoJc7ncT0oloaHXrfcjMvYmWjVIVcKlTMZ4-c0~gX6COZ7ywzhUdl~YN709fb-Ac4MkE88L6cI8tPpti4G3WoMfiLeyIj7zCPmdCPxjX7vWGE~rwWE7hLAqGGpdFJL7r~AxUv6bPRSBAU65ktxr15qWujxoFgQTh1ImZBKvWxR4hu3afCvlOMExPWF7Oi51Yf-qPTiKAQg9zX2s4OwPL2hyjqqZGEH7sbC8fbVZidrWaIpezTYhNzVmNIDqIx2k7g__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Effect of chelating agents on [Ca++]i elevations dependent on the interaction between GPIbα and A1VWF.
A blood cell suspension prepared as described in the legend for Figure2 was perfused over immobilized VWF at the indicated shear rates for 90 seconds. Interacting platelets were identified and analyzed as described in the legend for Figure 2. (A) After addition of the membrane-impermeable Ca++ chelator EGTA (2 mM), no type γ [Ca++]i oscillations (Figure 1) occurred, but α/β peaks were unchanged. In contrast, after addition of membrane-permeable BAPTA-AM, all [Ca++]i oscillations were obliterated. The same results were obtained in 3 different experiments. (B) After addition of EGTA (2 mM) and the anti-αIIbβ3monoclonal antibody LJ-CP8 (100 μg/mL), all the platelets interacting with the surface in a 30-second period after an initial 90-second perfusion were enumerated (●); the proportion of these showing α/β [Ca++]i elevations was calculated (▪). There were no γ peaks under these conditions. Results are the mean ± 95% CI from 3 separate experiments performed at the indicated shear rates between 500 and 20 000 seconds−1. (C) The peak [Ca++]i of type α oscillations was measured as a function of the shear rate during perfusion. Each point shows the mean ± 95% CI of at least 10 peaks and is representative of the results obtained in 3 different experiments using the same conditions described for panel B.
