P2X7 receptor activation causes phosphatidylserine exposure in canine erythrocytes

Figure 1 ATP induces phosphatidylserine exposure in erythrocytes from multiple dog breeds. Erythrocytes, from 17 pedigree and eight crossbreed (X) dogs, in NaCl medium were incubated for 24 h at 37 °C in the absence or presence of 1 mmol/L ATP. Cells were labeled with FITC-conjugated Annexin V and analyzed by flow cytometry. The bars represent group means (A and B). A: The symbols represent the percentage of Annexin V⁺ erythrocytes, from each dog, following incubation in the absence (basal) or presence of ATP; ^bP < 0.0001 ATP vs basal; B: The symbols represent the percentage of ATP-induced PS exposure in erythrocytes, from each dog, determined as the difference in the percentage of Annexin V⁺ erythrocytes following incubation in the presence and absence of ATP. The broken line represents the mean ATP-induced PS exposure from all dogs. The symbols for Staffordshire bull terrier X represent a Staffordshire bull terrier and Australian kelpie cross, Staffordshire bull terrier and bull terrier cross, or a Staffordshire bull terrier cross. PS: Phosphatidylserine.

Figure 2 ATP induces phosphatidylserine exposure in canine erythrocytes in a concentration-dependent manner. Erythrocytes in NaCl medium were incubated for 24 h at 37 °C in the absence or presence of ATP (A) or 1 mmol/L nucleotide (B and C) (as indicated). Prior to ATP incubation, cells were pre-incubated for 15 min in the absence or presence of 10 µmol/L AZ10606120 (AZ10) or 10 µmol/L NF499 (C). Following nucleotide incubation, cells were labeled with FITC-conjugated Annexin V and analyzed by flow cytometry (A-C). A: The data represent percent maximum response to 2 mmol/L ATP (mean ± SD, n = 4 dogs); B: The data represent mean ± SD (n = 5 dogs); ^bP < 0.001 ATP vs basal; ^dP < 0.001 AMP vs ATP; ^fP < 0.001 ADP vs ATP; C: The data represent mean ± SD (n = 5 dogs); ^bP < 0.001 ATP vs basal; ^dP < 0.001 ATP with NF449 vs NF449; ^fP < 0.001 ATP with AZ10606120 vs ATP.