Table 1.

Effect of second messenger inhibitors on phosphatidylserine (PS) exposure in red blood cells (RBCs) from sickle cell disease (SCD) patients

		[Ca2+]i (μM) in HK saline
		0	1	10	100	1000
Second messenger System	Inhibitor	% PS Exposure
Cyclooxygenase	Acetylsalicylic acid Control 200 μM (n = 3)	4 ± 0 4 ± 1	53 ± 11 55 ± 6	52 ± 7 58 ± 5	61 ± 6 58 ± 5	80 ± 6 82 ± 7
	Diclofenac Control 500 μM (n = 4)	4 ± 0 4 ± 1	31 ± 9 44 ± 7*	34 ± 5 47 ± 7*	45 ± 7 52 ± 3	68 ± 4 87 ± 2*
Platelet activating factor	ABT491 Control 50 μM (n = 3)	5 ± 2 4 ± 1	28 ± 2 29 ± 4	33 ± 6 42 ± 3	36 ± 2 44 ± 5	77 ± 2 72 ± 12
Phospholipase A2	Quinacrine Control 100 μM (n = 3)	2 ± 0 6 ± 1	25 ± 5 33 ± 5	29 ± 9 38 ± 5	36 ± 3 40 ± 2	67 ± 9 73 ± 4
Sphingomyelinase	3,4-Dichloro-isocoumarin Control 200 μM (n = 4) GW4869 Control 10 μM (n = 5)	4 ± 0 5 ± 0 3 ± 0 17 ± 5*	53 ± 7 49 ± 3 21 ± 6 50 ± 7*	51 ± 5 56 ± 3 30 ± 2 47 ± 10	61 ± 4 52 ± 5 33 ± 4 57 ± 5*	79 ± 6 81 ± 4 68 ± 8 77 ± 4

RBCs were treated with the ionophore bromo-A23187 (2.5–6 μM) for 30 min in HK saline in the absence of [Ca²⁺]_o and with [Ca²⁺]_o varied between 1 μM and 1 mM. Inhibitors were absent (controls) or added at the concentrations indicated for 30 min prior to, and during, ionophore treatment (0.5 % Hct, final [DMSO] <1 %). Values represent means ± SEM of percentage of RBCs with exposed PS for n individuals. * p < 0.05 compared to controls