Adenosine; a physiologic modulator of superoxide anion generation by human neutrophils. Adenosine acts via an A2 receptor on human neutrophils.
Adenosine specifically inhibits superoxide anion generation by N-formyl-methionyl-leucyl-phenylalanine-stimulated neutrophils without affecting either degranulation or "aggregation." We present data that also supports the hypothesis that adenosine engages a specific cell surface receptor to mediate inhibition of stimulated neutrophils. Theophylline (10 and 100 mu M), a competitive antagonist at adenosine receptors, reversed the effects of adenosine (0.1 mu M) on superoxide anion generation by stimulated neutrophils. The adenosine analogue 5'N-ethylcarboxamidoadenosine (NECA) was a more potent inhibitor of superoxide anion generation than either N6-phenylisopropyladenosine (PIA) or adenosine, an order of potency consistent with that previously demonstrated for adenosine A2 receptors. 2-Chloroadenosine inhibited superoxide anion generation at concentrations similar to NECA. [3H]-NECA and [3H]-2-chloroadenosine bound to a single receptor on intact neutrophils. The characteristics of the receptors for [3H]-NECA and [3H]-2-chloroadenosine were similar (Kd = 0.22 and 0.23 mu M, respectively; number of binding sites = 9.31 and 11.1 X 10(3) sites/cell, respectively). NECA, 2-chloroadenosine, adenosine, and PIA inhibited binding of [3H]-NECA with a rank order similar to that for inhibition of superoxide anion generation (NECA = 2-chloroadenosine greater than adenosine greater than PIA). There was 50% inhibition of superoxide anion generation by NECA at approximately 20% receptor occupancy. Adenosine, derived from damaged tissues, may serve as a specific, endogenous modulator of superoxide anion generation by activated neutrophils through interaction at this newly described receptor on human neutrophils.
Cronstein
B N
BN
Rosenstein
E D
ED
Kramer
S B
SB
Weissmann
G
G
Hirschhorn
R
R
D015762:2-Chloroadenosine; D000241:Adenosine / Q000031:analogs & derivatives / Q000378:metabolism / Q000502:physiology*; D019830:Adenosine-5'-(N-ethylcarboxamide); D001665:Binding Sites / Q000187:drug effects; D001667:Binding, Competitive; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000032:analysis / Q000187:drug effects / Q000502:physiology*; D011983:Receptors, Purinergic; D013481:Superoxides / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D013806:Theophylline / Q000494:pharmacology
D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D013481:Superoxides; D015762:2-Chloroadenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D009240:N-Formylmethionine Leucyl-Phenylalanine; D013806:Theophylline; D000241:Adenosine