The P2Z‐purinoceptor of human lymphocytes: actions of nucleotide agonists and irreversible inhibition by oxidized ATP

• Published in: British journal of pharmacology Vol. 112; no. 3; pp. 946 - 950
• Main Authors: Wiley, James S., Chen, Joan R., Snook, Marie B., Jamieson, Gary P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.1994; Nature Publishing
• Subjects: 2‐chloro ATP; 2‐methylthio ATP; Adenosine Triphosphate - pharmacology; Adenosinic and purinergic receptors; ATP‐receptor; Barium - metabolism; barium influx; benzoylbenzoic ATP; Biological and medical sciences; Calcium - metabolism; Cell receptors; Cell structures and functions; Culture Media; Cytosol - drug effects; Cytosol - metabolism; extracellular; Fluorometry; fluorosulphonylbenzoyladenosine; Fundamental and applied biological sciences. Psychology; human leukaemic; Humans; In Vitro Techniques; ion channel; Leukemia, Lymphocytic, Chronic, B-Cell - metabolism; lymphocyte; lymphocytes; Lymphocytes - drug effects; Lymphocytes - metabolism; Molecular and cellular biology; Oxidation-Reduction; oxidized ATP; P2Z‐purinoceptor; Potassium - pharmacology; Purine Nucleotides - pharmacology; Purinergic P2 Receptor Agonists; Purinergic P2 Receptor Antagonists; Sodium - pharmacology; Tumor Cells, Cultured; Characterization; Human; Agonist; Leukocyte; Electrophysiology; P2 Purinergic receptor; Ionic channel; Inhibition; Irreversible; ATP; In vitro; Lymphocyte
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.1994.tb13172.x

1 Extracellular adenosine triphosphate (ATP) is known to open a receptor‐operated ion channel (P2Z class) in human lymphocytes which conducts a range of cationic permeants. The activity of a range of different agonists and inhibitors towards the P2Z‐purinoceptor was investigated by measuring the agonist‐induced influx of Ba2+ into fura‐2 loaded lymphocytes. 2 The most potent agonist was 2′ & 3′‐0‐(4‐benzoylbenzoyl)‐ATP (benzoylbenzoic ATP) which gave 2 fold greater maximum Ba2+ influx and had a 10 fold lower EC50 than for ATP. The rank order of agonist potency in K+‐media was benzoylbenzoic ATP>>ATP = 2‐methylthio ATP = 2‐chloro ATP>ATP‐γ‐S. ADP, UTP and α,β‐methylene ATP were unable to stimulate Ba2+ influx. 3 Extracellular Na+ inhibited the increment of Ba2+ influx induced by all concentrations of ATP, 2‐methylthio ATP, 2‐chloroATP and ATP‐γ‐S. This inhibitory effect of extracellular Na+ is also reflected in the different EC50s for benzoylbenzoic ATP (8 μm in K+‐media, 18 μm in Na+‐media) but the maximal response to this agonist was the same in the presence or absence of Na+. 4 Treatment of lymphocytes with 2,3 dialdehyde ATP (oxidized ATP) at 300 μm for 60 min gave total and irreversible inhibition of ATP‐induced Ba2+ influx. 5′‐p‐Fluorosulphonyl benzoyladenosine (FSBA) also was an irreversible inhibitor but the maximal inhibition achieved was 90%. 5 It is concluded that the P2Z‐purinoceptor of human lymphocytes has a rank order of agonist potency which clearly distinguishes it from other P2‐receptors and that oxidized ATP is a convenient irreversible inhibitor for the P2Z‐purinoceptor.