Effects of adenosine analogues on ADP ribosylation of GS protein in coronary artery.
The coupling of adenosine receptor(s) to G proteins was investigated in bovine coronary artery smooth muscle membranes. Western blotting of membrane proteins with specific antisera confirmed the presence of 45- and 52-kDa proteins as alpha-subunits of stimulatory (Gs) protein. Cholera toxin (CT) also ADP ribosylated 45- and 52-kDa proteins. Guanosine 5'-O-(3-thiotriphosphate) (10 nM to 10 microM) stimulated the CT-induced ribosylation, suggesting that the ribosylation can be modulated by the activation of G proteins. 2-Chloroadenosine and (R)-phenylisopropyladenosine produced a concentration (10(-7) to 10(-4) M)-dependent increase in CT-induced ribosylation. These responses were completely blocked by adenosine receptor antagonist 8-sulfophenyltheophylline (10 microM). 5'-(N-ethylcarboxamido)adenosine (NECA) alone or in the presence of 8-cyclopentyl-1,3-dipropylxanthine (50 nM) did not affect the ribosylation. Furthermore, NECA did not counter the effects of 2-chloroadenosine and isoproterenol on CT-induced ribosylation. The data provide evidence for the adenosine receptor(s) coupling to Gs proteins and further suggest a different site or mechanism for the action of NECA in bovine coronary artery.
Hussain
T
T
Department of Pharmacology, School of Medicine, East Carolina University, Greenville, North Carolina 27858-4354.
Mustafa
S J
SJ
D015762:2-Chloroadenosine / Q000494:pharmacology; D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D019830:Adenosine-5'-(N-ethylcarboxamide); D000818:Animals; D015153:Blotting, Western; D002417:Cattle; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002772:Cholera Toxin / Q000378:metabolism* / Q000494:pharmacology; D003331:Coronary Vessels / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology
D008565:Membrane Proteins; D011983:Receptors, Purinergic; D015762:2-Chloroadenosine; D000246:Adenosine Diphosphate Ribose; D019830:Adenosine-5'-(N-ethylcarboxamide); D006160:Guanosine Triphosphate; D002772:Cholera Toxin; D019204:GTP-Binding Proteins; D000241:Adenosine; D007545:Isoproterenol