Interaction of beta-adrenoceptor and adenosine receptor agonists on phosphorylation. Identification of target proteins in mammalian ventricles.
The influence of the adenosine derivative (--)-N6-phenylisopropyladenosine (R-PIA, 1 micron) and 5'N-ethylcarbox-amidoadenosine (NECA, 1 micron) on beta-adrenergic stimulated (isoproterenol, 10 nM) phosphorylation of sarcolemmal (15 kDa protein), sarcoplasmic reticular (phospholamban) and myofibrillar proteins (troponin I, C-protein) was studied in isolated 32P-labeled guinea-pig ventricles. The identification of the 15 kDa protein, phospholamban, troponin I and C-protein was based on their reaction with specific antibodies. Isoproterenol increased contractile parameters (developed tension, rate of tension development, rate of relaxation) and stimulated the phosphorylation state of a 15 kDa protein (now named phospholemman), of phospholamban, troponin I and C-protein (regarded as regulatory proteins). Isoproterenol concomitantly increased myocardial cyclic AMP levels. R-PIA and NECA attenuated the effects of isoproterenol on contractile parameters as well as on the phosphorylation of the regulatory proteins without affecting cyclic AMP levels. The effects of 1 microM R-PIA and 1 microM NECA on the isoproterenol-stimulated phosphorylation of regulatory proteins were blocked by the adenosine receptor antagonist 1.3-dipropyl-8-cyclopentylxanthine (DPCPX, 1 microM). Therefore, it is concluded that adenosine derivatives acting via adenosine receptors can reduce the isoproterenol-stimulated phosphorylation state of the following regulatory proteins: phospholemman, phospholamban, troponin I and C-protein.
Krannert Institute of Cardiology, Indianapolis, Indiana, USA.
J
J
Neumann
R C
RC
Gupta
L R
LR
Jones
G S
GS
Bodor
S
S
Bartel
E G
EG
Krause
H T
HT
Pask
W
W
Schmitz
H
H
Scholz
A M
AM
Watanabe
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide); D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism; D002352:Carrier Proteins / Q000302:isolation & purification / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D006352:Heart Ventricles; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000378:metabolism*; D010660:Phenylisopropyladenosine / Q000494:pharmacology*; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D058906:Purinergic P1 Receptor Agonists; D012508:Sarcolemma / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D014336:Troponin / Q000302:isolation & purification / Q000378:metabolism; D019210:Troponin I; D000099211:Phospholamban
D000241:Adenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D000318:Adrenergic beta-Agonists; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D007545:Isoproterenol; D010660:Phenylisopropyladenosine; D010750:Phosphoproteins; D010761:Phosphorus Radioisotopes; D058906:Purinergic P1 Receptor Agonists; D014336:Troponin; D019210:Troponin I; D000099211:Phospholamban; C020723:citrate-binding transport protein