Inotropic effects of diadenosine tetraphosphate in isolated canine cardiac preparations.
We studied the effects of diadenosine tetraphosphate (AP4A) on the force of contraction in canine preparations. The force of contraction was measured in isolated electrically driven (1 Hz) atrial and ventricular cardiac trabeculae from adult dogs. AP4A (100 microM) alone and after prestimulation with 10 nM isoproterenol reduced force of contraction in atrial preparations by approximately 24%. Moreover, AP4A (100 microM) alone and after prestimulation with 10 nM isoproterenol reduced the force of contraction in ventricular preparations by 29 and 29%, respectively. The negative inotropic effects of AP4A were abolished by the A1-adenosine receptor antagonist 1,3-dipropyl-cyclopentyl-xanthine (DPCPX). In summary, in canine myocardium, AP4A alone and after prestimulation with a beta-adrenoceptor agonist exerts negative inotropic effects, which are probably mediated via A1-adenosine receptors.
Neumann
J
J
Institut für Pharmakologie und Toxikologie, Universität Münster, Germany.
Meissner
A
A
Bokník
P
P
Gombosová
I
I
Knapp
J
J
Lüss
H
H
Müller
F U
FU
Schlüter
H
H
Zidek
W
W
Rolf
N
N
Van Aken
H
H
Vahlensieck
U
U
Schmitz
W
W
D000818:Animals; D016275:Atrial Function / Q000187:drug effects; D002316:Cardiotonic Agents / Q000494:pharmacology; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D004285:Dogs; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D058915:Purinergic P1 Receptor Antagonists
D002316:Cardiotonic Agents; D015226:Dinucleoside Phosphates; D010975:Platelet Aggregation Inhibitors; D058915:Purinergic P1 Receptor Antagonists; C020733:diadenosine tetraphosphate; D007545:Isoproterenol