Mediation of the vasoactive properties of diadenosine tetraphosphate via various purinoceptors.
OBJECTIVE
The vasoactive properties of P1,P4-diadenosine tetraphosphate (Ap4A) were studied by measuring the effects of perfusion pressure of a rat isolated perfused kidney.


RESULTS
The vasoconstrictive response to Ap4A was mediated to a large extent to a P2X receptor which could be shown by inhibition with pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid tetrasodium. The remaining vasoconstriction of Ap4A could be blocked by a 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective A1 receptor antagonist In raised tone preparation Ap4A evoked vasodilation when P2 receptors were blocked by suramin. The dilation was not mediated by a P2Y receptor as the effect could not be blocked by suramin.


CONCLUSIONS
Ap4A induces vasoconstriction via A1 and P2X receptors and vasodilatation via an unidentified receptor which is not a P2Y receptor. Ap4A may play an important role in kidney perfusion and, thus, in blood-pressure control.
van der Giet
M
M
Ruhr-Universität Bochum, Universitätsklinikum, Medizinische Klinik I, Herne, Germany.
Jankowski
J
J
Schlüter
H
H
Zidek
W
W
Tepel
M
M
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide) / Q000494:pharmacology; D000818:Animals; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D010477:Perfusion; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D011983:Receptors, Purinergic / Q000187:drug effects* / Q000502:physiology*; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000502:physiology; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000502:physiology; D012077:Renal Artery / Q000187:drug effects / Q000502:physiology; D013873:Thionucleotides / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014665:Vasodilator Agents / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
D015226:Dinucleoside Phosphates; D011983:Receptors, Purinergic; D018047:Receptors, Purinergic P1; D018048:Receptors, Purinergic P2; D013873:Thionucleotides; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D014970:Xanthines; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D019830:Adenosine-5'-(N-ethylcarboxamide); C020733:diadenosine tetraphosphate; D011732:Pyridoxal Phosphate; D000255:Adenosine Triphosphate; C051360:1,3-dipropyl-8-cyclopentylxanthine; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; C008501:2-methylthio-ATP