Effects of adenosine tetraphosphate (ATPP) on vascular tone in the isolated rat aorta.
Effects of a platelet-released, naturally occurring nucleotide, adenosine 5'-tetraphosphate (ATPP) on vascular tone were analyzed in the isolated rat aorta. Under resting tension ATPP (1 approximately 100 microM) elicited concentration-dependent contractions in endothelium-intact aortic rings in contrast to the concentration-dependent relaxation with ATP. In endothelium-denuded aortic rings, ATPP induced contraction, as ATP did, but with a greater potency. alpha, beta-methylene ATP (APCPP 50 microM), a P2x-purinoceptor antagonist, significantly inhibited ATPP- as well as ATP-induced contractions in the endothelium-denuded preparations suggesting that ATPP acts via P2x-purinoceptors. ATPP (10 approximately 100 microM) relaxed precontracted aortic rings with an intact endothelium in a concentration-dependent manner. This effect of ATPP was 3.7 fold less potent than that of ATP. However, after P2x-purinoceptor blockade, the effect became identical between the two nucleotides. Reactive blue 2, a selective antagonist of P2x-purinoceptors, significantly attenuated the ATPP-induced relaxation with no change in the ATP-induced relaxation. These results indicated that the rat aortic endothelium contains heterogeneous populations of P2-purinoceptors (possibly P2y and nucleotide receptors). Since ATPP shows dual effects depending upon the vascular tension, it may play a significant role in the physiological regulation of vascular tone.
Lee
J W
JW
Department of Physiology, Yonsei University Wonju College of Medicine, Kangwon-Do, Republic of Korea.
Kong
I D
ID
Park
K S
KS
Jeong
S W
SW
D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D015226:Dinucleoside Phosphates / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects
D015226:Dinucleoside Phosphates; D018048:Receptors, Purinergic P2; C020733:diadenosine tetraphosphate