Influence of purines and pyrimidines on circular muscle of the rat proximal stomach.
The effects of UTP were examined to characterize the receptor subtypes for UTP in the circular smooth muscle of the rat proximal stomach. The rank order of potency for contraction was 2-methylthio ATP > > ATP > or = UDP = UTP > or = adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S) > > UMP > CTP = alpha,beta-methylene ATP > adenosine = uridine. In tissues contracted by acetylcholine, ATP, 2-methylthio ATP, alpha,beta-methylene ATP and adenosine each caused relaxation. alpha,beta-Methylene ATP had the most potent effect and UTP caused only a small relaxation. Suramin inhibited ATP- and UTP-induced contractions. The contractile responses to ATP decreased in tissues desensitized with UTP, ATP-gamma-S and 2-methylthio ATP, but not with alpha,beta-methylene ATP. However, UTP-induced contraction was not inhibited by desensitization with ATP, alpha,beta-methylene ATP, ATP-gamma-S and 2-methylthio ATP. These results suggest that UTP causes contraction via receptors different from common P2 purinoceptors. These receptors are blocked by suramin in the rat proximal stomach.
Otsuguro
K
K
Laboratory of Pharmacology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Ito
S
S
Ohta
T
T
Nakazato
Y
Y
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D011687:Purines / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013270:Stomach / Q000187:drug effects*; D013498:Suramin / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology
D058913:Purinergic Agonists; D058914:Purinergic Antagonists; D011687:Purines; D011743:Pyrimidines; D013498:Suramin; D000255:Adenosine Triphosphate; D002118:Calcium; D014544:Uridine Triphosphate