Effects of purinergic analogues on spontaneous contraction and electrical activities of gastric antral circular muscle in guinea-pig.
- Author:
Zheng JIN
1
;
Hui-Shu GUO
;
Dong-Yuan XU
;
Ming-Yu HONG
;
Xiang-Lan LI
;
Wen-Xie XU
Author Information
1. Department of Physiology, Medical School, Shanghai Jiao Tong University, Shanghai 200030, China.
- Publication Type:Journal Article
- MeSH:
Adenosine Triphosphate;
analogs & derivatives;
pharmacology;
Animals;
Electrophysiology;
Guinea Pigs;
In Vitro Techniques;
Microelectrodes;
Muscle Contraction;
drug effects;
physiology;
Muscle, Smooth;
drug effects;
physiology;
Purinergic Agonists;
Pyloric Antrum;
drug effects;
physiology;
Thionucleotides;
pharmacology
- From:
Acta Physiologica Sinica
2004;56(6):678-684
- CountryChina
- Language:Chinese
-
Abstract:
In order to investigate the role of non-adrenergic non-cholinergic nerves in regulating mechanical and electrical activity of gastric circular smooth muscle, the effects of ATP and its analogues on gastric motility and electrical activities were observed in guinea-pig. In organ bath system, isometric force of the circular smooth muscle of guinea-pig gastric antrum was measured. Electrical activity of the muscle was recorded by using intracellular microelectrode. Electrical and mechanical activities were recorded by chart recorder. ATP and 2-MeSATP potentiated the mechanical activity but did not affect electrical activity in gastric circular smooth muscle. ATP and 2-MeSATP-induced contraction was effectively blocked by nonselective P2y-purinoceptor antagonist, reactive-blue-2 and suramin, but ATP-induced contraction was not blocked by alpha,beta-MeATP-induced desensitization of P2x-purinoceptors. However, alpha,beta-MeATP, P2x-purinoceptor agonist, attenuated slow waves with membrane hyperpolarization and inhibited contraction. The relaxation by beta,gamma-MeATP was blocked by alpha,beta-MeATP-induced desensitization of P2x-purinoceptors. ATP-induced contraction was blocked by external calcium-free, but not by nicardipine, a L-type calcium channel blocker. Indomethacin, a nonselective cyclooxygenase inhibitor, did not block ATP-induced contraction. The results suggest that: (1) ATP- and analogues-induced contraction is mediated by P2y-purinoceptor, whereas alpha,beta-MeATP-induced relaxation by P2x-purinoceptor in guinea-pig gastric antral circular smooth muscle. (2) ATP-induced contraction is dependent on extracellular calcium, but Ca2+ entry is not mediated by L-type calcium channel. (3) Prostaglandins are not involved in ATP- and analogue-induced contraction of gastric circular smooth muscle in guinea-pigs, and alpha,beta-MeATP-induced relaxation is related to membrane hyperpolarization.
