Involvement of Spontaneously Formed Cyclic Nucleotides in Cat Gastric Muscle Relaxation .
- Author:
Sang Soo SIM
1
;
Hye Jung BAEK
;
Duck Joo RHIE
;
Shin Hee YOON
;
Sang June HAHN
;
Yang Hyeok JO
;
Myung Suk KIM
Author Information
1. Department of Physiology, College of Medicine, Catholic University of Korea, 505 Banpo-dong, Socho-gu, Seoul, 137-701 South Korea.
- Publication Type:Original Article
- Keywords:
Smooth muscle relaxation;
Cyclic AMP;
Cyclic GMP;
Cat stomach
- MeSH:
1-Methyl-3-isobutylxanthine;
Adenylyl Cyclases;
Animals;
Cats*;
Cyclic AMP;
Cyclic GMP;
Guanylate Cyclase;
Isoproterenol;
Methylene Blue;
Muscle Cells;
Muscle Contraction;
Muscle Relaxation*;
Muscle, Smooth;
Nitroprusside;
Nucleotides, Cyclic*;
Relaxation;
Stomach;
Vasoactive Intestinal Peptide
- From:The Korean Journal of Physiology and Pharmacology
1999;3(3):275-282
- CountryRepublic of Korea
- Language:English
-
Abstract:
Muscle strips and muscle cells from cat stomach were used to investigate whether spontaneously formed cyclic nucleotides were involved in the inhibition of gastric smooth muscle contraction. A phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX), increased the levels of both cyclic GMP (cGMP) and cyclic AMP (cAMP) in resting state cells, while decreasing acetylcholine-induced muscle contraction. Under the influence of IBMX, SQ22536, an adenylyl cyclase inhibitor and methylene blue, a guanylyl cyclase inhibitor completely blocked increases in cAMP and cGMP respectively, without any effect on contraction. However, the combination of SQ22536 and methylene blue completely blocked increases in both cAMP and cGMP levels and stimulated contractions markedly even in the presence of IBMX. Muscle contraction inhibitors such as isoprenaline, vasoactive intestinal polypeptide and sodium nitroprusside also appeared to increase cyclic nucleotide levels which decreased contraction. Which nucleotide increased the most was dependent on the agonist used. Therefore, irrespective of the cyclic nucleotide class, the spontaneous formation of cyclic nucleotides should be considered in evaluating the mechanism of gastric smooth muscle relaxation.
