Role of calcium and calmodulin in reaction of gastric fundus contraction.

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Gajdus M, Szadujkis-Szadurski L, Szadujkis-Szadurski R, Glaza I, Zalewska M, Szadujkis-Szadurska K, Gurtowska N

Role of calcium and calmodulin in reaction of gastric fundus contraction.

Postepy Hig Med Dosw (Online). 2011 Sep 5;65:569-73. doi: 10.5604/17322693.958061.

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21918260 [ View in PubMed

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Abstract

BACKGROUND: The subject of this study is determination of the influence of calmodulin and calcium on gastric fundus smooth muscle contraction. During experiments, the author tested the influence of a serotonin receptor agonist, serotonin (5-HT), causing smooth muscle contraction. MATERIAL/METHODS: Testing was conducted on tissues isolated from rat's stomach. Male Wistar rats with weight between 220 g and 360 g were anesthetized by intraperitoneal injection of urethane (120 mg/kg). The stomach was dissected, and later the gastric fundus was isolated. Tissue was placed in a dish for insulated organs with 20 ml in capacity, filled with Krebs fluid. Results contained in the study are average values +/- SE. In order to determine statistical significance, the principles of receptor theory were used (Kenakin modification). RESULTS: According to conducted tests, we can deduce that 8 Br cGMP stops the reaction of gastric fundus smooth muscle contraction induced by serotonin. The use of 8Br-cGMP in the range of concentrations between 10 and 300 microM leads to reduction of maximum effect from 100% to 46%. Similar changes were obtained after the use of guanylate cyclase activator (CG) - YC-1. Curves for the contractile activity of serotonin along with an increase of concentration YC-1 are shifted to the right, and the maximum effect of reaction decreases. Increasing concentrations of flunarizine, a calmodulin antagonist, in a concentration-dependent way blocks binding between calcium and calmodulin, and at the same time leads to the shift of concentration-effect curves for serotonin to the right and a decrease of maximum reaction. Increasing concentrations of ODQ, a guanylate cyclase inhibitor lead to statistically significant shift of the curves to the left, decrease of EC(50) value and simultaneous increase of maximum reaction to serotonin. CONCLUSIONS: According to conducted testing, serotonin causes gastric fundus smooth muscle contraction dependent on concentration. Reaction of contraction induced by serotonin is stopped by a calmodulin antagonist, flunarizine. In addition, experiments confirmed participation of cyclical nucleotides in blocking reaction of gastric fundus contraction.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Flunarizine	Calmodulin	Protein	Humans	Yes	Antagonist	Details