Role of calcium and calmodulin in reaction of gastric fundus contraction
Journal Title: Advances in Hygiene and Experimental Medicine - Year 2011, Vol 65, Issue 0
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 µM 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 EC50 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.
Authors and Affiliations
Marta Gajdus, Leszek Szadujkis-Szadurski, Rafał Szadujkis-Szadurski, Izabela Glaza, Magdalena Zalewska, Katarzyna Szadujkis-Szadurska, Natalia Gurtowska
Keywords
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