Baris Karadas

Effects of nimesulide and pentoxifylline on decreased contractile responses in rat ileum with peritonitis.

The aim of this study was to determine the effects of nimesulide and pentoxifylline on the contractile effects of KCl, carbachol and substance P in the longitudinal muscle of rat ileum during peritonitis. Peritonitis was induced in rat ileum by cecal ligation and puncture. Thirty rats were operated on to induce peritonitis, 10 of which received nimesulide (5 mg/kg, subcutaneously) and 10 of which received pentoxifylline (25 mg/kg, subcutaneously) before the operation; 10 other rats underwent a sham operation and acted as controls. Twenty-four hours after the operation, ileum segments were transferred to isolated organ baths and responses to KCl, carbachol and substance P were recorded. Emax values of KCl, carbachol and substance P were markedly lower (P<0.05), with no change in the pD2 values, in the peritonitis group than in the controls. Peritonitis-induced changes in the KCl, carbachol and substance P responses of ileum were significantly restored by nimesulide (P<0.05), but not by pentoxifylline. The improved contractile responses following nimesulide treatment indicate that products of cyclooxygenase-II may be, at least in part, responsible for the decreased contractile responses to KCl, carbachol and substance P in peritonitis.

Comparative relaxant effects of YC-1 and DEA/NO on the sheep sphincter of Oddi

Background/Aims: Nitric oxide (NO) is a major inhibitor in various parts of the gastrointestinal tract. This study was designed to compare the effects of YC-1, NO-independent soluble guanylate cyclase (sGC) activator, and DEA/NO, NO-nucleophile adduct, on sheep sphincters of Oddi (SO). Methods: SO rings were mounted in a tissue bath and tested for changes in isometric tension in response to 3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole (YC-1, 10^–10–10^–5M), diethylamine/NO complex (DEA/NO, 10^–8–10^–4M). We also evaluated the effect of YC-1 (10^–6 and 10^–5M) and DEA/NO (10^–5 and 10^–4M) on the levels cyclic GMP (cGMP) in isolated SO. Results: YC-1 (10^–10–10^–5 M) and DEA/NO (10^–8–10^–4M) induced concentration-dependent relaxation of isolated SO rings precontracted with carbachol (10^–6M). The pEC₅₀ value of DEA/NO was significantly lower than those for YC-1 (p < 0.05), with no change of E_max values. YC-1 increased cGMP levels more than control, carbachol and DEA/NO groups (p < 0.05). Conclusion: These results show that YC-1 is a more potent relaxant than DEA/NO and causes more elevation of cGMP levels in isolated SO rings.

DO ANTIBIOTICS CONTRIBUTE TO POSTOPERATIVE ILEUS? CONTRACTILE RESPONSES OF ILEUM SMOOTH MUSCLE IN GUINEA PIGS TO LONG-TERM PARENTERAL CEFTRIAXONE AND AMPICILLIN

Background:  Antibiotics may impair small bowel smooth muscle contractility and contribute to postoperative ileus. The aim of this study was to compare the contractile responses of ileum smooth muscle to different agonists in guinea pigs treated with ceftriaxone (Rocephin; F. Hoffman–La Roche, Kaiseraugst, Switzerland) or ampicillin (Ampisina; Mustafa Nevzat İlaç Sanayii AŞ, Istanbul, Turkey).

Effects of 5-nitro-2-(3-phenylpropylamino) benzoic acid, anthracene-9-carboxylate, and zaprinast on endothelin-1-induced contractions of pregnant rat myometrium

OBJECTIVE The effects of 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB), anthracene-9-carboxylate (9-AC) (chloride channel blockers) and zaprinast (an inhibitor of phosphodiesterase-5) on endothelin-1 (ET-1) induced contractions of pregnant rat myometrium were investigated in vitro. METHODS Isolated myometrial strips were obtained from pregnant rats, and the strips were mounted in organ baths for recording of isometric tension (n=8). The effects of 10(-7) to 10(-4)M NPPB, 10(-7) to 10(-4)M 9-AC, and 10(-7) to 10(-4)M zaprinast on 10(-8)M ET-1-induced contractions of pregnant rat myometrial smooth muscle were recorded. RESULTS NPPB and 9-AC increased the amplitude of ET-1-induced myometrial contractions, while decreasing the frequency, in a concentration-dependent manner. The amplitude of myometrial contractions were significantly increased by NPPB and 9-AC beginning from the concentration of 10(-6)M. The frequency of myometrial contractions were significantly decreased by NPPB and 9-AC beginning from the concentration of 10(-6)M. Zaprinast inhibited the amplitude and frequency of ET-1-induced myometrial contractions in a concentration-dependent manner. Zaprinast-induced decreases in amplitude and frequency of myometrial contractions reached statistical significance beginning from the concentrations of 10(-7)M and 10(-5)M, respectively. CONCLUSION These data provide evidence that the ET-1-induced contractions of pregnant rat myometrial strips may be modulated by chloride channels. In addition, zaprinast effectively inhibited ET-1-induced contractions in pregnant rat myometrium.