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Öğe Cooling and response to hydrogen peroxide in human saphenous vein: role of the endothelium(WILEY, 2005) Sahin, AS; Atalik, KE; Sahin, TK; Dogan, NIn the present work we studied the responses of human saphenous vein to H2O2 and effects of moderate cooling on these responses with analysis of the role of endothelium. H2O2 (10(-7)-10(-2) m) induced concentration-dependent contraction in the intact human saphenous vein strips at both temperatures. At 28 degrees C, the maximal contraction induced by H2O2 was significantly lower than that at 37 degrees C. Compared with intact strips, the sensitivity and the maximal contraction to H2O2 were significantly enhanced in endothelium-denuded strips at 37 and 28 degrees C. However, pD(2) values and maximal contractions were not significantly different in endothelium-denuded strips at different temperatures. Pretreatment with N-G-nitro-L-arginine methyl ester (L-NAME) increased significantly the maximal contraction and sensitivity to H2O2 at 37 and 28 degrees C. The contractions increased by L-NAME were restored by the pre-incubation Of L-arginine (10(-3) m) at every temperature studied. The contractile responses of intact human saphenous veins to H2O2 were reduced significantly by 10(-5) m indomethacin at both temperatures. Our results suggest that H2O2-induced contraction of human saphenous vein are mediated by its direct effect on the smooth muscle and by the generation of products of the cyclooxygenase pathway from the endothelium. Signalling pathways of these contractile effects are the same at 3 7 and 28 degrees C. Under normal temperature conditions, the contraction to H2O2 is possibly modulated by endothelial nitric oxide. Cooling reduces the contraction to H2O2 by increasing release of nitric oxide.Öğe The in vitro effects of remifentanil and fentanyl on isolated human right atria and saphenous veins(W B SAUNDERS CO, 2003) Duman, A; Sahin, AS; Atalik, KE; Ogun, C; Ulusoy, HB; Durgut, K; Okesli, SObjective: To determine the myocardial and vascular effects of remifentanil and fentanyl in human atria and saphenous veins. Design: In vitro, prospective with repeated measures. Setting: University research laboratory. Interventions: The direct effects of remifentanil and fentanyl on the electrical stimulation-induced contraction of nonfailing human atrium and saphenous veins contracted with 5-hydroxytryptamine were studied. Measurements and Main Results: In human atrial trabeculae, cumulative (10(-9)-10(-5) mol/L) added remifentanil had in 0 effect on contractile force, compared with untreated muscles (p > 0.05). The force of contraction was significantly less than control values with concentrations of fentanyl ranging from 10(-8) to 10(-5) mol/L (p < 0.05). At the highest concentration (10(-5) mol/L), the inhibition by fentanyl of the electrical stimulation-induced contraction was 40.6% +/- 6.32%. In human saphenous vein strips preconstricted with 5-hydroxytryptamine, remifentanil (10(-8)-10(-5) mol/L) and fentanyl (10(-8)-10(-5) mol/L) produced "concentration-dependent" relaxation when compared with the control contraction value (p < 0.05). The IC50 was similar with remifentanil and fentanyl and the E-max of fentanyl was significantly higher than remifentanil (p < 0.05). The venodilatory effects of remifentanil and fentanyl were similar on veins with or without endothelium (p > 0.05). Conclusions: Remifentanil has no direct effect on the contraction of myocardium. Fentanyl inhibits the electrical stimulation-induced contraction in human right atrial muscles in vitro. Remifentanil and fentanyl produce "concentration-dependent" relaxation in human saphenous vein strips independent from the endothelium. (C) 2003 Elsevier Inc. All rights reserved.Öğe Remifentanil has different effects on thoracic aorta strips in different species, in vitro(BLACKWELL MUNKSGAARD, 2004) Duman, A; Ogun, CO; Sahin, AS; Atalik, KE; Erol, A; Okesli, S[Abstract not Available]Öğe The role of K+ ions on the response to carbachol of calf coronary artery and cardiac vein during cooling(PROUS SCIENCE, SA, 2001) Atalik, KE; Sahin, AS; Ulusoy, HB; Dogan, NThe role of K+ ions on the vasoconstrictions induced by carbachol during cooling (28 degreesC) in the endothelium of a denuded calf coronary artery and cardiac vein (noncutaneous vessel) was studied. Carbachol (10(-9) - 3 X 10(-4)M) induced concentration-dependent contractions at both 37 degreesC and 28 degreesC. The sensitivity, but not the maximal response, of carbachol (10(-9) - 3 x 10(-4) M) was significantly lower at 28 degreesC than at 37 degreesC. Cooling to 28 degreesC after treatment with tetraethylammonium (TEA, 10(-3) M) or ouabain (10(-5) M), or after incubation in K+-free medium, increased the sensitivity to carbachol in both preparations. The results suggest a role for K+ ions in the cooling-induced changes of noncutaneous vessels. (C) 2001 Prous Science. All rights reserved.Öğe Warming and response to contractile agents in calf cardiac vein: Role of the Ca2+, K-Ca(2+), and Na+ ion channel blockers(PROUS SCIENCE, SAU-THOMSON REUTERS, 2005) Atalik, KE; Sahin, AS; Dogan, NThe effects of wartning (to 41 degrees C) oil the serotonin (5-HT, 10(-8)-3 x 10(-3) M)- and carbachol (10(-9)-3 x 10(-4) M)-induced contractions and the role of calcium (Ca2+). potassium (K+), and sodium (Na+) channel blockers, in the warming-induced responses were investigated in the calf cardiac vein. Concentration-response curves to 5-HT and carbachol were isometrically recorded at 37 and 41 degrees C (control). The same procedure was repeated at 41 degrees C in the presence of verapamil (10(-6) M), caffeine (3 x 10(-4) M), tetraethylammonium (TEA, 10(-3) M), flecainide (10(-6) M), and also in the Ca2+-free medium with ethlylene glycol bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA). During warning, the sensitivity, but not the maximum response, was significantly higher. Warming to 41 degrees C after treatment with verapamil or flecainide decreased the sensitivity, whereas treatment with caffine increased the sensitivity significantly. Treatment with TEA (lid not modify the effect of warming. Furthermore, warming to 41 degrees C after incubation in Ca2+-free solutions with EGTA decreased the sensitivity to 5-HT and carbachol. The results of this study suggest the role for Ca2+ and Na+ ions in the warming-induced changes of cardiac vein treated with 5-HT and carbachol. (c) 2005 Prous Science. All right reserved.Öğe Warming and Response to Contractile Agents in Calf Cardiac Vein: Role of the Nitric Oxide(BLACKWELL PUBLISHING LTD, 2003) Atalik, Kısmet Esra; Sahin, AS; Ulusoy, HB; Dogan, NThe effects of warming on the response to various contractile agents of calf cardiac vein were studied using 2.5-mm long cylindrical segments. Concentration-response curves for carbachol (10(-9)-3 x 10(-4) M), 5-hydroxytryptamine (5-HT; 10(-8)-3 x 10(-3)), potassium chloride (KCl; 10(-4)-5 x 10(-2) m) and calcium chloride (CaCl2; 10(-4)-10(-2)) were isometrically recorded at 37 and 41degreesC (warming). During warming the sensitivity, but not the maximal response, of carbachol 5-HT, KCl, and CaCl2 was significantly higher than at 37degreesC. Warming to 41degreesC after treatment with N-G-nitro-L arginine methyl esther (10(-5) m) did not modify the effect of warming. These results suggest that nitric oxide seems to have no role in the warming-induced responses in calf cardiac vein.
