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Öğe Evaluation of the Vasoplegic impact of Papaverine in the rat aorta(Pakistan Medical Assoc, 2014) Yavuz, Celal; Callskan, Ahmet; Karahan, Oguz; Demirtas, Sinan; Yazici, Suleyman; Guclu, Orkut; Donmez, SonerObjective: To identify the degree of vasoplegic affinity of papaverine to rat thoracic aortas following constriction caused by adrenalin, serotonin and potassium chloride in an in-vitro model. Methods: The in vitro vasoplegic efficacy of papaverine against adrenalin (10(-5) M), serotonin (5HT) (10(-4) M), and KCI (60 mM) was assessed, using a rat aortic vasospasm model in an organ bath. First, aortic rings were constricted with a submaximal dose of vasoconstrictor agents. The samples were then incubated with papaverine (3x10(-4) M) for 20 minutes, followed by readministration of the same vasoconstrictor agents. The first vasospastic response (before papaverine incubation) and the new vasoconstrictor responses (after papaverine incubation) of the vessels were then compared. Results: The vasoplegic effect of vasoconstrictor agents in decreasing order was observed as adrenalin>KCI>5HT. This different affinity for the vasoplegic effect is considered to be a temporary impact of the drugs and the maximal inhibition of vasoconstriction was detected for the adrenalin receptor. Conclusion: The relevance of the macromolecules is responsible for the permanent efficacy of the drugs. Different degrees of vasoconstriction were also obtained after papaverine administration, which suggests that different responses can occur as a result of different stimulation of receptor modulators.Öğe Iloprost relaxes phenylephrine-precontracted rat aortic rings(E-Century Publishing Corp, 2016) Peker, Recep Oktay; Donmez, Soner; Cankara, Fatma Nihan; Dogan, Emre; Gokalp, OsmanIloprost is a prostacyclin analogue mainly used in the treatment of pulmonary hypertension. It is also effective for renal dysfunction during renal transplant and coronary artery bypass grafting surgery, but there have been few comparative experimental studies with iloprost. We aimed to compare vasorelaxant properties of iloprost, with those of diltiazem, nitroglycerin and papaverine on rat thoracic aorta following phenylephrine-induced precontraction. Thirty-two young adult female Wistar albino rats were used in the study. After isolation of thoracic aorta distal to arcus, 3 mm aortic rings were placed in an organ bath and phenylephrine (10(-6) M) was added for precontraction. Subsequently, cumulative concentrations of iloprost, nitroglycerin, diltiazem and papaverine were added to aortic rings on separate chambers and dose-response curves were recorded. The mean (+/- SD) maximal relaxation (E-max) was 27.1 +/- 2.9% for iloprost, 111.7 +/- 2.1% for nitroglycerin, 77.4 +/- 2.9% for diltiazem and 147.2 +/- 2.8% for papaverine. The half maximal effective concentration (EC50) values were 2.4 x 10(-11) molar (M) for iloprost, 5.6 x 10(-8) M for nitroglycerin, 7.0 x 10(-7) M for papaverine and 2.1 x 10(-5) M for diltiazem. There was a statistically significant difference in Emax values and EC50 values between four groups (P<0.001 and P<0.01, respectively). Although a vasorelaxant response was observed with iloprost, it was less compared to papaverine, nitroglycerin and diltiazem on the isolated rat aortic rings. Iloprost has also the lowest EC50 value which could be valuable in clinical practice.Öğe Magnesium and diltiazem relaxes phenylephrine-precontracted rat aortic rings(Oxford Univ Press, 2012) Dogan, Mustafa; Peker, Recep O.; Donmez, Soner; Gokalp, OsmanPerioperative vasospasm during cardiovascular surgery is a challenging problem. Several vasodilator agents are frequently utilized for its prevention in surgical practice. Magnesium and diltiazem both have known potential vasorelaxant effects. We planned to compare the efficacy of diltiazem and magnesium in relieving phenylephrine-precontracted rat aortic rings. Ten young adult female Wistar albino rats weighing 230-260 g were used in this study. The aortic rings in the organ bath equilibrated and reached their baseline tension. Precontraction was induced by 0.001 mmol/l phenylephrine and cumulative concentration-relaxation curves were obtained by consecutively increasing the addition of either diltiazem (10(-6)-0.1 mmol/l) or magnesium (0.1-10 mmol/l). The mean maximal relaxation responses observed by diltiazem and magnesium on separate aortic rings were 90 +/- 3 and 53 +/- 2%, respectively. The calculated EC50 of diltiazem was 0.01035 mmol/l, whereas the EC50 of magnesium was 4.064 mmol/l (P < 0.05). Both magnesium and diltiazem produced vasorelaxation on phenylephrine-precontracted rat aortic rings in this study, but the potency of diltiazem regarding the EC50 value was significantly higher than that of magnesium. Magnesium could be a candidate together with diltiazem to inhibit vasospasm on arterial grafts during coronary bypass surgery.Öğe Vasorelaxant effects of dobutamine and levosimendan on rat aorta rings(Baycinar Medical Publ-Baycinar Tibbi Yayincilik, 2015) Dogan, Emre; Peker, Recep Oktay; Yener, Ali Umit; Donmez, Soner; Gokalp, OsmanBackground: In this experimental study, the vasorelaxant effects of levosimendan and dobutamine on isolated rat thoracic aorta preparations were compared. Methods: Sixteen Wistar albino type male rats were used. The thoracic aortas were removed carefully and were transferred to petri dishes containing Krebs solution. Aortic rings of approximately 5 mm in length were prepared and placed in the organ bath. Contraction and relaxation forces of the aortic rings were recorded. Contraction response was obtained by applying 10(-5)M phenylephrine to aortic rings. Subsequently, cumulative doses of levosimendan (10(-8)M-10(-4)M) was applied to eight aortic rings and cumulative doses of dobutamine (10(-8)M-10(-3)M) was applied to the other eight aortic rings and dose-response curves were recorded. The EC50 and pD2 values were calculated by the computer program named Graph Pad Prisim 4.0. The Mann-Whitney U-test was performed for statistical analysis. Results: The relaxation response of the aortic rings with levosimendan 10(-4)M administration was %92.33 while the relaxation response with dobutamine 10-4M administration was %82.48. It did not show a significant difference between both relaxation responses (p=0.059). The EC50 value was calculated as 6.605x10(-6)M for dobutamine and 5.093x10(-5)M for levosimendan. The pD2 value was found to be 5.2 +/- 0.4 for levosimendan and 4.3 +/- 0.2 for dobutamine. Conclusion: Levosimendan and dobutamine molecules in vitro rat aortic rings have similar vasorelaxant effects.
