Browsing by Author "Gök Ş."

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    Possible contribution of leukotrienes in the arrhythmogenic effects of digoxin on isolated guinea-pig hearts
    (1998) Gök Ş.; Ülker S.; Evinç A.
    The effect of a leukotriene D4 (LTD4) receptor antagonist, L-648,051, was investigated in digoxin-induced cardiac toxicity in isolated guinea-pig hearts (Langendorff preparation). Digoxin infusion (25 μg.ml-1, 0.5 ml.min-1) increased perfusion pressure and contractile force initially, but decreased them later. The onset of first ventricular premature beats (VPBs) matched the increase phase, but the decrease phase was accompanied by ventricular tachycardia (VT) and fibrillation (VF). In the presence of L-648,051 (5 μmol.l-1), the initial phase was similar to that observed with digoxin alone, but the marked reduction was inhibited. This drug increased the concentration of digoxin required for VBSs and cardiac arrest, but it could not prevent the formation of VT and VF. The duration of VT was significantly decreased by L-648,051. It is concluded that the leukotriene receptor antagonist might have beneficial effects on digoxin-induced arrhythmias. Whether this effect depends on direct or indirect actions is uncertain.
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    Rate-dependent effects of dofetilide on epicardial monophasic action potentials in isolated rabbit heart with atrial pacing
    (2002) Özbek M.; Gök Ş.
    Dofetilide (UK 68,798), a new antiarrhythmic agent, blocks potassium channels selectively and acts primarily by prolonging repolarization duration. The aim of this study was to investigate rate-dependent repolarization changes due to dofetilide in a fast beating in-vitro heart model. The study was designed using Langendorff perfusion of rabbit hearts at the drug concentrations of 1 nM, 3 nM and 10 nM. The electrophysiological evaluations were performed using the recording of epicardial monophasic action potentials. Atrial pacing was set at the cycle length (ms) of 300, 325, 350, 375 and 400 so that repolarization duration could be measured in different heart rates, The study also focused on the interventricular repolarization heterogeneity between the right and left epicardial regions. Dofetilide prolonged monophasic action potential duration at 90 % of repolarization on both sides of the epicardium in a concentration- and reverse-rate-dependent manner. However, the rate-dependent prolongation of action potential duration due to dofetilide was not accompanied by increased interventricular dispersion of repolarization. No proarrhythmia due to dofetilide was seen in our model. This may be explained by the rate-dependent stability in repolarization dispersion. Thus, the presented model indicated that dofetilide-induced prolongation of repolarization is not proarrhythmic in isolated fast beating hearts.
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    The effect of nicotine among active, passive smoker health personnel; [Saǧlik çalişanlarinda, aktif ve pasif sigara i̇çicilerde nikotin etkilenim düzeyleri]
    (2009) Temel O.; Coşkun A.Ş.; Gök Ş.; Çelik P.; Yorgancioǧlu A.
    Objective: It is aimed to evaluate the effect of environmental tobacco smoke among active and passive smoker and non-smoker health staff. Material and Method: 209 volunteers were included; age, gender, occupation and smoking habits were recorded. Exhaled air carbon monoxide (CO), urinary cotinine levels and Fagerström Nicotine Tolerance Questionnaire were performed. Results: 106 (55%) of 117 active, 66 (32%) passive smokers and 26 (13%) non-smokers were male and the mean age was 30.3 ± 6.6 (18-55). 56 (27%), 33 (16%), 80 (38%), and 40 (19%) were doctors, nurses, assistant staff and officers respectively. Mean CO level was higher in active smokers (18 ppm) than passive smokers (1.9 ppm) and non-smokers (1.5 ppm) (p=0.001). Mean urinary cotinine level was higher in active smokers (949.5 ng/ml), than passive smokers (11.3 ng/ml) and non-smokers (0.00 ng/ml) (p=0.000). Nicotine consumption in active smokers was positively and significantly related with CO, urine cotinine levels and nicotine dependency (<0.05). Conclusion: It is concluded that environmental tobacco smoke has been found to be very high in hospitals and smoke-free hospital programs should ibe started immediately.
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    Glutamate mGlu5 receptor antagonist, MPEP, reduces the quinpirole-induced compulsive-like checking in rats
    (Elsevier B.V., 2017) Gök Ş.; Murat Demet M.; Öztürk Z.
    There is increasing evidence for an interaction between dopaminergic and glutamatergic systems in obsessive-compulsive disorder (OCD). In the present study, it was tested whether group I metabotropic glutamate 5 receptors (mGlu5R) mediate compulsive-like checking behavior in an animal OCD model induced by quinpirole, a dopamine D2/3 receptor agonist. Rats were tested on a large open field with four boxes placed in different locations. To induce locomotor sensitization, rats were administered quinpirole chronically (0,5 mg kg-1, twice a week for 5 weeks, sc). In the treated group, 2-methyl-6-(phenyl ethynyl) pyridine (MPEP), an mGluR5 antagonist was administered to rats (1 or 5 mg kg−1, i.p.) prior to each quinpirole injection. The distance traveled and the speed of rats were used to assess locomotor activity. After each rat's checking place was identified, the number of visits and the length of check were used as the main criteria to assess the compulsive checking behavior. The results showed that treatment of MPEP significantly inhibited the increase in QNP-induced increase in locomotion and compulsive control behavior. Our findings, therefore, support the hypothesis that mGluR5 receptors mediate dopaminergic compulsive-like control behavior. © 2017