Biomedical subjects

Tijen Utkan

Publications and source records attributed to Tijen Utkan.

10 recordsLinked to original sources

PubMed2006

Effect of dextromethorphan on reference memory assessed in rats by a three-panel runway task.

The effects of dextromethorphan (DM, CAS 6700-34-1), a common over-the-counter cough suppressant, on the reference memory have been investigated by a three-panel runway setup in rats. This study was designed by using a repeated acquisition procedure such as a radialarm maze task or a water maze task. DM (20-40 mg/kg i.p.) produced a significant decrease in the number of errors (pushes made on the two incorrect panels of the three panel gates at four choice points) and latency. Systemically administered scopolamine (CAS 114-49-8) (1 mg/kg i.p.) impaired the performance on both parameters. DM (40 mg/kg i.p.) was effective in reversing the reference memory deficit induced by administration of scopolamine. DM acts as a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptors. Our results suggest that inhibition of NMDA receptors by DM supports its potential positive properties. This finding might present an oppurtunity for the evaluation of this old antitussive drug.

Animals↗

PubMed2004

Foregut smooth muscle reactivity changes in the hydrocephalus-induced infantile rats.

BACKGROUND: An association between hydrocephalus and gastroesophageal motor abnormalities that cause gastroesophageal reflux (GER) is well known. Our aim was to investigate hydrocephalus-induced alterations in esophageal and gastric smooth muscle reactivity and their modulation by pharmacological interventions in the rat model. MATERIALS AND METHODS: Hydrocephalus was induced in infantile rats by injection of kaolin into the cisterna magna. Hydrocephalic and sham-operated rats were exsanguinated 2 weeks after surgery. Esophageal and gastric fundus smooth muscle strips were studied in vitro for their contractile and relaxant response to receptor activation in the organ chambers set up. Additionally, esophageal and gastric tissue specimens were examined histologically for GER-induced changes. RESULTS: No histological evidence of esophageal and gastric changes reflecting GER was observed in the specimens of the control and hydrocephalus-induced rats. Maximum contractile responses of esophageal and gastric fundus smooth muscle to KCl and muscarinic receptor agonist carbachol were increased in the hydrocephalic groups compared with the control groups. These changes were statistically significant. Relaxant responses to beta adrenoceptor agonist isoprenaline were similar in the esophageal muscle strips of both hydrocephalic groups and the control groups. However, isoprenaline-induced relaxant responses of the gastric fundus muscle strips in the hydrocephalus-induced groups were significantly decreased as compared with the control groups. The relaxant responses to papaverine in the esophageal and gastric fundus smooth muscle strips were similar in the two groups. CONCLUSIONS: Our study revealed alterations of receptor-dependent and receptor-independent foregut smooth muscle reactivity in the hydrocephalus-induced rat pups. Therefore, we suggest that impaired smooth muscle reactivity at least in part may contribute to abnormalities of foregut motor function seen in patients with hydrocephalus.

Age Factors↗

PubMed2003

Gastric smooth muscle contractility changes in the esophageal atresia rat model: an in vitro study.

PURPOSE: The aim of the study was to investigate the gastric smooth muscle reactivity in the Adriamycin-induced esophageal atresia (EA) rat model. METHODS: The fetuses were divided into 3 groups. The control group was exposed to saline. The second group was comprised of fetuses that were exposed to Adriamycin but did not have EA (Adriamycin-no-EA group). The third group was comprised of fetuses that were exposed to Adriamycin and had EA (Adriamycin-EA group). Gastric fundus strips were studied in vitro for their contractile response to receptor activation in the 3 groups. RESULTS: Contractile responses of gastric smooth muscle to carbachol and KCl were increased in the Adriamycin-EA group compared with the Adriamycin-no-EA group. Also serotonin-induced contractile response in the Adriamycin-EA group decreased compared with the Adriamycin-no-EA group. Relaxation of gastric smooth muscle strips to isoproterenol was comparably unaffected in the Adriamycin-EA and Adriamycin-no-EA groups. Likewise, no change in the response to agonist studies was observed between the control and Adriamycin-no-EA groups. The relaxant response to papaverine was not different in the 3 groups. CONCLUSIONS: This study found changes of receptor-dependent and receptor-independent contraction of the gastric fundus smooth muscle in the fetuses with EA. Therefore, impaired contractile responses may be, at least in part, a contributing factor in the abnormal gastric motility seen in EA.

Animals↗

PubMed2003

Investigation of the mechanism of nicotine-induced relaxation in guinea pig gallbladder.

BACKGROUND: Muscular contraction of the gallbladder is the primary determinant of bile delivery into duedonum. Gallbladder filling and emptying are influenced by both inhibitory and excitatory stimuli, and NO plays a key role in normal relaxation. In this study, to determine whether nicotine acts on the gallbladder muscle, the mechanism of its effect on strips of guinea pig gallbladder was studied in vitro. MATERIALS AND METHODS: Guinea pig gallbladder muscle strips were mounted in organ bath with modified Krebs-Henseleit solution and aerated with Carbogen. Tension was measured with isometric force transducers, and muscle relaxation was expressed as percent decrease of precontraction induced by carbachol. RESULTS: Nicotine produced concentration dependent relaxation when preparations were precontracted by carbachol (10(-6) M). Nicotine-induced relaxation was 51.6 +/- 3.2% of phenylephrine contraction and was not affected by guanethidine (10(-5) M), propranolol (10(-6) M), hexamethonium (10(-4) M), indomethacin (10(-5) M), N(w)-nitro L-arginine methyl ester (L-NAME) (3 x 10(-5) M), methylene blue (10(-5) M), glibenclamide (10(-5) M), clotrimazole (10(-6) M), tetraethylammonium (3 x 10(-4) M), or 4-aminopyridine (10(-3) M). Nicotine did not exhibit a calcium antagonizing effect. CONCLUSIONS: From these results, we concluded that nicotine-induced relaxation of the guinea pig gallbladder is not mediated by the release of noradrenaline, nitric oxide (NO), prostaglandins, or a related substance, or by the activation of potassium channels, or by the stimulation of nicotinic cholinoceptors. Further work is needed to determine the cellular mechanism(s) of action by which nicotine acts on gallbladder smooth muscle.

Adrenergic alpha-Agonists↗

PubMed2003

Effects of caustic lye injury to the esophageal smooth muscle reactivity: in vitro study.

PURPOSE: We investigated late effects of caustic lye injury on esophageal smooth muscle reactivity in the rat model. MATERIALS AND METHODS: Male Sprague-Dawley rats were divided into two groups. Through a median laparatomy incision, abdominal esophageal segment was isolated. Orogastric and gastric (via gastrotomy) catheters were placed and tied over the isolated esophageal segment. Saline (0.9%) or 50% sodium hydroxide (1 ml) solution were instilled via orogastric catheter to the isolated segment in the control and caustic esophagus (CE group) groups, respectively. Then, the esophagus was rinsed with 0.9% saline via gastric catheter. The esophagus was removed and studied in organ chambers 28 days after the operation. RESULTS: Carbachol- and KCl-induced contractile responses of esophageal smooth muscle were significantly reduced in the CE group with decreased E(max) value compared with the control group. Relaxant responses to serotonin were significantly reduced in the CE group with decreased E(max) value compared with the control group. No significant differences were found in E(max) and pD(2) values for papaverine acting on esophageal strips from the two groups. CONCLUSION: The results provide evidence that, a surgically created caustic injury causes impaired smooth muscle reactivity that may contribute to esophageal motor dysfunction.

Animals↗

PubMed2003

Impaired gastric motility in the gastroesophageal reflux rat model: an in vitro study.

PURPOSE: The present study investigated the effects of acid and mixed reflux on the responsiveness of gastric smooth muscle in the gastroesophageal reflux (GER) rat model. MATERIAL AND METHODS: Three groups of rat were studied encompassing acid reflux, mixed reflux and sham operation. Acid reflux was induced by pyloric ligation (AR group) and mixed reflux was induced by jejunal ligation 1 cm distal to Treitz ligament (MR group). Similar surgical manipulations were carried out in the sham operated rats (SO group). Carbachol-, serotonin-, KCl-induced contractile response and nicotine-, sodium nitroprusside-, papaverine-induced relaxant response in isolated gastric fundus smooth muscle strips were determined using in vitro muscle technique 24 h after surgery. RESULTS: Isolated gastric fundus smooth muscle contractility to serotonin, carbachol or KCl was significantly reduced in the AR and MR groups with decreased Emax and pD(2) values compared with the SO group. Relaxant responses to nicotine was significantly increased in the AR and MR groups with increased Emax and pD(2) values compared with the SO group. Sodium nitroprusside and papaverine-induced-relaxant responses were similar in all of the groups and there was no change in agonist potency. CONCLUSION: The present study indicates that decreased contractile and increased nicotine-induced relaxant response of the gastric smooth muscle in the surgically created GER model. These findings suggest that impaired gastric smooth muscle reactivity at least in part may play a role in gastric dysmotility in GER.

Animals↗

PubMed2003

Age-related smooth muscle reactivity changes in the rat bladder: an in vitro study.

An experimental study was conducted to investigate developmental changes of the rat detrusor smooth muscle (DSM) reactivity from newborn to adult period. Urinary bladders were obtained from adult (4 months old), 1-month-old and newborn (4-7 days old) male Sprague-Dawley rats. DSM reactivity of the three groups was evaluated in organ chambers. The newborn DSM strips revealed markedly increased purinoceptor- and cholinoceptor-mediated contractions (ATP, carbachol) with increased maximum response (2.98- and 8.96-fold increase for ATP, 2.90- and 4.22-fold increase for carbachol, when the newborn bladder compared with 1-month-old and adult groups, respectively) and sensitivity (1.65- and 1.29-fold increase for ATP when the newborn bladder compared with the 1-month-old and adult groups, respectively). Additionally the maximum contractile response to KCl in the bladder from the newborn was 1.65- and 8.96-fold increased compared to bladders of the 1-month-old and adult groups, respectively. However, no significant changes in the adrenoceptor-mediated relaxation (isoproterenol) of the rat DSM were observed among the groups. These results indicate that development alters the in vitro responsiveness of rat DSM. The newborn rat bladder gains some of the adult bladder properties within 1 month. These changes are likely to reflect the changing role of parasympathetic regulation in the DSM reactivity during development of the rat bladder.

Adenosine Triphosphate↗

PubMed2003

Esophagitis impairs esophageal smooth muscle reactivity in the rat model: an in vitro study.

The present study investigated how reflux-induced esophagitis affects the smooth muscle reactivity of the esophageal body. Two different esophagitis models were used: acid gastric and mixed duodenogastric reflux. All test animals apart from the controls developed gross and histologic evidence of esophagitis. Contractile (carbachol and KCI) and relaxant (isoproterenol) esophageal smooth muscle responses were significantly decreased in the presence of acid- and mixed reflux-induced esophagitis. Similar relaxant responses to serotonin and papaverine were found in the three groups. Our study demonstrated impaired esophageal smooth muscle reactivity when esophagitis was induced by acid or mixed reflux. These changes may correspond to the functional motor abnormalities of the esophagus seen in patients with reflux esophagitis.

Animals↗

PubMed2003

Inhibitory effect of harmane on morphine-dependent Guinea pig ileum.

Studies on the occurrence and properties of b-carbolines structurally related to harmala alkaloids have gained attention since it was hypothesized that some of these compounds play a role in processes of substance abuse and dependence. This study investigates the effects of harmane on naloxone-precipitated withdrawal syndrome in morphine-dependent guinea pig ileum. Segments of ilea from starved male guinea pigs were obtained and fixed at a resting tension of 1 g in an organ bath containing 10(-6) M morphine in Tyrode solution at 37 degrees C, which was bubbled with 95% O(2) and 5% CO(2). Tissues were incubated in 10(-6) M morphine containing Tyrode solution for 4 hours before harmane was added. Naloxone and harmane had no effect on naive ilea. Naloxone (10(-6) M) contracted morphine-dependent ilea. Harmane significantly inhibited the contractile response to naloxone in a dose-dependent manner (10(-7) M = 24%; 10(-6) M = 49.3%; 10(-5) = 70%). These results suggest that harmane may have beneficial effects on morphine withdrawal syndrome.

Adrenergic alpha-Antagonists↗

PubMed2002

Aging impairs nitric oxide-mediated relaxant responses of rabbit corporal smooth muscle.

Aging has been reported to cause impotence, the mechanism of which is unknown. Therefore, we investigated the effect of aging on electrical stimulation-induced neurogenic, carbachol-induced, endothelium-dependent, and sodium nitroprusside-induced cGMP-dependent relaxant responses of rabbit corporal smooth muscle. Male New Zealand white rabbits were divided into young (4 months), intermediate (8 months), and old (24 months) groups. Electrical stimulation-, carbachol-, sodium nitroprusside-, and papaverine-induced relaxant response in isolated corporal smooth muscle strips were determined using in vitro muscle technique. Although there was no significant difference in the relaxant response of corporal strips to papaverine among the groups, relaxant responses to carbachol and sodium nitroprusside were significantly lower in corporal strips of old group than both young and intermediate groups. However, in the old and intermediate groups, electrical field stimulation-induced neurogenic relaxation was significantly reduced compared with the young group. KCl-induced (124 mM) contractile responses were the same in all groups. Our data indicate that the presence of age-dependent differences in the NO/cGMP-mediated relaxant responses of corporal tissue in the male rabbits. This may contribute to the development of impotence.

Aging↗