Effect of phosphodiesterase type 4 inhibitor rolipram on cyclophosphamide-induced cystitis in rats

PubMedID: 18358472Cyclophosphamide induces a severe haemorrhagic cystitis characterized by bladder overactivity. The study was conducted to examine effects of a phosphodiesterase 4 (PDE4) inhibitor rolipram on bladder overactivity in rats with cyclophosphamide treatment. 42 female Wistar rats were used. 30 rats received a single i.p. injection of cyclophosphamide, and after 72 h, bladder function was evaluated by (1) in vitro preparations of whole bladders and (2) cystometry with continuous saline infusion under urethane anesthesia. Cyclophosphamide-treatment dramatically potentiated the basal spontaneous contractions of isolated whole bladders compared to control rats. Atropine, guanethidine or suramin was ineffective on the spontaneous contractions whereas nifedipine completely abolished. Rolipram (5-80 u{ogonek}M) induced a significant concentration-dependent decrease on the amplitude, frequency (contractions/min) and area under the curve of spontaneous contractions. Carbachol elicited phasic contractions superimposed on a tonic contraction. Rolipram caused a relaxation on the tonic contraction whereas it could not affect the phasic contractions induced by carbachol. In anesthetized rats, during continuous infusion cystometry, intercontraction interval was significantly shorter in cyclophosphamide-injected rats than in control rats. Rolipram at 5-40 µM has no significant effect on the intercontraction interval and contraction pressure while it significantly decreased pressure threshold. At 80 µM, it significantly decreased the intercontraction interval and contraction pressure. In conclusion, PDE4 inhibitor rolipram caused a significant decrease on the amplitude, frequency and area under the curve of basal spontaneous contractions in cyclophosphamide-treated rats, at doses that have no effect on the carbachol-induced phasic contractions and cystometric parameters. PDE4 inhibitors may be considered as an attractive strategy for the treatment of cyclophosphamide-induced bladder overactivity. © 2008 Elsevier B.V. All rights reserved

The effect of sub-chronic systemic ethanol treatment on corpus cavernosal smooth muscle contraction: The contribution of RhoA/Rho-kinase

PubMedID: 26728616The aim of this study was to evaluate whether the sub-chronic systemic ethanol exposure has direct effect on cavernosal smooth muscle contractions induced by KCl (depolarizing) and phenylephrine (?1-receptor agonist), and the possible involvement of RhoA/Rho-kinase pathway. Sub-chronic systemic ethanol was applied to mice with inhalation route for 14 days. The blood levels in ethanol-treated mice averaged 121.2 ± 9.1 mg/dl. KCl (80 mM) and phenylephrine (10 nM-100 µM) induced sustained contractions in corpus corporal strips from sham-treated mice. Sub-chronic ethanol treatment reduced the contractions to KCl. However, phenylephrine-induced contractions were not affected by ethanol treatment. Rho-kinase inhibitor fasudil (50 µM) and Y-27632 (50 µM) inhibited contractions to KCl and phenylephrine in sham-treated mice. Ethanol treatment increased the inhibitory effect of Rho-kinase inhibitors on contractions to phenylephrine. The relaxations induced by fasudil (100 µM) and Y-27632 (500 µM) did not change in ethanol treatment group. In ethanol-treated group, the expression of RhoA decreased compared to sham-treated group. Also, ROCK1 expression was reduced by ethanol but not statically significant to sham-treated group; however, the expression of ROCK2 increased in ethanol group. From these findings, it seems that phenylephrine and KCl-induced contractions depends on RhoA/Rho-kinase-mediated Ca2+ sensitization. Also, these results suggest that the ethanol treatment decreased the expression of RhoA, and the inhibitory effect of ethanol on KCl-induced contractions may be due to, at least in part, the inhibition of a RhoA/Rho-kinase in mouse corpus cavernosum. © 2016 Springer-Verlag Berlin Heidelberg

Neocuproine, a copper (I) chelator, potentiates purinergic component of vas deferens contractions elicited by electrical field stimulation

PubMedID: 16020948Effects of the specific copper (I) chelator, neocuproine, on the purinergic and adrenergic components of nerve-evoked contractions were investigated in the prostatic rat vas deferens. Electrical field stimulation (EFS; 4 Hz) induced bimodal contractions of vas deferens tissue in the presence of ?1-adrenoceptor antagonist prazosin (to isolate the purinergic component) or purinoceptor antagonist suramin (to isolate the adrenergic component). Neocuproine significantly potentiated the purinergic component of the contractile responses to EFS. However, the same agent failed to elicit any significant effect on the adrenergic component of nerve-evoked contractions. The copper (II) chelator cuprizone could not affect the purinergic component of contractions. The potentiating effect of neocuproine which was reversible after washout of the drug, did not occur following the application of the pre-prepared neocuproine-copper (I) complex. A nitric oxide synthase inhibitor, L-nitroarginine; a cyclooxygenase inhibitor, indomethacin or an ?2-adrenoceptor antagonist, yohimbine, failed to alter the responses to neocuproine on the purinergic component of the contraction to EFS. Neocuproine did not elicit any significant effect on preparations in which the purinergic receptors were desensitized with ?,ß-methylene ATP. In conclusion, our results suggest that neocuproine potentiates the purinergic component of rat vas deferens contractions elicited by EFS, presumably by facilitating purinergic neurotransmission and that copper (I)-sensitive mechanisms can modulate purinergic transmission in this tissue. Copyright © 2005 S. Karger AG

Differential effect of neocuproine, a copper(I) chelator, on contractile activity in isolated ovariectomized non-pregnant rat, pregnant rat and pregnant human uterus

PubMedID: 19248249The study was conducted to examine effects of a selective copper(I) chelator, neocuproine on the spontaneous or oxytocin-induced contractions in isolated ovariectomized non-pregnant rat, pregnant rat and pregnant human uterus. Uterus activity was evaluated in tissues obtained from bilaterally ovariectomized non-pregnant rats on the 21st day of the operation (n = 24), pregnant rats on the 19-21st day of gestation (n = 24) and women undergoing caesarean section at 38-42 weeks of pregnancy (n = 15). Neocuproine (100 µM) significantly suppressed the amplitude and frequency of the spontaneous contractions in the ovariectomized non-pregnant rat uterus while this agent facilitated the frequency of the spontaneous or oxytocin-induced contractions in the pregnant rat and human uterus without altering the amplitude of these contractions. At high concentration of 200 µM, neocuproine could enhance the amplitude of the contractions in the pregnant uterus. These effects were blocked by a purinergic receptor antagonist, suramin (100 µM) and did not occur following the administration of neocuproine-copper(I) complex or copper(II) chelator cuprizone. ?,ß-methylene ATP increased the amplitude and frequency of contractions in the pregnant uterus, but not affected the contractions in the ovariectomized non-pregnant rat uterus, and neocuproine potentiated this facilitation effect. However, the suppressive effect of neocuproine on the ovariectomized non-pregnant rat uterus increased in the presence of ?,ß-methylene ATP. ß-adrenoceptor blocker, propranolol or nitric oxide synthase inhibitor, l-nitroarginine did not affect the responses to neocuproine. These findings suggest that neocuproine can affect the uterus contractile activity by modulation purinergic excitatory responses and that copper(I)-sensitive mechanisms may play a role in this effect. © 2008 Elsevier B.V. All rights reserved.TF 2005 BAP15The authors wish to thank Ahmet Kantur and Zeynep Akıllı from the same department for their technical assistance. The authors are indebted to Çukurova University Experimental Research Center (TIPDAM) for the supply of rats. This work was supported by the Çukurova University Research Foundation (TF 2005 BAP15)

Residual NO modulates contractile responses and membrane potential in isolated rat mesenteric arteries

PubMedID: 29031734Shear stress or vasocontriction causes endothelial nitric oxide (NO) release resulting in the regulation of vascular smooth muscle tone in small resistance arteries. Generation of NO is inhibited by nitric oxide synthase (NOS) inhibitors. In this study, we investigated the effect of residual NO, released even in the presence of NOS inhibitors, on the membrane depolarization and phenylephrine-induced contractions of smooth muscle. For this purpose, we used hydroxocobalamin (HC), an NO scavenger, in the presence of NOS inhibitiors, N?-nitro- L-arginine (L-NA) or N?-nitro-L-arginine methyl ester (L-NAME) in mesenteric arteries isolated from rats. Phenylephrine (0,01–10 µM), an ?1-adrenoceptor agonist, led to depolarisation and concentration-dependent contraction in mesenteric arteries. The depolarisation and contractile responses were augmented by L-NA or L-NAME. Hydroxocobalamine (HC) or carboxy-PTIO (c-PTIO) also caused to further increase the membrane depolarization and contractions induced by phenylephrine in the presence of NOS inhibitors. Chemical removal of endothelium by saponin, tyrosin kinase inhibitor erbstatin A, but not calmodulin inhibitor calmidazolium inhibited the additional membrane depolarisation and contractile responses induced by L-NA or L-NAME and L-NA or L-NAME plus HC. These findings show that residual NO modulates the contractile responses in isolated rat mesenteric arteries by exerting a tonic inhibitor effect on the depolarization and vasoconstriction induced by phenylephrine. © 2017 Elsevier Inc.TF 2009BAP49This study was supported by the Çukurova University Research Foundation ( TF 2009BAP49 ). The authors wish to thank Ahmet Kantur and Zeynep Akıllı for their technical assistance. We are also indebted to Çukurova University Experimental Research Center (DETAUM) for supply of the rats

Dose-dependent differential mechanism of quercetin-induced vasodilatations in isolated perfused rat mesenteric vascular bed

Epidemiological studies indicate that low incidence of cardiovascular disease is associated with dietary intake of polyphenolic compounds, which are abundantly present in fruits and vegetables. There is solid evidence that quercetin, a polyphenolic compound, exerts vasodilator effects in addition to its antioxidant activity. Therefore, in this study, the contribution of shear stress-induced nitric oxide to the vasodilator effect of quercetin in mesenteric bed was investigated. Dose-dependent vasodilator effects of quercetin on the perfusion pressure increased by phenylephrine were recorded in the presence of L-arginine/cGMP pathway inhibitors or superoxide dismutase in the perfused mesenteric vascular beds isolated from rats. Quercetin (1, 5 and 10 µM) concentration-dependently decreased the perfusion pressure raised by phenylephrine (3-6 µM) in the endothelium-intact mesenteric bed. The relaxations occured at 1 and 5 µM quercetin were significantly inhibited by nitric oxide synthase inhibitor, N?-nitro-L-arginine (L-NA,100 µM) or the guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 5 µM), while relaxations to 10 µM quercetin were not affected. Removal of endothelium significantly reduced the relaxations at lower concentrations of quercetin but was without effect on relaxations induced by 10 µM. Calmidazolium (0.5 µM), a calmodulin inhibitor did not significantly affect the quercetin responses but a superoxide anion scavanger, superoxide dismutase (SOD, 100 U mL-1) significantly improved the quercetin-induced relaxations especially at 1 and 5 µM. These findings suggest that quercetin induces endothelium-dependent vasodilatations at lower concentrations by increasing the bioactivity of sustained nitric oxide release evoked by perfusion pressure. However, the vasodilatations induced by high concentrations of quercetin are endothelium-independent. © 2016 Ozlem Yorulmaz Ozü et al

Effects of melatonin on impaired neurogenic and endothelial relaxations by bacterial lipopolysaccharide in the mouse corpus cavernosum

PubMedID: 15161994We investigated whether bacterial lipopolysaccharide treatment causes any neuronal and vascular hyporeactivity in mouse cavernous tissue and also whether melatonin has any restorative effect on this possible neuronal and vascular hyporesponsiveness. Lipopolysaccharide treatment attenuated contractions in response to phenylephrine. Treatment with the inducible nitric oxide synthase inhibitor aminoguanidine or melatonin restored the hypocontractility of the cavernous smooth muscle to phenylephrine. Relaxant responses of corpus cavernosum precontracted by phenylephrine to acetylcholine or electrical field stimulation were significantly impaired in mice treated with bacterial lipopolysaccharide. Treatment with aminoguanidine or melatonin could prevent the impairment of the neuronal and endothelial relaxations. There was no significant difference between control and lipopolysaccharide-treated groups in the contractile response to high-dose KCl and in the relaxant response to papaverine. In conclusion, bacterial lipopolysaccharide treatment caused a neuronal and endothelial dysfunction in the mouse corpus cavernosum. A possible increased oxidative activity in the cavernous tissue may be a major reason for the impairment of relaxant responses and hypocontracility of tissue. The restorative effects of melatonin on this hyporeactivity may depend on its antioxidant properties and partly on its inhibitory action on the inducible nitric oxide synthase production. Copyright © 2004 S. Karger AG, Basel

Restorative effects of zinc and selenium on nitrergic relaxations impaired by cadmium in the mouse corpus cavernosum

PubMedID: 10643867We investigated whether Cd2+ intake (in drinking water, 15 ppm) for 30 days can affect the nitrergic relaxations of the mouse corpus cavernosum (CC) and whether Zn2+ (25 mg kg-1 via a stomach tube at 48-h intervals) or sodium selenate (8 µg kg-1 day-1 intraperitoneally) has a restorative action on the impairment in the response. Relaxant responses of the CC obtained from Cd2+-treated mice to electrical field stimulation (neurogenic) or acetylcholine (endothelium dependent) were significantly inhibited. A partial restoration was observed in the nitrergic relaxation of the CC obtained from Zn2+- or sodium selenate-co-treated animals. Neither agent exhibited any significant action on the responses of the tissue from control mice. There was no significant difference between Cd2+-treated and control mice in respect of the relaxation amplitude induced by sodium nitroprusside or papaverine. These results suggest that Cd2+ intake may impair the nitrergic relaxation of the mouse CC, and, co-treatment with Zn2+ or sodium selenate may partially improve the nitrergic mechanisms in the tissue

Effects of vitamin e and sodium selenate on impaired contractile activity by bacterial lipopolysaccharide in the rat vas deferens

PubMedID: 19330319We investigated whether bacterial lipopolysaccharide (LPS) treatment causes any hyporeactivity in rat vas deferens tissue and also whether vitamin E or sodium selenate has any restorative effect on this possible hyporesponsiveness. LPS treatment attenuated contractions to electrical field stimulation (EFS), phenylephrine, or ATP at the prostatic and epididymal ends. Treatment with the inducible nitric oxide synthase (iNOS) inhibitor aminoguanidine or vitamin E could prevent the impairment in contractile responses of both ends to EFS and phenylephrine but sodium selenate could restore these impaired contractions at only the epididymal end. LPS treatment also caused a similar significantly impairment on purinergic or adrenergic component of nerve-evoked contractions in the presence of prazosin or suramin, respectively, and vitamin E or sodium selenate could restored this impairment at both ends. On the other hand, both antioxidant agents failed to restore the impaired ATP-induced contractions in LPS-treated rats at both ends. In conclusion, LPS-treatment caused a hyporeactivity in the rat vas deferens. A possible increased oxidative activity in the vas deferens may be a major reason for the impairment of contractile responses. The restorative effects of vitamin E and/or sodium selenate on this hypocontractility may depend on their antioxidant properties or their inhibitory action on the iNOS. © 2009 Springer-Verlag.Acknowledgments The authors wish to thank Ahmet Kantur and Zeynep Akıllı from the same department for their technical assistance. The authors are indebted to Çukurova University Experimental Research Center (TIBDAM) for the supply of rats. This work was supported by the Çukurova University Research Foundation