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Male New Zealand White Rabbits (male + new_zealand_white_rabbits)
Selected AbstractsThe effect of tamsulosin on the response of the rabbit bladder to partial outlet obstructionNEUROUROLOGY AND URODYNAMICS, Issue 1 2006Robert M. Levin Abstract Aim To determine if tamsulosin treatment prevents or decreases the incidence and severity of outlet obstruction-induced bladder dysfunction in rabbits. Materials and Methods Male New Zealand White rabbits were treated with tamsulosin or vehicle for 4 weeks with treatments initiated 1 week prior to sham or obstruction surgery. Cystometry was done on anesthetized rabbits 21 days after surgery. The bladders were then removed, weighed, and prepared for in vitro whole bladder studies. Responses to 32 Hz field stimulation (FS), carbachol, phenylephrine, and KCl were measured. Results Obstruction resulted in a significant increase in bladder weight, which was unchanged by tamsulosin treatment and a significant increase in micturition pressure in the vehicle-treated group but not in the tamsulosin-treated group. Compliance was significantly decreased in both obstructed groups. The vehicle-treated obstructed rabbits had a very sharp increase in intravesical pressure as the bladder reached capacity; this was not seen in the tamsulosin-treated obstructed rabbits. Tamsulosin did not change the pattern of modifications in contractile responses induced by bladder outlet obstruction. Conclusions In vitro responses of vehicle and tamsulosin-treated obstructed rabbit groups in this study were similar. A greater micturition pressure was found for the vehicle-treated obstructed group than for the tamsulosin-treated obstructed group, which was probably due to decreased urethral resistance in the latter. On a functional basis, the higher compliance at capacity and decreased micturition pressure in the tamsulosin-treated obstructed group would be considered beneficial for bladder function. Neurourol. Urodynam. © 2005 Wiley-Liss, Inc. [source] Hydrogen,potassium ATPase inhibitors induce relaxation on rabbit prostatic strips in vitroINTERNATIONAL JOURNAL OF UROLOGY, Issue 11 2002Ihsan Bagcivan Summary Background : To determine the relaxant effect of omeprazole and lansaprazole, hydrogen,potassium (H+,K+) ATPase inhibitors, on rabbit prostatic tissue in vitro. Methods : Male New Zealand white rabbits were sacrificed and their prostatic tissues were removed. The prostatic stromal strips were mounted in organ baths and relaxation responses were obtained in precontracted tissues with phenylephrine, carbachol and potassium chloride (KCl). Relaxation responses were controlled in the presence of various antagonists to explain the mechanism for relaxation exerted by omeprazole and lansaprazole. Results : Omeprazole and lansaprazole caused similar relaxation responses in the prostatic strips precontracted with phenylephrine, carbachol and KCl. The addition of prostaglandin synthase inhibitor indomethacin, nitric oxide synthase inhibitor L-NAME, potassium channel blockers, glibenclamide and tetraethylammonium into the organ baths did not change the relaxations induced by omeprazole and lansaprazole in vitro. Conclusion : Omeprazole and lansaprazole cause a relaxation in prostatic stromal tissue precontracted with phenyephrine, carbachol and KC1 in vitro. This relaxant effect is independent of H+,K+ ATPase inhibition. Additionally, cyclooxygenase and nitric oxide pathways do not contribute to this relaxant effect. Further studies are required to determine whether these drugs may have a beneficial effect in the non-operative treatment of benign prostatic hyperplasia. [source] Alteration of urothelial-mediated tone in the ischemic bladder: Role of eicosanoids,NEUROUROLOGY AND URODYNAMICS, Issue 3 2004Kazem M. Azadzoi Abstract Aims Previously we showed that ischemia alters bladder smooth muscle contractility in the rabbit. This study investigates the role of urothelium and eicosanoid-release in ischemic bladder smooth muscle instability. Materials and Methods Male New Zealand white rabbits were divided into treated (n,=,12) and age-matched control (n,=,10) groups. The treated group underwent balloon endothelial injury of the iliac arteries, and then received 4 weeks of cholesterol diet, followed by 4 weeks of regular diet. The control group received a regular diet for 8 weeks. After 8 weeks, blood flow for both the iliac arteries and the bladder as well as bladder oxygen tension were recorded. In one-half of each ischemic and control bladder, the urothelium was removed. Bladder tissues were processed for organ bath and enzyme-immunoassay (EIA) of prostaglandins (PGs) and leukotrienes (LTs). Results A significant decrease in iliac arterial blood flow, bladder wall blood flow, and bladder oxygen tension was found in the treated group. Bladder ischemia increased the frequency and amplitude of baseline spontaneous smooth muscle contractility. Ischemic tissues with urothelium (Uro+) demonstrated significant increases in the contractile response to electrical field stimulation (EFS) and carbachol relative to control Uro+ tissues. Urothelial removal increased smooth muscle contraction in the control tissues but had no significant effect in the ischemic/hypoxic tissues. Contraction of control tissues without urothelium (Uro,) was similar to contraction of ischemic Uro+ tissues. Contractions of ischemic Uro+ and control Uro, tissues were unchanged after treatment with the cyclooxygenase (COX) inhibitor indomethacin, while they were significantly reduced by the 5-lipoxygenase (5-LO) inhibitor NDGA. EIA showed no change in PGs release from the ischemic urothelium, but significant increase in PGF2-, and thromboxane A2 release from the ischemic suburothelial tissue. Ischemia increased the release of LTB4, LTC4, and LTE4 from both urothelium and suburothelial tissue. Conclusions Our studies suggest loss of urothelial-mediated tone and LTs-mediated smooth muscle instability in the chronically ischemic/hypoxic bladder. Neurourol. Urodynam. 23:258,264, 2004. Published 2004 Wiley-Liss, Inc. [source] Spontaneous Ca2+ Waves in Rabbit Corpus Cavernosum: Modulation by Nitric Oxide and cGMPTHE JOURNAL OF SEXUAL MEDICINE, Issue 4 2009Gerard P. Sergeant PhD ABSTRACT Introduction., Detumescent tone and subsequent relaxation by nitric oxide (NO) are essential processes that determine the erectile state of the penis. Despite this, the mechanisms involved are incompletely understood. It is often assumed that the tone is associated with a sustained high cytosolic Ca2+ level in the corpus cavernosum smooth muscle cells, however, an alternative possibility is that oscillatory Ca2+ signals regulate tone, and erection occurs as a result of inhibition of Ca2+ oscillations by NO. Aims., The aim of this study is to determine if smooth muscle cells displayed spontaneous Ca2+ oscillations and, if so, whether these were regulated by NO. Methods., Male New Zealand white rabbits were euthanized and smooth muscle cells were isolated by enzymatic dispersal for confocal imaging of intracellular Ca2+ (using fluo-4AM) and patch clamp recording of spontaneous membrane currents. Thin tissue slices were also loaded with fluo-4AM for live imaging of Ca2+. Main Outcome Measure., Cytosolic Ca2+ was measured in isolated smooth muscle cells and tissue slices. Results., Isolated rabbit corpus cavernosum smooth muscle cells developed spontaneous Ca2+ waves that spread at a mean velocity of 65 µm/s. Dual voltage clamp/confocal recordings revealed that each of the Ca2+ waves was associated with an inward current typical of the Ca2+ -activated Cl - currents developed by these cells. The waves depended on an intact sarcoplasmic reticulum Ca2+ store, as they were blocked by cyclopiazonic acid (Calbiochem, San Diego, CA, USA) and agents that interfere with ryanodine receptors and IP3 -mediated Ca2+ release. The waves were also inhibited by an NO donor (diethylamine NO; Tocris Bioscience, Bristol, Avon, UK), 3-(5-hydroxymethyl-2-furyl)-1-benzyl indazole (YC-1) (Alexis Biochemicals, Bingham, Notts, UK), 8-bromo-cyclic guanosine mono-phosphate (Tocris), and sildenafil (Viagra, Pfizer, Sandwich, Kent, UK). Regular Ca2+ oscillations were also observed in whole tissue slices where they were clearly seen to precede contraction. This activity was also markedly inhibited by sildenafil, suggesting that it was under NO regulation. Conclusions., These results provide a new basis for understanding detumescent tone in the corpus cavernosum and its inhibition by NO. Sergeant GP, Craven M, Hollywood MA, McHale NG, and Thornbury KD. Spontaneous Ca2+ waves in rabbit corpus cavernosum: Modulation by nitric oxide and cGMP. J Sex Med **;**:**,**. [source] Evaluation of nano-technology-modified zirconia oral implants: a study in rabbitsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 7 2009Jaebum Lee Abstract Objective: The objective of this study was to screen candidate nano-technology-modified, micro-structured zirconia implant surfaces relative to local bone formation and osseointegration. Materials and Methods: Proprietary nano-technology surface-modified (calcium phosphate: CaP) micro-structured zirconia implants (A and C), control micro-structured zirconia implants (ZiUniteÔ), and titanium porous oxide implants (TiUniteÔ) were implanted into the femoral condyle in 40 adult male New Zealand White rabbits. Each animal received one implant in each hind leg; thus, 20 animals received A and C implants and 20 animals received ZiUniteÔ and TiUniteÔ implants in contralateral hind legs. Ten animals/group were euthanized at weeks 3 and 6 when biopsies of the implant sites were processed for histometric analysis using digital photomicrographs produced using backscatter scanning electron microscopy. Results: The TiUniteÔ surface demonstrated significantly greater bone,implant contact (BIC) (77.6±2.6%) compared with the A (64.6±3.6%) and C (62.2±3.1%) surfaces at 3 weeks (p<0.05). Numerical differences between ZiUniteÔ (70.5±3.1%) and A and C surfaces did not reach statistical significance (p>0.05). Similarly, there were non-significant differences between the TiUniteÔ and the ZiUniteÔ surfaces (p>0.05). At 6 weeks, there were no significant differences in BIC between the TiUniteÔ (67.1±4.2%), ZiUniteÔ (69.7±5.7%), A (68.6±1.9%), and C (64.5±4.1%) surfaces (p>0.05). Conclusion: TiUniteÔ and ZiUniteÔ implant surfaces exhibit high levels of osseointegration that, in this model, confirm their advanced osteoconductive properties. Addition of CaP nano-technology to the ZiUniteÔ surface does not enhance the already advanced osteoconductivity displayed by the TiUniteÔ and ZiUniteÔ implant surfaces. [source] Effects of testosterone and vitamin E on the antioxidant system in rabbit testisANDROLOGIA, Issue 5 2004N. Aydilek Summary. The aim of the study was to investigate the effects of testosterone propionate and vitamin E on the antioxidant system in the testis. Thirty-two male New Zealand White rabbits were randomly divided into four groups. The first group was used as control. The second group was injected with testosterone propionate, the third group vitamin E and the fourth group vitamin E and testosterone propionate combination. All treatments were carried out during 6 weeks and oxidative parameters were evaluated in homogenized testicular tissue. The levels of vitamin E and the activity of glutathione peroxidase were lower (P < 0.05) in the testosterone group than in controls. However, vitamin C and malondialdehyde levels were higher (P < 0.05) in this group than in controls. The levels of reduced glutathione, , -carotene, vitamin C and E increased, but malondialdehyde levels decreased in the vitamin E group, when compared with controls (P < 0.05). Vitamin E and , -carotene levels were significantly higher (P < 0.05) in the combination group than in testosterone group. However, MDA levels were lower (P < 0.05) in combination group than in the testosterone group. In conclusion, administration of testosterone propionate led to a significant elevation of oxidative stress. Vitamin E is quite an effective antioxidant which protects rabbit testis against lipid peroxidation, and, testosterone-induced lipid peroxidation could be improved by additional vitamin E treatment. [source] Potentiation of E-4031-induced torsade de pointes by HMR1556 or ATX-II is not predicted by action potential short-term variability or triangulationBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2007G Michael Background and purpose: Torsade de pointes (TdP) can be induced by a reduction in cardiac repolarizing capacity. The aim of this study was to assess whether IKs blockade or enhancement of INa could potentiate TdP induced by IKr blockade and to investigate whether short-term variability (STV) or triangulation of action potentials preceded TdP. Experimental approach: Experiments were performed in open-chest, pentobarbital-anaesthetized, ,1 -adrenoceptor-stimulated, male New Zealand White rabbits, which received three consecutive i.v. infusions of either the IKr blocker E-4031 (1, 3 and 10 nmol kg,1 min,1), the IKs blocker HMR1556 (25, 75 and 250 nmol kg,1 min,1) or E-4031 and HMR1556 combined. In a second study rabbits received either the same doses of E-4031, the INa enhancer, ATX-II (0.4, 1.2 and 4.0 nmol kg,1) or both of these drugs. ECGs and epicardial monophasic action potentials were recorded. Key results: HMR1556 alone did not cause TdP but increased E-4031-induced TdP from 25 to 80%. ATX-II alone caused TdP in 38% of rabbits, as did E-4031; 75% of rabbits receiving both drugs had TdP. QT intervals were prolonged by all drugs but the extent of QT prolongation was not related to the occurrence of TdP. No changes in STV were detected and triangulation was only increased after TdP occurred. Conclusions and implications: Giving modulators of ion channels in combination substantially increased TdP but, in this model, neither STV nor triangulation of action potentials could predict TdP. British Journal of Pharmacology (2007) 152, 1215,1227; doi:10.1038/sj.bjp.0707513; published online 29 October 2007 [source] Collar-induced elevation of mRNA and functional activity of 5-HT1B receptor in the rabbit carotid arteryBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2000Inge S Geerts Hypersensitivity to serotonin (5-HT) develops in rabbit collared carotid arteries. Previous data demonstrated the involvement of 5-HT1 -like receptors which are not active in normal carotid arteries. This study investigated the interaction in the rabbit carotid artery between 5-HT and a moderate tone as this can uncover functional 5-HT1 -like receptors. Furthermore, the expression of messenger RNA (mRNA) and protein of 5-HT1B, 5-HT1D and 5-HT2A receptors was addressed. Silicone collars were placed around the carotid arteries of male New Zealand White rabbits for 1 week. Rings from inside (=collar) and outside (=sham) the collar were either mounted in isolated organ baths for isometric force measurements or frozen in liquid nitrogen to isolate total RNA or proteins which were subsequently analysed by respectively reverse transcriptase-polymerase chain reaction and Western blot analysis. In sham and collared rings concentration-response curves (CRC's) to 5-HT were monophasic. Only in collared segments the presence of a 5-HT2A antagonist (spiperone or ketanserin, 0.1 ,M) revealed a biphasic CRC which was even more pronounced when a moderate tone was induced by KCl pointing to functional 5-HT1 -like receptors. The rabbit carotid artery constitutively expressed 5-HT1B and 5-HT2A mRNA, not 5-HT1D mRNA. Manipulation of the carotid artery increased the 5-HT1B mRNA level. Collar placement raised it even further. The 5-HT2A mRNA level remained unchanged. All the anti-5-HT receptor antibodies tested resulted in variable, non specific patterns with multiple bands. In conclusion, collar placement elevates mRNA expression and activity of the 5-HT1B receptor in the rabbit carotid artery. British Journal of Pharmacology (2000) 131, 1723,1731; doi:10.1038/sj.bjp.0703732 [source] Healing of rabbit calvarial bone defects using biphasic calcium phosphate ceramics made of submicron-sized grains with a hierarchical pore structureCLINICAL ORAL IMPLANTS RESEARCH, Issue 3 2010Jin-Woo Park Abstract Objectives: This study investigated the efficacy of new bone graft substitutes , biphasic calcium phosphates (BCP) made of submicron-sized grains with fully interconnected wide-range micron-scale pores in two different macrodesigns: donut shaped with a 300,400 ,m central macropore (n-BCP-1) or rod-shaped (n-BCP-2) , in the healing of rabbit calvarial defects, and compared their bone-healing properties with those of various commercial bone substitutes, which included substitutes with similar BCP composition (MBCP and Osteon), anorganic bovine bone (Bio-Oss), and ,-TCP (Cerasorb). Material and methods: The surface morphology of the bone substitutes was investigated using scanning electron microscopy (SEM). Defects 8 mm in diameter were created in the calvaria of 30 adult male New Zealand White rabbits and were filled with six types of bone substitutes. The percentage of newly formed bone (NB%) was evaluated histomorphometrically 4 and 8 weeks after implantation. Results: SEM observation showed submicron-sized grains with fully interconnected micropore structures in the n-BCP-1 and n-BCP-2 groups; these groups also showed considerable new bone formation in inner micropores as well as on the outer surfaces. The n-BCP-1 group exhibited enhanced new bone formation and direct ingrowth of bone tissue with blood vessels into central pores. Histomorphometric analysis showed significantly greater NB% in the n-BCP-1 group when compared with the other groups at 4 and 8 weeks (P<0.05). Conclusion: A new BCP ceramics made of submicron-sized grains with a hierarchical pore structure was an effective osteoconductive material for the treatment of osseous defects of rabbit calvaria. To cite this article: Park J-W, Kim E-S, Jang J-H, Suh J-Y, Park K-B, Hanawa T. Healing of rabbit calvarial bone defects using biphasic calcium phosphate ceramics made of submicron-sized grains with a hierarchical pore structure. Clin. Oral Impl. Res. 21, 2010; 268,276. doi: 10.1111/j.1600-0501.2009.01846.x [source] Significance of determining the point of reperfusion failure in experimental torsion of testisINTERNATIONAL JOURNAL OF UROLOGY, Issue 1 2005ELIJAH O KEHINDE Abstract Background:, Experimental studies of the use of free radical scavengers in ischemic/reperfusion (I/R) injury following detorsion of the torted testis have yielded conflicting results due to differences in the period of ischemia used. The authors studied I/R injury in the rabbit model, to define the point beyond which there is reperfusion failure. Methods:, Ischemia/reperfusion injury of the testis was created in 3,6-month-old male New Zealand white rabbits by cross-clamping the left spermatic cord for periods of ischemia lasting 0, 15, 30, 60, 90, 120 and 180 min. There were eight animals per experimental group. The right testis served as internal control. Both testes were harvested after 24 h of reperfusion in four animals and after 3 months in the remaining four animals for each group. Testicular malondialdehyde (MDA), a measure of free radical damage, was determined by using the thiobarbituric acid reaction on testicular homogenates. Johnsen score was used to assess morphological damage caused by the ischemia. Results:, After 24 h of reperfusion, the mean testicular MDA in the control right testes at 0, 15, 30, 60, 90, 120 and 180 min was 2.1, 2.5, 2.9, 2.4, 2.1 and 1.9 nmol/mg protein, respectively. The mean left testicular MDA at corresponding ischemic periods was 1.6, 2.0, 3.9, 10.0, 4.4, 6.1 and 1.0 nmol/mg protein, respectively. The maximum left testicular MDA was at 60 min (10.0 nmol/mg protein), following which the level dropped significantly to 1.0 nmol/mg protein at 180 min. At 3 months, the mean Johnsen scores for left testes subjected to 0, 60, 120 and 180 min ischemia were 9.4, 8.8, 2.3, 3.5, respectively. Conclusion:, The results suggest that following ischemia of up to 60 min in the rabbit testis, adequate reperfusion is possible, but ischemia lasting beyond 60 min results in inadequate reperfusion leading to irreversible damage. Thus, in experiments for assessing the effect of antioxidants on I/R injury of the testis in rabbits, periods up to 60 min of ischemia should be regarded as optimum to observe an effect. [source] Effects of xenon on ischemic spinal cord injury in rabbits: a comparison with propofolACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2010Y. YAMAMOTO Background: Xenon has been shown to reduce cellular injury after cerebral ischemia. However, the neuroprotective effects of xenon on ischemic spinal cord are unknown. The authors compared the effects of xenon and propofol on spinal cord injury following spinal cord ischemia in rabbits. Methods: Thirty-two male New Zealand white rabbits were randomly assigned to one of three groups. In the xenon and propofol group, 70% of xenon and 0.8 mg/kg/min of propofol were administered 30 min before an aortic occlusion and maintained until the end of the procedure. The aortic occlusion was performed for 15 min. In the sham group, the aorta was not occluded. After an assessment of the hind limb motor function using the Tarlov score (0=paraplegia, 4=normal) at 48 h after reperfusion, gray and white matter injuries were evaluated based on the number of normal neurons in the anterior spinal cord and the percentage areas of vacuolation in the white matter, respectively. Results: In the xenon and propofol groups, the Tarlov score and the number of normal neurons were significantly lower than those in the sham group, whereas the percentage areas of vacuolation were similar among the three groups. There were no significant differences in Tarlov scores and the number of normal neurons between the xenon and the propofol groups. Conclusion: The results indicated that 70% of xenon has no additional neuroprotective effects on ischemic spinal cord injury in rabbits compared with propofol. [source] Effects of some pharmacological agents on the survival of unipedicled venous flaps: an experimental studyMICROSURGERY, Issue 8 2001Ibrahim Askar M.D. Clinical and experimental studies have been conducted to improve the survival of venous flaps. As a result of these studies, although various survival mechanisms were raised, none obtained satisfactory information. Venous stasis, and the resultant venous thrombosis, is a factor that decreases the survival of venous flaps. In this study, we evaluated the effects of two antiinflammatory agents, etodolac and etofenamate, on the survival of unipedicled venous flaps. In this study, 35 male New Zealand white rabbits (3,500,4,000 g) (70 ears) were used. Perichondrocutaneous flaps, 3 × 4.5 cm in size, were designed and raised, keeping the central veins intact in the middle of venous flap. Central arteries and nerves were ligated and transected both proximally and distally, to prepare unipedicled venous flaps. A silicone sheet was placed between the cartilage tissue and flap, to prevent blood flow and revascularization beneath. The subjects were divided into seven groups, consisting of five rabbits (10 ears). In the negative control group (group I), the single vascular pedicle of venous flaps, central veins were ligated and flaps sutured into their own place as the composite graft. In the positive control group (group II), after venous flaps were prepared, normal saline, 0.2 mL, was given subcutaneously. In the first of five experimental groups (group III), unfractionated heparin (100 U/day) was given subcutaneously. In the second experimental group (group IV), etodolac (5 mg/kg/day) was given subcutaneously. In the third experimental group (group V), etophenamate (5 mg/kg/day) was given orally through a feeding tube. In the fourth experimental group (group VI), parnaparin (5 anti-Xa U/kg/day) was given subcutaneously. In the fifth experimental group (group VII), nadroparin (5 anti-Xa U/kg/day) was given subcutaneously, about 7 days postoperatively. At the eighth postoperative day, surviving areas of venous flaps were measured, and the results were evaluated by Kruskal-Wallis ANOVA and Mann-Whitney U-test (P < 0.05). Biopsies were also taken from the flaps for histological evaluation of border of necrotic tissue. Surviving areas of unipedicled venous flaps were larger in experimental groups than those in negative and positive control group (P < 0.05). However, comparison of the experimental groups demonstrated no statistically significant difference (P > 0.05). We concluded that all pharmacological agents used in the experimental groups succeeded in increasing the survival of unipedicled venous flaps. Survival of the unipedicled venous flap was higher in venous flaps than that of composite graft, clearly showing the importance of the venous pedicle. © 2001 Wiley-Liss Inc. MICROSURGERY 21:350--356, 2001 [source] | ||||||||||