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      The effect of nitric oxide on the pressure of the acutely obstructed ureter

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          Abstract

          Acute ureteral obstruction leads to changes in pressure inside the ureter, interrupting ureter function. The aim of our study is to explore the relationship between nitric oxide (NO) concentration and pressure in the ureter and to observe the effects of nitric oxide on the revival of renal function. We created the animal models by embedding balloons in the lower ureters of anesthetized dogs and expanding them to simulate acute ureteral obstruction. First, the test animals were pre-treated intravenously with different doses of L-NAME (non-selective nitric oxide synthase inhibitor) to inhibit nitric oxide synthase (NOS), and 10 min later, each subject was administered an intravenous dose of isoproterenol (10 μg/kg). We measured ureter pressure (UP), total and peak concentrations of NO (using an NO monitor, model inNO-T) in ureteral urine, and the volume of the urine (UFV) leaking from the balloon edge. After a certain amount of time had elapsed, it became clear that the dose of L-NAME was inversely related to the total and peak concentrations of NO, the rate of change in UP, and the volume of urine produced. We conclude that L-NAME prevents the NOS from inhibiting the release of NO, then inhibits the effect of isoproterenol reducing the pressure of the acute obstructive ureter. Inversely, we think that NO can reduce the pressure of the acute obstructive ureter and make the obstructive ureter recanalization. And when more the concentration of nitric oxide, the more the pressure will be reduced, and more urine will be collected.

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          Most cited references10

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          The obligatory role of endothelial cells in the relaxation of arterial smooth muscle by acetylcholine.

          Despite its very potent vasodilating action in vivo, acetylcholine (ACh) does not always produce relaxation of isolated preparations of blood vessels in vitro. For example, in the helical strip of the rabbit descending thoracic aorta, the only reported response to ACh has been graded contractions, occurring at concentrations above 0.1 muM and mediated by muscarinic receptors. Recently, we observed that in a ring preparation from the rabbit thoracic aorta, ACh produced marked relaxation at concentrations lower than those required to produce contraction (confirming an earlier report by Jelliffe). In investigating this apparent discrepancy, we discovered that the loss of relaxation of ACh in the case of the strip was the result of unintentional rubbing of its intimal surface against foreign surfaces during its preparation. If care was taken to avoid rubbing of the intimal surface during preparation, the tissue, whether ring, transverse strip or helical strip, always exhibited relaxation to ACh, and the possibility was considered that rubbing of the intimal surface had removed endothelial cells. We demonstrate here that relaxation of isolated preparations of rabbit thoracic aorta and other blood vessels by ACh requires the presence of endothelial cells, and that ACh, acting on muscarinic receptors of these cells, stimulates release of a substance(s) that causes relaxation of the vascular smooth muscle. We propose that this may be one of the principal mechanisms for ACh-induced vasodilation in vivo. Preliminary reports on some aspects of the work have been reported elsewhere.
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            Relationship between renal blood flow and ureteral pressure during 18 hours of total unilateral uretheral occlusion. Implications for changing sites of increased renal resistance.

            Continuous monitoring of ipsilateral renal blood flow and ureteral pressure during 18 hr of complete unilateral ureteral occlusion in five awake dogs defined the onset of preglomerular vasoconstriction, characteristic of chronic ureteral occlusion. There was a triphasic relationship between ipsilateral renal blood flow and ureteral pressure during the 18 hr of acute ureteral occlusion: (i) 0 to 1 1/2 hr, renal blood flow and ureteral pressure rose; (ii) 1 1/2 to 5 hr, renal blood flow fell while ureteral pressure continued rising; (iii) 5 to 18 hr, renal blood flow and ureteral pressure fell together. These relationships suggest different pathophysiologic mechanisms changing renal vascular resistance during the first 18 hr of complete ureteral occlusion, with increased preglomerular resistance occurring after 5 hr and being dominant in chronic ureteral occlusion.
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              Nitric oxide synthase activity in the human urogenital tract.

              Nitric oxide (NO) has been suggested as a nonadrenergic non-cholinergic neurotransmitter in the urogenital tract and has previously been shown to have a smooth muscle relaxing effect in the urogenital organs both in various animals and in humans. It has been shown that NO is a mediator of the erection and the dilatation of the bladder neck and urethra. The aim of the study was to analyse nitric oxide synthase (NOS) activity in the human urogenital tract. NOS activity was measured by the conversion of L-[U-14C] arginine to L-[U-14C] citrulline. In the upper urinary tract there was Ca(2+)-dependent NOS activity in the renal pelvis, but no significant NOS activity could be found in the ureter. In the lower urinary tract we found high Ca(2+)-dependent NOS activity in the urethra, intermediate activity in the bladder neck and comparatively low activity in the detrusor muscle. In the male genital tract the testis and epididymis had no significant NOS activity. The vas deferens, prostate, seminal vesicle and corpus cavernosum were found to have high levels of Ca(2+)-dependent NOS activity. Ca(2+)-independent NOS activity was not obtained in the urogenital tract. Our results correspond well with previous functional studies indicating NO to be an important nerve-induced mediator of erection and in the micturition reflex, but also suggest that NO may be involved in several other functions in the human urogenital tract.
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                Author and article information

                Contributors
                annan1125@sina.com
                Journal
                Urol Res
                Urological Research
                Springer-Verlag (Berlin/Heidelberg )
                0300-5623
                1434-0879
                22 June 2011
                22 June 2011
                April 2012
                : 40
                : 2
                : 163-169
                Affiliations
                The Second Affiliated Hosipital of Fujian Medical University, Quanzhou, Fujian China
                Article
                395
                10.1007/s00240-011-0395-5
                3304052
                21695424
                79143205-7a45-4ea9-8ac5-b76fb52b23d5
                © The Author(s) 2011
                History
                : 21 June 2010
                : 2 June 2011
                Categories
                Original Paper
                Custom metadata
                © Springer-Verlag 2012

                Urology
                nitric oxide synthase,obstruction,dogs,ureter,pressure,nitric oxide
                Urology
                nitric oxide synthase, obstruction, dogs, ureter, pressure, nitric oxide

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