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Query: UMLS:C0403608 (ureter)
 9,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The excretion of radioisotope following the administration of three specifically 14C-labelled forms of streptozotocin was investigated in the rat using ureter and bile duct cannulation techniques. The urine collected during the first hour following the administration of the drug contained the highest proportion of injected radioactivity (approximately 34% with (3'-methyl-14C)-streptozotocin and approximately 40% each with (1-14C)-and (2'-14C)-streptozotocin. Over the entire experimental period (6 hours), approximately 70% of the injected radioactivity of (1-14C)- and (2'-14C)-streptozotocin appeared in the urine. With (3'-methyl-14C)-streptozotocin, only 53% of the injected radioactivity appeared in the urine over the same period. In contrast to the high urinary excretion, less than 3% of the injected radioactivity from all three radiolabelled streptozotocin samples appeared in the bile. The in vivo and in vitro metabolism of streptozotocin was also investigated. In addition to substantial amounts of unchanged drug, three radiolabelled metabolites (two major and one minor) were detected in the urine during the 6 hour collection period following the administration of (1-14C)- and (2'-14C)-streptozotocin. In contrast, only unchanged (3'-methyl-14C)-streptozotocin was detected in the urine collected over the same period following the administration of the methyl labelled drug. The two major metabolites were also produced when (1-14C)-and (2'-14C)-streptozotocin were incubated with a rat liver supernatant fraction (100,000 X g). The liver was further demonstrated to be the major site of metabolism in isolated liver perfusion studies in which both (1-14C)- and (2'-14C)-streptozotocin were quantitatively converted to the two major metabolites. The two major metabolites of (1-14C)-streptozotocin, whether produced in vivo or in vitro, were chromatographically homogenous with the two major metabolites formed from (2'-14C)-streptozotocin. Nicotinamide pretreatment had no apparent effect on the urinary excretion of streptozotocin and its metabolites.
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PMID:Streptozotocin: its excretion and metabolism in the rat. 13 5

ensp;The distribution and colocalisation of nicotinamide adenine dinucleotide phosphate reduced-diaphorase (NADPH-d)-/nitric oxide synthase (NOS)-containing (nitrergic) neurons in the innervation of the duck ureter have been studied using histochemistry and immunohistochemistry. Quantitative analysis showed that nitrergic neurons made up 60% and 70% of the total intramural and adventitial neuronal populations, respectively. About 40% of intramural nitrergic neurons expressed VIP-immunoreactivity, and about 75% of nitrergic adventitial neurons expressed TH-immunoreactivity. The density of nitrergic adventitial neurons was significantly greater in the lower tract than in the upper and intermediate tracts. Nerve lesioning experiments showed that the majority of ureteral nitrergic innervation was extrinsic in origin; nitrergic adventitial neurons primarily projected caudocranially, whereas NOS-immunoreactive and NOS-/VIP-immunoreactive intramural neurons primarily projected craniocaudally. These findings suggest that, in birds, the nitrergic innervation plays a role in ureteral functions such as epithelial mucosecretion, muscular motility, and the closing and/or opening of the ureteral papilla.
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PMID:The distribution and colocalisation of nicotinamide adenine dinucleotide phosphate reduced-diaphorase (NADPH-d)-/nitric oxide synthase (NOS)-containing neurons in the innervation of the duck ureter. 1100 Feb 80

This MiniReview focuses on the role played by nitric oxide (NO) and hydrogen sulfide (H2 S) in physiology of the upper and lower urinary tract. NO and H2 S, together with carbon monoxide, belong to the group of gaseous autocrine/paracrine messengers or gasotransmitters, which are employed for intra- and intercellular communication in almost all organ systems. Because they are lipid-soluble gases, gaseous transmitters are not constrained by cellular membranes, so that their storage in vesicles for later release is not possible. Gasotransmitter signals are terminated by falling concentrations upon reduction in production that are caused by reacting with cellular components (essentially reactive oxygen species and NO), binding to cellular components or diffusing away. NO and, more recently, H2 S have been identified as key mediators in neurotransmission of the urinary tract, involved in the regulation of ureteral smooth muscle activity and urinary flow ureteral resistance, as well as by playing a crucial role in the smooth muscle relaxation of bladder outlet region. Urinary bladder function is also dependent on integration of inhibitory mediators, such as NO, released from the urothelium. In the bladder base and distal ureter, the co-localization of neuronal NO synthase with substance P and calcitonin gene-related peptide in sensory nerves as well as the existence of a high nicotinamide adenine dinucleotide phosphate-diaphorase activity in dorsal root ganglion neurons also suggests the involvement of NO as a sensory neurotransmitter.
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PMID:The Role of Nitric Oxide and Hydrogen Sulfide in Urinary Tract Function. 2686 22