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

1. Previous studies have established a marked difference in sensitivity to organic calcium channel blockers of the phasic compared with tonic component of the contraction to potassium chloride (KCl) in the guinea-pig ureter. The mechanisms responsible for this difference have remained unsettled. In particular, the possible involvement of non-L-type calcium channels in contractility of the ureter has not been determined. In this study we have re-addressed this problem and, to eliminate any possible contribution of sensory neuropeptides released by KCl from peripheral endings of afferent nerves, all experiments were performed in ureters pre-exposed to the sensory neurone blocking agent, capsaicin (10 microM for 15 min). 2. Increasing concentrations of KCl (10-160 mM) produced phasic and tonic contractions of the guinea-pig isolated ureter: the L-type calcium channel agonist, Bay K 8644 (1 microM), enhanced both components of the contraction to KCl. 3. Nifedipine (1 microM) abolished all responses to increasing concentrations of KCl after 60 min contact time; after a shorter incubation period (15 min), the phasic contractions to low KCl concentrations were still observed, while the tonic responses were abolished. 4. The effects of nifedipine (0.1 nM-1 microM) on the phasic and tonic components of the response to 80 nM KCl were assessed after 15-120 min contact time. Nifedipine was equipotent in inhibiting the tonic response at all times tested, while a marked time-dependency of inhibition toward phasic responses was observed. After 15 min contact time, nifedipine was 181 times more potent in inhibiting tonic than phasic response to KCl, while after 120 min contact time the difference between EC50 values was only 5.4 times. 5. Cadmium chloride (3-30 microM) was equi-effective in inhibiting the phasic and tonic responses to KCl while nickel chloride was ineffective at 10-fold higher concentrations. omega-Conotoxin (0.1 microM) and tetrodotoxin (0.3 microM) were ineffective. 6. The present findings indicate that L-type voltage-dependent calcium channels mediate both phasic and tonic components of the response of the guinea-pig ureter to KCl while neither T-type nor N-type voltage-dependent calcium channels are involved. The marked time-dependency of inhibitory action of nifedipine suggests that L-type voltage-dependent calcium channels which are responsible for the generation of phasic contraction of the ureter are in a low affinity state for interaction with nifedipine.
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PMID:A pharmacological analysis of calcium channels involved in phasic and tonic responses of the guinea-pig ureter to high potassium. 753 37

Ureteral obstruction caused by extrinsic compression by a malignancy generally can be overcome initially with a ureteral stent. However, the long-term failure rate is high, usually necessitating placement of a nephrostomy tube. Herein, we present the initial case, in this country, of intractable ureteral obstruction managed successfully with the newly developed all-metal Resonance stent (Cook Ireland Ltd., Limerick, Ireland) constructed of MP35N alloy, a composite of nonmagnetic nickel-cobalt-chromium-molybdenum. The patient is a 64-year-old woman with metastatic breast cancer causing retroperitoneal fibrosis and ureteral obstruction diagnosed laparoscopically. The obstruction failed to respond to placement of a single 7F double-J stent and then of two 6F double-J stents in the left ureter. As a last resort, in order to avoid nephrostomy-tube placement, the 6F metal stent was placed; this provided unobstructed flow of urine, as documented on a subsequent Whitaker test and, most recently, on a renal scan, 4 months after initial stent placement.
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PMID:Initial experience with full-length metal stent to relieve malignant ureteral obstruction. 1840 84

A previously healthy 30-year-old man with a symptomatic varicocele underwent gonadal vein embolization using nickel vascular plugs. He developed a painful hypersensitivity to his nickel plugs and elected to pursue laparoscopic excision and proximal gonadal vein ligation. In the operating room, the gonadal vein was isolated from the ureter, and ligated proximal to the cephalad plug and distal to the caudal coil. His pain is completely resolved 5 months after surgery. Metal allergies are well documented in orthopedics and cardiology implants, but there are a limited number of case reports of metal allergies after varicocele embolization. Interestingly, nickel is the most common type of metal hypersensitivity.
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PMID:Surgical solution to an intracorporeal nickel allergy. 2930 45