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

A chronic canine model was developed to study the immediate mechanical effects of ureteral calculi. Totally implanted nephrostomy tubes were used to measure renal pelvic pressure and optical sensors recorded ureteral activity. Surrogate calculi were inserted in a retrograde fashion via a trigonal vesicostomy. Complete obstruction was more common with larger calculi and these all passed spontaneously, by which time ureteral activity had ceased. Reduction in urine output delayed the rise in renal pressure and thus prolonged the time the calculus was retained in the ureter. If large calculi, which normally obstruct, had holes drilled in them to allow free urine flow they remained in the ureter for at least 2 hours and had to be extracted. Therefore, in the first few hours increased proximal hydrostatic pressure was the most important factor responsible for the spontaneous passage of obstructing calculi.
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PMID:Experimental study of ureteral calculus disease: effects of calculus size, obstruction and hydration. 663 17

Complete obstruction of one ureter was created in 3-week-old weanling rats. The endothelin concentration in the renal tissue was measured by radioimmunoassay. In the obstructed kidney, a substantial increase was observed, after 1 week +90%, after 2 weeks +55%, and after 4 weeks +145% compared to the control rat kidneys. The endothelin-1/endothelin-3 ratio was found to be considerably raised, indicating a predominance of the vasoconstrictor effects of the--with reference to vasoactivity--bi-potential endothelin. Its contribution to vasoconstriction and to glomerular destruction in obstructive nephropathy is discussed.
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PMID:Renal tissue endothelin in long-term complete ureteric obstruction in the young rat. 780 17

The contribution of changes in ureter motility produced by a stone to the pain of ureteric calculosis is unclear. In this study we measured ureter motility as changes in intraureter pressure in anesthetized rats 1, 4, and 8 d ys after implantation of an artificial calculus (n = 33) and compared it with motility in normal (n = 8) and ligated (n = 4) ureters. Partial obstruction of the ureter by the stone produced a 478% increase in the amplitude of contractions, a 70% decrease in the rate of contractions, and a 66% decrease in the baseline pressure. The pressures reached during contractions were equivalent to those evoking nociceptive reactions in animals and humans. These changes persisted in rats that had spontaneously eliminated the stone. Complete obstruction of the ureter by the stone or by ligation abolished contractions. We conclude that the increased motility caused by a stone likely contributes to the development and maintenance of visceral pain and referred hyperalgesia in ureteric colic and to the persistence of referred hyperalgesia after elimination of the stone.
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PMID:Effects of artificial calculosis on rat ureter motility: peripheral contribution to the pain of ureteric colic. 917 31

Complete obstruction of the ureter causes atrophy of the renal parenchyma, especially marked in the portions lateral to the renal sinus. The longer the duration of the obstruction, the greater is the degree of atrophy. If the obstruction is removed within 2 weeks the kidney may regain its normal structure except for a varying amount of atrophy in the lateral portions. Kidneys obstructed for 2 weeks or less may regain their normal function, as measured by the phthalein test. The longer the period of obstruction, the slower is the rate of recovery. A hydronephrosis of 7 days' duration required 40 days, and one of 14 days' duration required 152 days to recover normal function.
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PMID:RENAL FUNCTION IN EXPERIMENTAL HYDRONEPHROSIS. 1986 50