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

In diet-induced potassium depleted rats, tissue potassium content of the renal medulla decreases and membrane-bound droplets form in the cytoplasm of medullary cells. To elucidate the interrelationship between medullary potassium concentration and intracytoplasmic droplets, ligation of the left ureter was performed on rats deprived of potassium for 2 weeks. Our results show that, even in the absence of supplemental potassium provision to the animal, a unilateral rise in tissue potassium of the ligated left kidney was significant. After 4 days of ligation, the left medullary potassium was 41.96 +/- 0.79 mEq/100 g dry weight compared to 32.51 +/- 0.84 mEq/100 g dry weight (P less than 0.001) of medullary potassium in the non-ligated right kidney. The rise in tissue potassium in the left kidney coincided with the dissolution of intracytoplasmic droplets. We conclude, that mechanical obstruction to urinary flow can dissolve storage droplets in medullary cells and that the lysis of droplets is made possible by the increase in medullary tissue potassium content.
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PMID:Effects of ureteral ligation on renal medullary lesions of potassium depletion. 631 93

Renal tubular function has been studied in pig fetuses of 105-112 d gestational age in new-born pigs 5-9 d old. The experiments were performed on anaesthetized animals, urines being collected by inserting a catheter into one ureter of the animal under study. The glomerular filtration rate was estimated and plasma concentrations and urinary excretion of the following substances were measured: sodium, potassium, calcium, ammonia, urea, phosphate, glucose fructose, creatinine, protein and exogenous 4-aminohippuric acid, and inulin. The reabsorption of water was considered in relation to the plasma vasopressin values. New-born pigs were loaded with glucose and fructose in order to determine the maximal tubular transport rate of these substances. Significant changes at birth occur in only a few functions of the tubulus system. Following delivery, major changes are: (1) the increased reabsorption of sodium and water which is probably the most important adaptation to extra-uterine life; (2) an apparent increasing impermeability of the tubular epithelium for creatinine, and (3) the direction of transport of fructose, which is reabsorbed by fetuses whereas neonates demonstrate a net secretion. Glucose and fructose are transported by different mechanisms. The experiments with fructose-loaded piglets demonstrate that there are at least two transport mechanisms for fructose: reabsorption - either passive or active - and secretion. The factors causing a shifting from one mechanism to the other are not yet known.
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PMID:Perinatal development of tubular function in the pig. 651 94

A partial obstruction of 1 ureter was created in newborn rats and its effects were studied in the adult rat. The obstructed pelvis was found to be considerably enlarged. Nevertheless, the GFR (glomerular filtration rate) was only slightly decreased (10 per cent), completely compensated by increase on the contralateral, non-obstructed side. The reduction in GFR was less than the reduction in number of glomeruli (19 per cent), indicating a raised filtration rate per glomerulus. Water excretion was slightly increased and potassium excretion moderately decreased; sodium and osmolar excretion were not significantly affected. There was no correlation between these changes and the degree of pelvic enlargement. Thus, in this model, in which there is no urinary tract infection or pyelonephritis, partial obstructive uropathy caused less damage to the kidney function than might have been expected.
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PMID:Experimental obstructive hydronephrosis in newborn rats. III. Long-term effects on renal function. 683 22

The case is reported of a young woman with severe hypertension, unilateral renal artery stenosis, variously normal or marginally high plasma concentrations of active renin, angiotensin II, aldosterone, sodium, and potassium; and normal total exchangeable and total body sodium and potassium. Arteriograms and ureter catheterization showed the stenosis to be severe, but the unstimulated renal vein renin and angiotensin II differential to be modest. Captopril caused an initial fall in angiotensin II and arterial pressure. During prolonged captopril treatment, plasma angiotensin II and aldosterone remained depressed; exchangeable and total body sodium and potassium were unaltered. Blood pressure fell further to normal levels during prolonged captopril treatment, while subsequent surgical correction of the renal artery stenosis was curative; absolute values of blood pressure and plasma angiotensin II were similar in both situations. The findings support, without proving, the concept that chronic modest elevation of angiotensin II may be responsible for sustained hypertension in unilateral renal artery stenosis. Patients of this type contrast sharply with those, also with severe renal artery stenosis or occlusion, who have gross elevation of renin, angiotensin II, and aldosterone, with sodium and potassium deficiency. Captopril or surgery are effective in both syndromes, but the manner of response to treatment differs markedly.
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PMID:Renal artery stenosis with normal angiotensin II values. Relationship between angiotensin II and body sodium and potassium on correction of hypertension by captopril and subsequent surgery. 700 27

Contractions were chemically induced in vitro in pig uterus segments by a high potassium concentration in a metabolic solution. Slow contractions were found mainly in the transverse direction. The near absence of contractions in the longitudinal direction is ascribed to a nearly circular orientation of the muscle fibers. (In terms of the helical muscle-fiber model of the ureter, our findings would correspond to a pitch of 3 to 5 degrees for the helix.) It is further postulated that the coupling structure of fibers in the transverse direction, determining an annular contraction mode, differs from that in the longitudinal direction, determining the longitudinal propagation of the annular contraction mode. The over-all conclusions on the basis of our results is that the helical muscle-fiber model now generally assumed for the ureter must be greatly modified to correlate with the experimental facts that its continued use is misleading and undesirable.
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PMID:Potassium-induced contractions in pig ureter strips. Consequences for helical muscle-fiber model of ureter. 711 98

1. A comparison was made of the metabolism of potassium D-(+)-octan 2-[35S]sulphate and potassium L-(-)-octan-2-[35S]sulphate in the rat. 2. Following administration of either enantiomer orally or i.v. the major proportion of the radioactivity was excreted in the urine within 24 h. When either enantiomer was administered i.v. to rats with bile-duct and ureter cannulae, the majority of the radioactivity was eliminated in the urine within six hours with only small amounts in bile. 3. Both enantiomers were extensively degraded in vivo. The metabolic products were identical with those previously reported (Maggs et al. 1982). 4. The major difference in the metabolite patterns was with respect to the relative amounts of hexanoate-5-sulphate: male and female urines contained approx. twice as much of this metabolite when the D-(+)-isomer was administered. In addition, isomer and sex-linked differences were observed with respect to the amounts of octanoate-7-sulphate.
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PMID:The effect of configuration of the sulphate moiety on the metabolism of potassium octan-2-sulphate in the rat. 715 31

Experiments were carried out on smooth muscle cells (SMC) of the guinea-pig ureter by the double sucrose gap method with simultaneous recording of electrical and contractile activities. The effect of histamine on SMC was studied in normal Krebs solution and in sodium-free Krebs solution with TEA. In normal Krebs solution, histamine was shown to increase the duration of AP plateau and contraction. In sodium-free Krebs solution with TEA, the APs of ureter SMC also had a plateau that was determined by the increased calcium conduction of the membrane. In these conditions, histamine provoked a decrease in the duration of the AP plateau and contraction. The histamine effect was blocked by phencarol both in normal and sodium-free Krebs solution with TEA. A possible role of sodium, calcium and potassium ions in the modulating action of histamine on excitation of ureter SMC is discussed.
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PMID:[Mechanism of modulating effect of histamine on the excitation and contraction of smooth muscles of the ureter]. 717 28

The effect of different albumin concentrations on whole kidney function has been studied in the isolated perfused rat kidney. When a dialyzer was included in the perfusion circuit, GFR and sodium transport remained nearly constant for 2 h. Perfusion flow rate was directly correlated with albumin concentration. GFR was low (0.56 ml.min-1.g-1) at high albumin concentration (7.6 g/100 ml) and highest (1.38 ml.min-1.g-1) when albumin was omitted. The latter observation differed from earlier findings by other investigators who found a reduced GFR in the absence of albumin. This reduced GFR could be explained by ureteral backpressure, which results from the use of narrow ureter catheters. Fractional sodium reabsorption was approximately 50% irrespective of load when albumin was absent, and reached 90% at a GFR of 0.95 ml.min-1.g-1 when 5-6 g/100 ml albumin was used. At reduced load, fractional sodium reabsorption approached in vivo values of 98%. Potassium secretion was observed at high urinary flow rates when albumin concentration was low; low urinary flow rates at high protein concentration were associated with net potassium reabsorption.
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PMID:Effect of albumin on the function of perfused rat kidney. 724 41

In ureter-ligated rats, the pressor effects of both norepinephrine and angiotensin II i.v. on systemic blood pressure and serum sodium concentration were significantly decreased when compared with those in control rats, while serum potassium concentration, blood urea nitrogen, mean systemic blood pressure and plasma renin activity were significantly increased. The microscopic examination of aortic smooth muscles did not show significant histological lesions in the tissues obtained from ureter-ligated rat. The responsiveness of aortic strips isolated from ureter-ligated rats to norepinephrine and angiotensin II was significantly decreased in comparison with that from control rats. The results suggest that a decreased pressor response to norepinephrine and angiotensin II under ureter-ligated conditions may be attributed to a decrease in vascular reactivity to drugs.
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PMID:Changes in vascular reactivity in rats with experimental renal insufficiency. 732 63

1. HCO3(-)-dependent mechanisms involved in the regulation of intracellular pH (pHi) were characterized using double-barrelled pH-sensitive microelectrodes in smooth muscle cells of the isolated guinea-pig ureter. 2. Removal of external Cl- in the presence of CO2-HCO3- caused a transient alkalosis, consistent with the presence of Cl(-)-HCO3- exchange, before pHi slowly recovered. Recovery from acidosis in the presence of CO2-HCO3- was not affected, at a time when intracellular Cl- would have been maximally depleted, indicating that a counter transport of Cl- and HCO3- was not involved. The recovery was also not affected by amiloride, indicating that Na(+)-H+ exchange was not involved. 3. A transient hyperpolarization was associated with the recovery from acidosis in the presence of CO2-HCO3-, consistent with rheogenic coupling of Na(+)-HCO3- cotransport. However, depolarization caused by elevation of the extracellular potassium (K+o) concentration, which should favour inward transport by the rheogenic mechanism, caused a fall in pHi and decreased the rate of recovery from acidosis. Furthermore, ouabain abolished the transient hyperpolarization without affecting the recovery of pHi. It is concluded that Na(+)-HCO3- cotransport in the ureter is electroneutral. 4. Recovery from acidosis in the presence of CO2-HCO3- was insensitive to DIDS even after prolonged pre-equilibriation and extreme acidosis. The results suggest that Na(+)-HCO3- cotransport in the ureter is insensitive to DIDS and that Cl(-)-HCO3- exchange does not reverse to contribute to the extrusion of acid equivalents. A HCO3- conductance may account for the Na(+)-independent, HCO3(-)-dependent recovery from extreme acidosis. 5. Recovery from experimentally induced alkalosis was inhibited by Cl(-)-free conditions and by DIDS, indicating that Cl(-)-HCO3- exchange was involved. 6. It is concluded that pHi in the smooth muscle of guinea-pig ureter is controlled by three transport mechanisms. By far the most important is an electroneutral Na(+)-HCO3- cotransporter. Na(+)-H+ exchange appears to play little role in the presence of the physiological buffer. Both of these mechanisms extrude acid equivalents and so protect the cell against its fairly substantial intrinsic intracellular acid loading. Cl(-)-HCO3- exchange, on the other hand, is stimulated by intracellular alkalosis to transport acid equivalents into the cell and so restore a more normal pHi.
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PMID:Regulation of intracellular pH in the smooth muscle of guinea-pig ureter: HCO3- dependence. 752 76


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