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

The effect of nifedipine (Adalat) on isolated dog ureter was compared with that on isolated coronary artery. Nifedipine at a concentration of 10(-8) mol/l significantly decreased the frequency of ureteral rhythmic contractions evoked by potassium, and suppressed the force of these contractions at a concentration of 3 X 10(-8) mol/l. In potassium-contracted coronary artery strips, nifedipine at concentrations more than 3 X 10(-9) mol/l produced significant relaxations in a concentration-dependent manner. The results indicate that nifedipine is able to act inhibitorily on ureteral contractions, and inhibition of pace making activities in ureteral smooth muscle was suggested as a mode of action of nifedipine.
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PMID:Comparison of the effects of nifedipine on ureter and coronary artery isolated from the dog. 403 84

Partial obstruction of 1 ureter was created in newborn rats and its effects were studied in the adult rat. The obstructed renal pelvis was found to be about 6 times enlarged and the weight of the kidney was 85 per cent of the contralateral intact one. Despite considerable distortion of the inner medulla on the obstructed side, no loss of weight in this region was observed. The only changes observed with respect to tissue concentrations--which were significantly due to the obstruction--were increases in urea in the cortex (110 per cent) and in potassium in the inner medulla (21 per cent); thus, the changes were few and, in part, moderate. The findings are compared with previous observations of solute excretions and the pathophysiological implications are discussed. The conclusion is that although the inner medulla was considerably distorted, the solute content was far from being affected to a corresponding degree--at least not in this experimental preparation.
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PMID:Experimental obstructive hydronephrosis in newborn rats. V. Long-term effects on renal tissue solute content. 403 63

The effects of verapamil, a calcium antagonist agent, were studied on smooth muscle preparations of the lower urinary tract of horses. Verapamil (2 X 10(-4) to 2 X 10(-8) M) relaxed the ureter, urethra and urinary bladder preparations contracted by potassium (127 mM), L-noradrenaline (2 X 10(-5) M), histamine (2 X 10(-5) M) and acetylcholine (2 X 10(-5) M). These results allow the conclusion that verapamil has a dose-dependent relaxing effect on smooth muscle of the lower urinary tract.
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PMID:Effects of verapamil on the smooth muscle of the horse urinary tract. 408 36

1. The capacity of adaptation of toads (Bufo bufo) to environments of high salinity was studied and the relative importance of skin, kidney and urinary bladder in controlling the balance of water and salt was assessed.2. Toads were kept in NaCl solutions of 20, 50, 110, 150 and 220 mM and studied in their fourth week of adaptation. A group of animals considered as ;control' was kept in wet soil with free access to water. Plasma, ureter urine, and bladder and colon contents were analysed for sodium, potassium, chloride and osmolality, and total body sodium and water were determined. Absorption of water and (22)Na through the skin, and water flow and sodium excretion through the ureter, of intact animals was studied. Hydrosmotic water transport through the isolated urinary bladder of ;control' and adapted animals was determined. The effects of pitressin and aldosterone on the water and sodium balance are described.3. The survival rates of toads kept in saline concentrations up to 150 mM were identical to that of ;control' animals, but half of the animals kept in 220 mM died within 4 weeks.4. There is a linear correlation between the sodium concentrations and osmolality of plasma and of the external media.5. The sodium concentration in colon contents rose with rising external concentrations, up to values higher than the values in plasma.6. Sodium concentrations and osmolalities of ureter and bladder urine increased in adapted animals, the values for bladder urine becoming much higher than those for ureter urine in animals adapted to 110, 150 and 220 mM.7. Total body water, as a percentage of total weight was kept within very narrow limits, although the total body sodium increased with adaptation.8. Absorption of water through the skin for the same osmotic gradients was smaller in adapted than in ;control' animals.9. The ureteral output of water of toads adapted to 110 and 150 mM-NaCl was larger than the water absorption through the skin.10. Skin absorption of sodium was lower in animals adapted to concentrated saline solutions than in ;control' animals.11. Sodium output by the ureter was identical to skin absorption in ;control' animals adapted to 20, 50 and 110 mM-NaCl but was higher in animals adapted to 150 mM-NaCl.12. Aldosterone increased the absorption of sodium in ;control' and adapted toads, but at all dose levels absorption by control was greater than by adapted animals.13. The stimulation of water absorption by vasopressin in vivo or in isolated bladders was not modified in animals adapted to high salinities.
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PMID:Salt adaptation in Bufo bufo. 463 11

1. Acute experiments were carried out on anaesthetized dogs during metabolic alkalosis produced by I.V. administration of NaHCO(3). Partial constriction of one ureter led to a significant rise in the HCO(3) (-) threshold, beyond the simultaneous value for the other kidney. The magnitude of the increase was not correlated with the reduction of glomerular filtration.2. Stop-flow analysis, following complete unilateral obstruction of urine flow, demonstrated proximal as well as distal tubular reabsorption of bicarbonate. At any given plasma P(co2) the detailed configuration of the concentration changes which developed depended on (a) the presence and concentration of mannitol, (b) the duration of urinary stasis, and (c) the plasma concentration of HCO(3) (-).3. If a solution containing 15% (w/v) mannitol was infused I.V., the HCO(3) (-) concentration in free flow urine was lower than in plasma, and it fell further during arrest of flow in the entire column of trapped fluid. If less mannitol was infused, or none at all, interruption of urine flow led to a striking increase of HCO(3) (-) concentration in the distal portion of the occluded column, and to a fall in the fluid arrested in the proximal segments.4. It was demonstrated that the HCO(3) (-) concentration attained after 2(1/2), 6, or 15 min of urinary stasis at any point in the trapped fluid column was due to the combined effects of water reabsorption and HCO(3) (-) reabsorption which proceeded independently, and with a different time course.5. If mannitol was administered the lowest urinary HCO(3) (-) concentration in the series moved progressively to a more distal location with increasing duration of urinary stasis. When HCO(3) (-) concentration peaks were present in distal fluid they were conspicuous only after short interruptions of urine flow; during extended stop-flow periods they became attenuated, or disappeared. If no mannitol was administered this did not occur.6. Provided the plasma level of HCO(3) (-) was sufficiently elevated, mannitol (15%, w/v) was administered, and the time available for reabsorption was lengthened by ureter obstruction, much larger concentration differences between plasma and trapped fluid developed than the largest that are ever found between the plasma and freely draining urine. The magnitude of the largest plasma-urine (P-U) concentration difference for HCO(3) (-) increased with intratubular ;contact time', and no limiting value was found.7. Potassium concentration in distal occluded fluid fell with prolonged duration of stasis. This was related to the slow and progressive diminution of distal HCO(3) (-) concentration. But if instead of bicarbonate a nonreabsorbable anion, such as phosphate, was the dominant distal anion, K(+) concentration in distal fractions remained high and rose further with time.
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PMID:Factors modifying renal tubular bicarbonate reabsorption in the dog. 563 89

The metabolic fate of potassium dodecyl [(35)S]sulphate was studied in rats. Intraperitoneal and oral administration of the ester into free-ranging animals were followed by the excretion of the bulk of the radioactivity in the urine within 12hr., approximately 17% being eliminated as inorganic [(35)S]sulphate. Similar results were obtained in experiments in which potassium dodecyl [(35)S]sulphate was injected intravenously into anaesthetized rats with bile-duct and ureter cannulae. Analysis of urinary radioactivity revealed the presence of a new ester sulphate (metabolite A). This metabolite was isolated, purified and subsequently identified as the sulphate ester of 4-hydroxybutyric acid by paper, thin-layer and gas chromatography, by paper electrophoresis and by comparison of its properties with those of authentic butyric acid 4-sulphate. The identity of the metabolite was confirmed by isotope-dilution experiments. When either purified metabolite A or authentic potassium butyric acid 4[(35)S]-sulphate was administered to free-ranging rats the bulk of the radioactivity was eliminated unchanged in the urine within 12hr., approx. 20% of the dose appearing as inorganic [(35)S]sulphate. Whole-body radioautography and isolated-liver-perfusion experiments implicated the liver as the major site of metabolism of potassium dodecyl [(35)S]sulphate. It is suggested that butyric acid 4-sulphate probably arises by omega-oxidation of dodecyl sulphate to a fatty acid-like compound, which is then degraded by beta-oxidation.
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PMID:The metabolism of potassium dodecyl [35-S]sulphate in the rat. 577 48

1. A study has been made of the ionic basis of the smooth muscle membrane potential by changing the ionic environment of the ureter and recording the resultant potential changes with the sucrose gap. The relation of these potential changes to the membrane potential of individual cells has also been studied.2. It is shown that if the ionic environment of all the cells in the tissue is uniformly changed, then the potential change recorded by the sucrose gap is proportional to the magnitude of the short circuit factor, the liquid junction potential change at the sucrose-test solution interface, and the amplitude of the membrane potential change of a single cell.3. A simple method is described for determining the steady value of the short circuiting factor, and the liquid junction potential changes, so that the recorded potentials can be corrected to give membrane potentials.4. The action of isotonic potassium sulphate and isotonic potassium chloride on the membrane potentials of the ureter smooth muscle cells is described.5. When the extracellular potassium concentration is changed reciprocally with the extracellular chloride concentration in order to maintain these ions in a Donnan equilibrium across the muscle cell membrane, the membrane potential is found to decrease by 53 mV for a 10-fold change in external potassium concentration, for concentrations above 10 mM.6. It is concluded that above an external potassium concentration of 10 mM the membrane potential of ureteral smooth muscle cells obeys the prediction of the Nernst equation for a potassium electrode.
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PMID:Application of the sucrose-gap method to determine the ionic basis of the membrane potential of smooth muscle. 591 61

The effect of alpha-adrenergic and cholinergic receptor stimulation is quantitatively analyzed in different regions of the pig pyeloureter. Smooth muscle strips from minor calyces, pelvis proper and ureter were investigated. Stimulation with potassium (127 mM) was used as reference. Both phenylephrine and carbachol caused a concentration-dependent increase in basal tone in the pelvis and the minor calyx. The maximum response obtained was significantly smaller in the pelvis than in the minor calyx. As compared to phenylephrine, the response to carbachol was negligible. The ureter showed a different behavior as compared to the minor calyx and pelvis. A constant basal tone could not be obtained and the tissue did not respond to potassium in a reproducible way.
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PMID:Topographic variations in alpha-adrenergic and cholinergic response in the pig renal pelvis. 619 91

Substance P-immunoreactivity (SP-IR) in the guinea-pig ureter was found to be totally depleted after systemic capsaicin pretreatment. Removal of the inferior mesenteric ganglion (IMG) led to a total depletion of SP-IR from the rostral third of the ureter and to a partial depletion from the caudal third. Electrical stimulation of the IMG caused Evans blue extravasation mainly in the rostral third of both ureters, whereas stimulation of the right pelvic nerve caused Evans blue extravasation in the caudal third of the ureters on both sides. The responses to nerve stimulation were absent in capsaicin-pretreated animals. Furthermore, capsaicin caused release of SP-IR from ureter slices in vitro, this release was not inhibited by tetrodotoxin. Potassium (60 and 120 mM) also released SP-IR. It is concluded that SP-IR in the ureter is contained in capsaicin-sensitive sensory neurons reaching the ureter via both parasympathetic (caudal part) and sympathetic nerves (rostral part). Activation of these neurons by capsaicin leads to a peripheral release of SP-IR which most likely increases vascular permeability.
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PMID:Capsaicin-induced substance P release and sensory control of vascular permeability in the guinea-pig ureter. 619 95

In the ureter smooth muscle cells, high--K solution produced a depolarization at the onset of which the action potentials (AP) and contraction occur; the latter consists of an initial phasic (Ph) and subsequent tonic (T) components. Ph component is initiated by the AP, T component--by a stable potassium depolarization. In Ca--free solution the AP, Ph and T components are blocked, although a sustained potassium depolarization is preserved. Basing on these results it is suggested that: 1) phasic contraction is initiated by calcium ions influxed via fast potential--dependent calcium channels participating in the AP generation; 2) tonic contraction is also initiated mainly by extracellular calcium influx through slow potential--dependent calcium channels of plasmatic membrane that appear to be similar to calcium channels of sarcoplasmic reticulum membrane in skeletal muscles and of the membrane of presinaptic nerve terminals.
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PMID:[Effect of potassium ions on electrogenesis and contraction of ureter smooth muscle]. 625 70


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