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

The spontaneous activity of guinea-pig renal pelvis-ureter is regulated by the adrenergic system. Spontaneous rhythmic contractions, and contractions induced by Noradrenaline are inhibited by Dihidroergotamine and Phentolamine. Alpha-adrenergic blocking agents block also contractions induced by histamine, angiotensin and barium chloride, but not contractions induced by electric stimulation. The Authors suggest an hypothetical model for the activation of the adrenergic receptor: Noradrenaline (NE) recognition sites are activated only by NE, whereas complementary sites can be activated by NE or other agonists. Both sites are blocked by alpha-adrenergic blocking agents.
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PMID:[Sympathetic mediation of induced and spontaneous activity of the pelvis-ureter in vitro]. 4 5

To determine whether the ureter is innervated by the autonomic nervous system, isolated canine ureters were superfused with modified Tyrode solution, and force developed in response to 100-msec duration stimuli at a rate of 3 per min was monitored. Norepinephrine and phenylephrine significantly increased developed force; the latter more than the former. These increases in developed force were blocked by phentolamine, and propranolol enhanced the stimulatory effect of norepinephrine. In the presence of phentolamine, norepinephrine significantly decreased developed force. Isoproterenol significantly decreased developed force and this significant decrease in contractility was not observed in the presence of propranolol. High intensity, high frequency, short duration stimuli which in themselves were unable to excite quiescent rabbit and canine ureteral segments potentiated contractile force of segments contracting at the basal rate of 3 per min in response to long duration stimuli. When these same high intensity, high frequency, short duration stimuli were applied to ureteral segments pretreated with phentolamine, the developed force of the basally driven preparations decreased. These data suggest the presence of alpha-stimulatory and beta-inhibitory adrenergic receptors in canine and rabbit ureter and provide evidence for adrenergic tissue within the wall of the ureter that can influence contractile force.
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PMID:Adrenergic innervation of the ureter. 71 4

I have investigated the effects of autonomic drugs and prostaglandins on in vitro smooth muscle spontaneous contractions and made the quantitative analysis of autonomic receptors in the canine ureter. Ureteral muscle strip cut helically usually generated spontaneous contractions whereas those cut circularly or longitudinally did not generate spontaneous contractions. These results suggest the importance of knowing which direction to cut the ureteral smooth muscle in order to generate spontaneous contractions. Norepinephrine (alpha), phenylephrine (alpha 1), carbachol (muscarinic) and PGF2 alpha caused significant increase in contractile force. Terbutaline (beta 2) and PGE2 caused significant decreases in contractile force, while dobutamine (beta 1) and clonidine (alpha) caused no effect. Autonomic receptor densities were determined using radiology and binding techniques. The number of maximum binding sites (Bmax) of 3H-prazosin (PZ), 3H-yohimbine (YOH), 3H-dihydroaloprenolol (DHA) and 3H-quinuclidinylbenzilate (QNB) were 53.8, 16.9, 11.2 and 5.28 fmol/ml protein, respectively. These data suggest that the contractile responses to adrenergic and cholinergic agonists in the canine ureter are mediated through functional adrenergic (alpha 1, beta 2) and muscarinic cholinergic receptors and that the prostaglandins have a role in the contraction of the canine ureter.
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PMID:[The function of autonomic receptors in canine ureteral smooth muscle]. 166 83

Electrical activity of the ureter pericystic region was found to have a definite own rhythm. Noradrenaline and adrenaline were able to induce rhythmic activity in previously inactive pericystic areas. The existence of pacemaker area in the ureter pericystic region seems to act as an additional system for coordination of polarity of the excitation-contractile waves.
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PMID:[The spontaneous activity of the perivesical area of the ureter]. 166 73

Resistance to fluid flow in the canine ureter can be divided into two categories. The higher resistance is recorded at flow rates less than or equal to 2.16 ml./min. At these rates the ureter is able to completely coapt its walls so that urine is transported in individual boluses. The lower resistance is recorded at flow rates greater than or equal to 5.40 ml./min. At these rates the ureteral walls remained open and urine is transported as a column of fluid. Noradrenaline causes a marked increase in ureteral resistance at low flow rates and a small but statistically significant increase in ureteral resistance at high flow rates. Acetylcholine increases resistance only at the low flow rates. Isoproterenol significantly decreases resistance at both low and high flow rates. These findings are consistent with ureteral resistance to fluid flow being composed of two components. One is the ureteral peristaltic contraction which plays a principal role in urinary bolus transport at low flows; the other is ureteral wall tonus, which plays an important role in the transport of columns of urine by the ureter, which does not coapt its walls, at the higher flow rates.
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PMID:Effects of noradrenaline, isoproterenol and acetylcholine on ureteral resistance. 371 89

An experimental model which permits independent changes in ureteral peristalic frequency and bolus volume was employed to explore the effects of autonomic agonists on ureteral bolus volume, peristaltic frequency, intraluminal pressure and flow volume in the dog. Norepinephrine caused an increase in ureteral peristaltic frequency, an elevation in intraureteral baseline and contractile pressure and a decrease in bolus volume, with a resultant decrease in the rate of fluid transport. Isoproterenol caused a decrease in ureteral peristaltic frequency, and a fall in intraureteral baseline and contractile pressure, or it completely abolished peristalsis and bolus formation. These changes were accompanied by an increase in the rate of fluid transport. Acetylcholine caused an increase in ureteral peristaltic frequency, an elevation of intraureteral baseline pressure but no change in contractile pressure, and a small decrease in bolus volume with a resultant small decrease in the rate of fluid transport. These data suggest that the autonomic nervous system may affect urine transport through the ureter by not only regulating peristaltic frequency but also by influencing bolus volume.
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PMID:Ureteral urine transport: changes in bolus volume, peristaltic frequency, intraluminal pressure and volume of flow resulting from autonomic drugs. 379 56

The effects of the autonomic drugs (noradrenaline, isoproterenol and acetylcholine) and the urine volume change on the pacemaker of ureteral peristalsis were studied by our new method of the in vivo recording of electromyograms (EMGs) of canine renal pelvis. The EMGs of the pelvicalyceal region showed a two phasic slow-rising potential of amplitude of 20 microV and discharge interval of 5 s and was different from propagated waves and therefore considered to be the pacemaker potentials. In the diuretic state the pacemaker potentials kept a constant discharge interval. On the contrary, the discharge interval of the ureter EMG became shorter and finally corresponded to the pacemaker EMG one to one. These results suggest that the urine transport in the diuretic state is controlled by the change of efficiency of the peristaltic propagation and not by the changes of the discharge of the pacemaker itself. Noradrenaline promoted the ureteral peristalsis and isoproterenol inhibited the ureteral peristalsis. These two drugs had no effects on the pacemaker potentials. Acetylcholine had a great variety of the effects on the ureter EMG and the pacemaker EMG separately. These results suggest that the pacemaker of the ureteral peristalsis is controlled under the influence of the parasympathetic system and the ureter is controlled under the influence of both the sympathetic and parasympathetic system.
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PMID:Effects of autonomic drugs on in vivo recording of electromyograms of canine renal pelvis and ureter. 407 49

In vivo pacemaker potentials of canine renal pelvis were able to be recorded by our new method. Potentials recorded at the pelvicalyceal region of canine renal pelvis in vivo had two phasic slow rising wave form that had duration of 0.2 sec, amplitude of 20 microV and discharge interval of about 5 sec. Furthermore, the discharge interval of ureter EMGs was a integral multiple of that of pacemaker potentials. In diuretic state by intravenous administration of furosemide, pacemaker potentials showed no change in wave form and discharge interval. However, ureter EMGs occurred more frequently to correspond to pacemaker potentials one to one. Noradrenaline and isoproterenol had no action on pacemaker potentials. To the contrary, ureter EMGs were increased by noradrenaline and were decreased by isoproterenol. Acetylcholine had a great variety of action on both pacemaker potentials and ureter EMGs. These results suggest that the pelvicalyceal region as thought to be the pacemaker of ureteral peristalsis is controlled under the influence of parasympathetic nerve system and the ureter is controlled under the influence of both sympathetic and parasympathetic nerve systems.
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PMID:[Studies on the in vivo pacemaker potentials of the canine renal pelvis]. 652 Nov 27

1. The effects of papaverine (10(-5)-2 X 10(-4) M) were studied on the evoked electrical and mechanical activity of the guinea-pig ureter smooth muscle. In normal conditions the action potential consists of an initial spike followed by further spikes superimposed on a plateau phase. Papaverine reversibly decreased the duration of the plateau of the action potential, blocked the associated spikes, greatly reduced the amplitude of the contraction but enhanced the initial component of the action potential. 2. Papaverine did not change the membrane potential and had little effect on the membrane resistance. 3. Tetraethylammonium (5 mM), which blocks the delayed outward K current, did not prevent the decrease in the duration of the plateau nor the decrease of the contractile response caused by papaverine. 4. In Na-free solution the duration of the action potential was decreased until only a single spike was seen, due to suppression of the plateau. An effect of papaverine could not be observed under these conditions. 5. Mn2+ ions (1 mM) completely suppressed the spike component and tension while the plateau component was substantially increased. Papaverine in the presence of Mn2+ reversibly blocked the generation of the action potential. When Mn2+ ions were added to Na-free solution the duration as well as the amplitude of the spike was increased. Again, papaverine reversibly blocked the generation of the action potential. 6. Noradrenaline (10(-4) M) and histamine (10(-5) M) in normal conditions prolonged the duration of the action potential plateau and increased both the duration and amplitude of the concentration. Papaverine again blocked the plateau and greatly reduced the contractile response. 7. Papaverine caused the relaxation of KCl-induced contractures, preferentially blocking the tonic component. 8. It is suggested that the inhibitory action of papaverine on ureter smooth muscle results from its specific blockade of the 'slow' Na/Ca channels responsible for the generation of the plateau component of the action potential.
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PMID:The effects of papaverine on the electrical and mechanical activity of the guinea-pig ureter. 686 69

The conduction velocity of peristaltic movements of the canine ureter was measured under anaesthesia with a new type of diameter gauge using an image sensor. The peristaltic velocity was 34.1 +/- 6.2 mm/sec in 10 experiments. Noradrenaline at a low dosage of 1 microgram/kg i.v. reduced the resting diameter, increased the conduction velocity to 47--56 mm/sec, and approximately doubled the frequency of contraction. The application of acetylcholine also caused an increase in both frequency and conduction velocity (42--46 mm/sec). A plot of the conduction velocity against the mean period of peristaltic contraction was hyperbolic in shape.
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PMID:Conduction velocity of peristaltic waves in the in vivo ureter: application of a new diameter gauge. 723 14


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