Characterization of .ALPHA.-adrenoceptor subtypes involved in regulation of ureteral fluid transport.

Abstract

Experiments were carried out in the dog by the use of experimental procedure which permits to assess independently changes in uretheral peristaltic frequency, bolus volume and intraluminal pressure and flow volume in order to characterize a-adrenoceptor subtypes involved in regulation of ureteral urine transport. Norepinephrine caused an increase in ureteral peristaltic fregency, an elevation in intraureteral baseline and contractile pressure and a decrease in bolus volume, with a resultant decrease in the rate of fluid transport. Phenylephrine (al-agonist) and clonidine (a2-agonist) caused the effects similar to those of norepinephrine on peristaltic frequency, intraureteral baseline and contractile pressure, and bolus volume. Phentolamine (non-selective a-antagonist) and prazosin (a,-antagonist) caused a decrease in ureteral peristaltic frequency, and a fall in intraureteral baseline and contractile pressure, and yohimbine (a2-antagonist) abolished peristalsis and bolus formation. These changes were accompanied by an increase in the rate of fluid transport. These data suggest that the ureteral urine transport is controlled by activation of both al-and a2-adrenoceptors through regulation of peristaltic frequency and bolus volume, ureteral urine transport ; a-adrenoceptor subtypes

Treatment of Ureteral Lithiasis with Tamsulosin: Literature Review and Meta-Analysis

“…Some time later, various articles on diverse clinical trials tried to provide evidence on the use of ␣ -blocking drugs as a new indication. In recent years, studies have focused on tamsulosin on the basis that it is more effective and diminishes side effects with regard to other ␣ -blocking drugs [5][6][7][8][9] .…”

“…The mechanism of action of tamsulosin includes blocking ␣ -adrenergic receptors, which are more abundant in the distal ureter zone [5] , and triggering an increase in urinary flow from the proximal ureter, since a decreased peristalsis movement raises descending pressure and diminishes pressure below the lithiasis when the ureteral [6] and bladder neck muscles relax.…”

Modification of ureteral motility and promotion of urine flow around an intraureteral obstruction by CL‐316243, phenylephrine, and furosemide in dogs

“…We also speculate that both of these e¡ects may facilitate stone passage in urolithiasis patients. Morita et al [1987] reported that phenylephrine increases ureteral peristalsis and IUP and decreases the UF through an unobstructed ureter in anesthetized dogs. In contrast to the e¡ect of CL-316243, we also observed that phenylephrine concentration dependently and greatly enhanced both the amplitude and frequency of spontaneous rhythmic contractions in the isolated canine ureter.…”

“…Intravenous administration of the a1-AR agonist phenylephrine to anesthetized dogs increases ureteral peristaltic contractions and the IUP and reduces the UF through an unobstructed ureter [Morita et al, 1987]. On the other hand, the loop diuretic furosemide increases the UF with a secondary elevation in the basal IUP in dogs [Pohl et al, 1991].…”

Evaluation of the efficiency of tamsulosin and Rowatinex in patients with distal ureteral stones: a prospective, randomized, controlled study

“…It was suggested that the blockage of alpha-1 adrenergic receptors in the ureter leads to decreased ureteral peristaltic activity with a consequent loss of interureteral pressure and an increase in fluid transport ability [5,6]. Morita et al demonstrated that selective alpha-blocking agents increase interureteral pressure gradient around the obstructed ureter by increasing the bolus of urine above the stone and decreasing the interureteral pressure below the stone [10]. This might facilitate stone passage by increased urine flow.…”