Changes in ureteral peristaltic activity induced by various stimuli

Purinergic signalling in the urinary tract in health and disease

Purinergic signalling is involved in a number of physiological and pathophysiological activities in the lower urinary tract. In the bladder of laboratory animals there is parasympathetic excitatory cotransmission with the purinergic and cholinergic components being approximately equal, acting via P2X1 and muscarinic receptors, respectively. Purinergic mechanosensory transduction occurs where ATP, released from urothelial cells during distension of bladder and ureter, acts on P2X3 and P2X2/3 receptors on suburothelial sensory nerves to initiate the voiding reflex, via low threshold fibres, and nociception, via high threshold fibres. In human bladder the purinergic component of parasympathetic cotransmission is less than 3 %, but in pathological conditions, such as interstitial cystitis, obstructed and neuropathic bladder, the purinergic component is increased to 40 %. Other pathological conditions of the bladder have been shown to involve purinoceptor-mediated activities, including multiple sclerosis, ischaemia, diabetes, cancer and bacterial infections. In the ureter, P2X7 receptors have been implicated in inflammation and fibrosis. Purinergic therapeutic strategies are being explored that hopefully will be developed and bring benefit and relief to many patients with urinary tract disorders.

EFFECTS OF CHOLINERGIC DRUGS ON URETERAL FUNCTION IN ANESTHETIZED DOGS

PURPOSE

We evaluated the effects of the nonselective muscarinic receptor agonist carbachol (CCh) and its antagonist atropine on ureteral function in anesthetized dogs.

MATERIALS AND METHODS

Drug effects were evaluated on elevated pressure in a completely obstructed ureter and peristalsis in its partially obstructed fellow ureters as well as on intravesical isovolumetric pressure.

RESULTS

CCh (0.1 to 1.0 microg/kg intravenously) dose dependently decreased elevated pressure and peristalsis in completely and partially obstructed ureters, respectively, and increased intravesical isovolumetric pressure. On the other hand, atropine (0.1 to 1.0 mg/kg intravenously) had no significant effects on these 3 variables. Prior administration of atropine (1.0 mg/kg intravenously) completely inhibited the described CCh induced effects.

CONCLUSIONS

Our results demonstrate that in anesthetized dogs cholinergic receptor stimulation has a suppressive effect on ureteral pressure and peristalsis in obstructed ureters, in contrast to its activation of bladder smooth muscle.

Detection of missing vesicoureteral reflux with bethanechol chloride-aided voiding cystourethrography

Experience in the detection of absent vesicoureteral reflux with bethanechol-aided voiding cystourethrography is presented. The detection rate with conventional contrast-enhanced voiding cystourethrography among 9 study subjects, in whom vesicoureteral reflux otherwise was highly suspected from accompanying clinical, urographic and endoscopic features, and in whom it was absent contralaterally or bilaterally, was improved from 33 per cent (only 3 of 9 patients were positive for reflux) to 100 per cent (all 9 were proved to have vesicoureteral reflux) after bethanechol stimulation. Some representative cases are presented and the mechanisms of inducing vesicoureteral reflux with bethanechol are discussed as well as its clinical relevance. Bethanechol-aided voiding cystourethrography is suggested as a highly sensitive method to detect absent vesicoureteral reflux.