Second Prize: In-Vivo Physiological Impact of Alpha Blockade on the Porcine Ureter with Distal Ureteral Obstruction

Effects of Alpha-Blockade on Ureteral Peristalsis and Intrapelvic Pressure in an In Vivo Stented Porcine Model

INTRODUCTION

Clinical studies have shown beneficial role of oral alpha-blockers for ureteral stent-related morbidity. However, the in vivo effects of oral alpha-blockers on a stented ureter are unclear. We evaluated the effects of alpha-blockade on ureteral dynamics in a stented porcine ureter.

METHODS

Twenty-seven female pigs were used in this study. Fourteen pigs received oral alpha-blocker medication (silodosin, 8 mg daily), and 13 pigs received no medication. Under cystoscopic guidance, a 5F ureteral catheter was positioned in the renal pelvis and attached to a pressure monitor. A Foley catheter was placed in the bladder along with a bladder pressure transducer. A lumbotomy was performed, and the ureter was identified. A magnetic sensor was placed on the extraluminal surface of the ureter to monitor ureteral peristalsis. We measured renal pelvic and bladder pressures, urine output, and ureteral peristalsis every hour for 10 minutes for a total of 5 hours. The pigs were then euthanized.

RESULTS

The mean weight was 42.5 kg in the drug group and 45.9 kg in the nondrug group (p = 0.008). Mean hourly urine output was 140 mL in the drug group and 144 mL in the nondrug group (p = 0.76). Mean baseline renal pressure was 13.2 and 13.8 mm Hg (p = 0.69) in the drug and nondrug groups, respectively. Mean peristaltic renal pelvic pressure was 19.1 mm Hg in the drug group and 19.2 mm Hg in the nondrug group (p = 0.97). Mean number of peristalsis was 11/10 and 14/10 minutes (p = 0.03) in the drug and nondrug groups, respectively.

CONCLUSIONS

Alpha-blockade in an in vivo stented porcine ureter resulted in no significant effect on renal pelvic pressure but a significant decrease in the number of ureteral peristalsis. Further investigation of the effects of alpha-blocker on ureteral dynamics is required to better understand its effects on stent-related symptoms.

Effect of Flos carthami Extract and α 1-Adrenergic Antagonists on the Porcine Proximal Ureteral Peristalsis

Traditional Chinese medicine (TCM) has been proposed to prevent urolithiasis. In China, Flos carthami (FC, also known as Carthamus tinctorius) (Safflower; Chinese name: Hong Hua/紅花) has been used to treat urological diseases for centuries. We previously performed a screening and confirmed the in vivo antilithic effect of FC extract. Here, ex vivo organ bath experiment was further performed to study the effect of FC extract on the inhibition of phenylepinephrine (PE) (10⁻⁴ and 10⁻³ M) ureteral peristalsis of porcine ureters with several α₁-adrenergic antagonists (doxazosin, tamsulosin, and terazosin) as experimental controls. The results showed that doxazosin, tamsulosin, and terazosin dose (approximately 4.5 × 10⁻⁶ − 4.5 × 10⁻¹  μg/mL) dependently inhibited both 10⁻⁴ and 10⁻³ M PE-induced ureteral peristalsis. FC extract achieved 6.2% ± 10.1%, 21.8% ± 6.8%, and 24.0% ± 5.6% inhibitions of 10⁻⁴ M PE-induced peristalsis at doses of 5 × 10³, 1 × 10⁴, and 2 × 10⁴  μg/mL, respectively, since FC extract was unable to completely inhibit PE-induced ureteral peristalsis, suggesting the antilithic effect of FC extract is related to mechanisms other than modulation of ureteral peristalsis.

Ureterovesical junction obstruction causes increment in smooth muscle contractility, and cholinergic and adrenergic activity in distal ureter of rabbits

BACKGROUND/PURPOSE

The controversy in management of primary obstructed megaureter necessitates further elucidation of the underlying pathophysiology. We evaluated smooth muscle contractility, and cholinergic, adrenergic and serotonergic activity of rabbit distal ureters after ureterovesical junction (UVJ) obstruction.

METHODS

Sham (SH) operation, partial obstruction (PO) and complete obstruction (CO) of the right UVJ were performed in rabbits. Three weeks later, distal ureters were isolated; spontaneous contractions (SC), contractile responses to electrical field stimulation (EFS), high KCl, carbachol, phenylephrine and serotonin were recorded.

RESULTS

SC amplitudes increased in CO compared to PO and SH (p<0.001). SC frequency was higher in CO (p<0.05). EFS-induced contraction amplitudes were greater in CO than other groups (p<0.05). High KCl-induced contractions were greater in CO (p<0.001) and PO (p<0.01). Carbachol-induced contractility was enhanced in CO and PO (p<0.05). Contractile response to phenylephrine was greater in CO than other groups (p<0.05). Serotonin induced contractile responses in CO and PO, greater in CO (p<0.05). UVJ obstruction also increased spontaneous contractility in contralateral PO and CO ureters.

CONCLUSIONS

UVJ obstruction increased spontaneous and neurotransmitter-induced contractions in an obstruction grade-dependent manner. Obstruction also altered contractility of the contralateral ureters. Our findings may serve to provide further understanding of the pathophysiology of megaureter.