Effects of outlet obstruction and its reversal on mitochondrial enzyme activity in rabbit urinary bladders

Phosphodiesterase (PDE) inhibitors in the treatment of lower urinary tract dysfunction

Several disorders of the human upper and lower urinary tract, such as urinary stone disease, lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH) and detrusor overactivity, can be therapeutically addressed by influencing the function of the smooth musculature of the ureter, prostate or urinary bladder, respectively. In order to ensure a drug effect without significant adverse events, a certain degree of tissue selectivity is mandatory. The treatment of said conditions aims to focus on orally available drugs acting via intracellular signalling pathways. Specifically, the cyclic nucleotide monophosphate cyclic GMP represents an important mediator in the control of the outflow region (bladder, urethra). The use of phosphodiesterase (PDE) inhibitors, such as sildenafil, tadalafil, vardenafil, avanafil or udenafil, known to restrain the degradation of the second messenger cyclic GMP, offers great opportunities in the treatment of lower urinary tract dysfunction. PDE inhibitors are regarded as efficacious, have a rapid onset of action and favourable effect-to-side-effect ratio. The role of PDE5 inhibitors in the treatment of BPH/LUTS and the overactive bladder has already been addressed in randomized, double-blind, placebo-controlled trials, as well as preliminary open-label studies enrolling either several hundreds or only 20 patients. The purpose of this review is to focus on the potential use and clinical significance of PDE inhibitors in the treatment of storage and voiding dysfunctions of the lower urinary tract. The strategy of modulating the activity of PDE isoenzymes might represent a novel approach in patients with lower urinary tract dysfunction (LUTD).

Effect of co-enzyme Q10 and alpha-lipoic acid on response of rabbit urinary bladder to repetitive stimulation and in vitro ischemia

OBJECTIVES

To determine the efficacy of coenzyme Q10 (CoQ10) and alpha-lipoic acid (alpha-LA), either alone or in combination, to protect the contractile responses of the rabbit urinary bladder from damage caused by repetitive stimulation in the presence or absence of in vitro ischemia.

METHODS

Four groups of New Zealand white rabbits (4 per group) were treated with vehicle (group 1), CoQ10 (group 2), alpha-LA (group 3), or CoQ10 plus alpha-LA (group 4) for 2 weeks. At the end of the treatment period, eight longitudinal strips from each rabbit bladder body were placed in oxygenated Tyrode's solution with glucose (normal physiologic medium). The strips were stimulated by field stimulation, carbachol, and KCl, and the responses were recorded. One half of the strips were switched for 1 hour to Tyrode's solution with no glucose equilibrated with nitrogen (ischemia medium). Simultaneously, all strips were subjected to 1 h of repetitive field stimulation followed by 1 hour of recovery in normal physiologic medium, and the responses to all stimuli were recorded again.

RESULTS

CoQ10 showed no protective effect. Alpha-LA resulted in increased contractile responses of the control bladder and showed a moderate protective effect for all forms of stimulation. The combination, however, showed a significantly greater increase in the contraction of the control bladder and a greater protective effect than alpha-LA alone.

CONCLUSIONS

The combination of alpha-LA and CoQ10 treatment enhanced the contractile response in normal medium and diminished the contractile dysfunction induced by repetitive field stimulation and ischemia.

Hypoxia preconditioning attenuates bladder overdistension-induced oxidative injury by up-regulation of Bcl-2 in the rat

We explored whether hypoxic preconditioning minimizes oxidative injury induced by overdistension/emptying in the rat bladder. For hypoxic preconditioning, female Wistar rats were placed in a hypobaric chamber (380 Torr) 15 h day(-1) for 28 days. Overdistension was induced by infusion of two times the threshold volume of saline into the bladder and was maintained for 1 or 2 h, followed by drainage/emptying. During overdistension (ischaemia) and emptying (reperfusion) periods, a bursting increase of reactive oxygen species (ROS) from the bladder was originated from the large numbers of infiltrating leucocytes and scattered resident cells, including urothelial, submucosal, and smooth muscle cells. ROS impaired the voiding function by a reduction of bladder afferent and efferent nerve activity and bethanecol- or ATP-induced detrusor contraction. ROS enhanced pro-apoptotic mechanisms, including increases in the Bax/Bcl-2 ratio, CPP32 expression, and poly(ADP-ribose) polymerase (PARP) fragments with subsequent apoptotic cell formation in the insulted bladders. Hypoxia preconditioning up-regulated Bcl-2 expression in the bladder and significantly reduced the levels of ROS and apoptosis detected in the overdistension/emptying bladders and preserved partial voiding function. Bcl-2 up-regulation by hypoxia preconditioning contributes protection against overdistension/emptying-induced oxidative stress and injury in the bladder.