Effect of ischemia/reperfusion on bladder nerve and detrusor cell damage

Ischemia, reperfusion, and subsequent free radical damage have been implicated in many voiding disorders. Our goal was to investigate further the mechanisms of these disorders, with particular emphasis on nerve and mitochondrial function and on detrusor smooth-muscle cells. The effects on contractile responses to various stimulations, citrate synthase, choline acetyltransferase activities, and vesicular acetylcholine transporter were evaluated after ischemia alone and ischemia/reperfusion 2 h, 7 days, and 14 days. Nerve density and detrusor cell apoptosis were also measured. The contractile responses were significantly decreased at both 7 and 14 days reperfusion, although at 14 days some recovery was observed. Similar patterns were seen for the intramural nerves, both nerve cell cytoskeletal structures and cholinergic neurotransmitters. Citrate synthase activity was also depressed by ischemia and 2 h reperfusion, but the activity recovered by 7 days. Detrusor cell apoptosis was not significantly affected by ischemia and 2 h reperfusion; but showed an approximately 14-fold increase at both 7 and 14 days reperfusion. Reperfusion following ischemia resulted in worsening intramural bladder nerve dysfunction, nerve fiber injury, mitochondrial injury, and damaged detrusor muscle cells. However, at 14 days reperfusion, nerve and mitochondrial regeneration occurred and resulted in partial recovery of contractile function.     

Free radical damage as a biomarker of bladder dysfunction after partial outlet obstruction and reversal

OBJECTIVE

To investigate the use of free‐radical generation as a result of protein carbonylation and nitrotyrosination to characterize the level of bladder dysfunction after partial bladder outlet obstruction (PBOO) and reversal.

MATERIALS AND METHODS

We surgically created PBOO in male New Zealand White rabbits; after 4 weeks of PBOO, one group of six rabbits was assessed, while the PBOO was relieved in two additional groups of six rabbits each that were assessed at 4 and 8 weeks after relieving the PBOO. Six sham‐operated rabbits served as controls. Sedated rabbits were assessed by cystometry and the bladders were then removed for contractile, histological and molecular studies. Western blotting was used to determine the level of carbonylation and nitrotyrosination at the protein level.

RESULTS

The PBOO group had significant decreases in the contractile responses to field stimulation, ATP, carbachol and KCl. The responses to all forms of stimulation increased significantly at 4 weeks after reversal, and further increased to near normal levels by 8 weeks. Similarly, compliance and cystometric values also returned to near normal values after reversal. The hypertrophied smooth muscle of the obstructed bladders regressed to near‐normal size. There was a significant increase in the level of carbonylation and nitrotyrosination after PBOO, and a progressive decrease in the 4‐week reversal groups, nearing control values by 8 weeks.

CONCLUSIONS

Significantly increased carbonylation and nitrotyrosination levels after PBOO correlated with the severe dysfunction in the obstructed rabbits. Similarly, decreased levels of oxidation and nitration correlated with the functional recovery after reversal.     

Changes in the smooth muscle of the corpora cavernosum related to reversal of partial bladder outlet obstruction in rabbits

Previous studies have demonstrated that partial bladder outlet obstruction (PBOO) in the rabbit induces an increase in corpus cavernosum smooth muscle (CCSM) tone, which may make it difficult for the CCSM to relax. Thus, to determine whether the corpus cavernosum restores relaxation after reversal of PBOO, we investigated the physiologic, histologic, and cell biology in penises obtained from rabbits 4 weeks and 8 weeks after reversal of PBOO. CCSM from bladder outlet-obstructed and obstruction-reversed rabbits showed significant decreases in the contractile responses to phenylephrine. The relaxation responses to electrical field stimulation (EFS), ATP, acetylcholine, and sodium nitroprusside (SNP) were decreased in obstructed and reversed for 4 weeks groups. By 8 weeks of reversal, the relaxation of CCSM was increased gradually in response to EFS, SNP, and acetylcholine. However, the response to ATP did not result in the relaxation of CCSM to control levels. The ratio of SM to collagen decreased after obstruction and remained low after reversal. Expression of both isoforms of Rho kinase (ROK) was increased in obstruction groups. At 4 weeks of reversal, the expression of ROK alpha remained at obstruction level, whereas ROK beta expression decreased in comparison with the obstruction group. By 8 weeks of reversal, expression of both ROK alpha and beta significantly decreased when compared with the obstruction group. These results suggested that the poor relaxation response at reversal of 4 weeks was associated with incomplete decreased expression of both isoforms of ROK, whereas the incomplete recovery of the CCSM relaxation response at reversal of 8 weeks may be associated with structural alterations in the CC and irreversible damage from PBOO.     

Effect of age on the response to short-term partial bladder outlet obstruction in the rabbit

OBJECTIVE: To compare the physiological and structural changes after short-term partial bladder outlet obstruction (PBOO) in young and old rabbits, as PBOO results in marked contractile and histological alterations in the bladder. MATERIALS AND METHODS: In all, 20 young (7-8-week-old) and 20 old (2 years old) male rabbits were divided into four subgroups of five each (four obstructed and one sham control rabbit). The rabbits in the groups were evaluated after 1, 3, 7 and 14 days of PBOO, respectively. At the end of the respective periods, cystometry and contractile responses to field stimulation (FS), ATP, carbachol and potassium chloride were determined. Full-thickness sections of the bladder body and base were used to determine the vascular density, nerve density and smooth muscle/collagen ratios. RESULTS: The bladder weight of young rabbits increased at 1-7 days of PBOO and returned toward control levels at 14 days of PBOO, while in old rabbits it was higher than the control during the entire experiment. For the young rabbits, the responses to field stimulation decreased progressively for 1, 3 and 7 days, and increased significantly at 14 days. For old rabbits there was a progressive decrease to a minimal response by 3 days of PBOO and the response remained at this level over 14 days. The contractile response to ATP, carbachol and KCl were similar to the responses to FS. The vascular density in both groups increased to a maximum at 7 days and then decreased toward control values at 14 days. For the young rabbits, nerve density decreased more than in old rabbits. In the old group, the smooth muscle/collagen ratio was increased throughout PBOO and was higher than in young rabbits. The connective tissue compartment was markedly greater than in the young rabbits and the basal mucosa had vacuoles which were not apparent in the young bladders. CONCLUSIONS: This study shows that the adaptive changes to PBOO are faster in young rabbit bladders than in older rabbits.     

The effect of maturation and age on oestrogen-induced functional hypertrophy of the female rabbit bladder

OBJECTIVE: To evaluate the effect of maturation and ageing on oestrogen-induced functional hypertrophy of the female rabbit bladder. MATERIALS AND METHODS: Twenty female rabbits were separated into two groups of 10 each by age, young (immature) and old rabbits and each age group was subdivided into three subgroups. The rabbits in subgroup 1 were controls, subgroup 2 were ovariectomized (Ovx) and subgroup 3 were Ovx and received 17-beta oestradiol (1 mg/kg/day) by a subcutaneous slow-release tablet implant. After 15 days of treatment, the rabbits were killed, the bladder was excised, and the body and base separated; two full-thickness longitudinal strips from the ventral surface of the bladder body, and one full-thickness strip from the base, were prepared for contractile studies. The contractile responses to electrical-field stimulation, carbachol, ATP and KCl were determined for both the bladder body and base strips. In addition, full-thickness strips of bladder body and base were fixed in formalin for histological and immunohistological studies. RESULTS: Ovx plus oestradiol resulted in significant increases in bladder weight and responses to all forms of stimulation in young and old rabbits (except for the response to KCl). Vascular density and the smooth muscle (SM)/collagen ratio significantly increased after oestradiol replacement. Interestingly, the increase in vascular density was greater in the young than in the old rabbits. CONCLUSIONS: The present study shows that oestrogen supplementation mediates a functional hypertrophy characterized by increased contractile responses to all forms of stimulation in both young and old rabbits. The increased contractile responses might be explained by the increases in vascular density and SM/collagen ratio.     

Protective effect of Antrodia Camphorata on bladder ischemia/reperfusion injury

Introduction  

Obstructive bladder dysfunction is directly related to ischemia/reperfusion injury characterized by damage to nerves, synapses and smooth muscle cells within the bladder wall. Antrodia Camphorata (AC) has significant antioxidant, antiinflammatory and cell-cycle inhibition properties. The specific aim of this study was to evaluate whether orally administered AC can protect rabbit bladders from the progressive dysfunctions induced by bilateral ischemia/reperfusion (I/R).