A Study On Relationship Between Low Compliant Bladder And Fiber Components Of Bladder Wall

Cystic malfunction can result in various abnormal functions of urine storage and micturition in the lower urinary tract. The most common cystic malfunction includes three types: abnormality in contractility of detrusor, abnormality in excitability of the detrusor and abnormality in cystic compliance. The low compliant bladder is characterized by: 1) low cystic capacity and significant increase of pressure; 2) It is the common result of various cystic and lower urinary tract lesions such as congenital or acquired obstruction of the urinary bladder, neurological micturition disorder and chronic cystitis etc.; 3) urinary frequency, urinary urgency and stress incontinence etc.; 4) It is the main reason for upper urinary tract damage resulting from lower urinary tract lesions and the severe low compliant bladder may limit emptying capacity of the bladder; 5) After treatment of the primary diseases, some milder cases of low compliant bladder may automatically relieved. However, for those severe cases, though the primary diseases had been controlled, the phenomenon of low compliant bladder can not be eliminated but further developed to result in damage of the upper urinary tract.Up to now, the reasons for obstructive low compliant bladder have not been elucidated. Early pathological studies confirmed that there are hypertrophy and hyperplasia of muscle as well as increase of fiber tissue in the cystic wall after chronic urinary tract obstruction. Both of these two factors can cause decrease in cystic compliance, which has not directly been confirmed by experiments. However, the following data indicate that increase in collagen and decrease in elastin fibers are the major pathogenic bases for low compliant bladder: 1) Mechanical kinetic studies reveal that muscular tension plays an important role inearly stage of cystic pressure formation. That is to say, increase in cystic pressure at the early stage of cystic congestion is related to muscular tension. In the late stage of cystic congestion, the cystic pressure is mainly associated with hardness of the fibers; 2) In those cases of severe low compliant bladder, the proportion of muscle decreases while that of fibrotic and connective tissues increase in cystic bladder. This indicates that tension of detrusor is not the major reason for low compliant bladder; 3) Some treatments for inhibition of contractility of detrusor can reduce its contractility but can not eliminate the phenomenon of low compliant bladder; 4) The increase in collagen and decrease in elatin fibers have been confirmed to be the major reason for sclerosis of such organs and tissues as the lung, blood vessel and skin etc. Unfortunately, only few reports about the relationship between low compliant bladder and collagen and elastin fibers have been published. It has been reported that type III collagen decreases in patients with obstructive low compliant bladder. Meanwhile, MMP-1 decreases but TIMP1 increases in cystic tissue in patients with low urinary bladder obstruction. The imbalance between the enzyme and enzyme inhibitor might be related to increase in type III collagen. However, the reports about the relationship between elastin fibers and bladder compliance are rare.In order to explore the relationship between low compliant bladder and fiber construction of the cystic wall, we performed the following experiments: 1) After the model of obstructive low compliant bladder was established in rats, morphological changes of the cystic wall were observed with light and electron microscopy and alterations in contents of collagen and elastin fibers determined by immunohistochemistry and RT-PCR etc. 2) The adenovirus vector containing genes of MMP13 and Tropoelastin was constructed and identified. 3) The cystic tissue was extracted from the rats for culture of primary detrusor cells. The rat's cystic smooth muscle cells were transfected by the virus supernatant containing MMP13 and Tropoelastin. The transfection was confirmed by immunohistochemistry and PCR. Finally, the rat bladder was transfect...