The Comparative Study Of The Change Of Detrusor Excitability After Suprasacral Cord Injury Or BOO

Background and Objective Suprasacral cord injury (SSCI) usually lead to detrusor hyperreflexia(DH),and the mechanism of DH remains unclear. There are two predominant approaches that have been pursued to understand the bases of these problems: (1) studies of neural control of lower urinary tract function, and (2) measurement of the cellular properties of the component tissues of the bladder wall—principally,the detrusor smooth muscle, but the previous study were confined to neuropathology. It is defect to study the relationship of detrusor following changes after Suprasacral cord injury with bladder voiding dysfunction.It is necessary that detrusor occurs following changes after Suprasacral cord injury, and the occurrence of bladder voiding dysfunctions is related to the following changes of detrusor.It can help to make clear the mechanism of DH after Suprasacral cord injury betterly to study the detrusor myogenic change after Suprasacral cord injury.The pathogenesis about suprasacral cord injury leading to DH is not clear. Bladder outlet obstruction(BOO)usually leads to detrusor instability(DI).Some study demonstratate that the detrusor excitability increase in DI.On these grounds,it were established that detrusor myogenic change leads to DI.The symptoms of DH and DI are similar,except the nerve injury,it requires further study wether there is common in the pathogenesis of DH and DI.The detrusor following changes after suprasacral cord injury include the changes of excitability,contractibility and compliance.The change of excitability is related to detrusor hyperreflexia,and the change of compliance influence the vesical function of storing urine.The generation and conduction of excitation are important to detrusor contraction,and the contents of actin, typeⅢand typeⅠcollagen fibrils is related to detrusor compliance,having the allround study about this can help to make clear the relationship between the neurogenic bladder and the non-neur factors.It has been illuminated that detrusor excitation is evoked by calcium influx through calcim channel,and the rhythmic contraction is related to calcium oscilation formmed by rhythmic calcium releasing from calcium storeroom.So calcium ion is related to detrusor excitation and contraction closely. Both L- and T-type Calcium channels are present in detrusor cells. Studying the changes of detrusor calcium channel and calcium oscilation after suprasacral cord injury is important to make cleare the mechanism of detusor excitability change after suprasacral cord injury.The excitation of detrusor intercellular is conducted through electrical coupling,and gap junction is one kind electrical coupling. Connnexin43 is the important constitutive protein of gap junction,and the express change can reflect the change of excitation conduction intercellular.On account of the above findings, we plan to detect the changes of detrusor excitability after suprasacral cord injury or BOO, observe the effect of myogenic factors in neurogenic bladder, and elucidate the pathogenesis of DH in the present study.Methods Animal models at 4 weeks after suprasacral cord injury or BOO were made in female SD rats.Cystometry in vivo and in vitro, mechanical pulling and pharmacal stimulate tests of isolated detrusor strips were performed, and the change of Connnexin43,β-actin, typeⅠand typeⅢcollagen fibers were detected by immunohistochemistry.Calcium oscilation were observed by laser confocal microscope.Resuls 1 The bladder emergence DH, and the compliance decresed after suprasacral cord injury .The incidence rate of DI was 68.7% after BOO.2 No rhythmicity contraction occurred during the course of vivo and vitro cystometry in control group .Rhythmicity contraction occurred at lower pressure in DH and DI groups,regardless of in vivo or in vitro.The frequence of contraction in vitro were higher than in vivo significantly(P<0.05). 3 The tension that induce isolated detrusor contraction by mechanical pulling in DH and DI groups was lower than the control group,and the contraction frequence at the same preload was higher than the control group(P<0.05).4 With the high concentration carbocholine stimulating, the detrusor contraction force of each group were same,so as to with the high concentration noradrenaline or ATP stimulating.5 The contraction frequence of three groups decreased to the same level after dropwising high concentration mibefradil(blocker of T-type calcium channel) ,and the decrease of contraction frequence were same after dropwising high concentration verapamil(blocker of L-type calcium channel).6 The Ca2+ oscillation frequence of detrusor cell in DH and DI group was higher than the control group(P<0.05). when dropwising high concentration mibefradil ,the frequence of three groups decreased to the same level ,and when dropwising high concentration verapamil,the decrease of frequence was same.7 as compare with control group,the Connnexin43,β-actin, typeⅢand typeⅠcollagen fibrils in DH or DI increased significantly.Conclussion There is concordance for detrusor myogenic change after suprasacral cord injury and BOO,just as DI,the occurrence of DH is related to the detrusor myogenic chang after suprasacral cord injury .1. The Detrusor compliance decrese after suprasacral cord injury or BOO.2. The detrusor occur following change,and the excitability increase after suprasacral cord injury or BOO.3. The character change of T-type calcium channel leads to the increase of detrusor excitability probably, and the change of L- type calcium channel has little effect in the development of DH or DI.4. The express of detrusor connexin43 increase after suprasacral cord injury or BOO.This change indicates the increase of excitation conduction intercellular,and the development of DH or DI is related to the increase of excitation conduction too.5.The increase ofβ-actin, type-Ⅲand type-Ⅰcollagen fibrils lead to the decrease of bladder compliance.6. There is common pathogenesis in the development of DI and DH,that is detrusor myogenic change is related to DH or DI closely.