The Change Of The Level Of The Ryanodine Receptor2 In The Underactive Detrusor Of Patients Due To Benign Prostatic Hyperplasia

ObjectsBenign prostatic hyperplasia ( BPH) is a common clinical disease of the department of urology. Old males often suffer from the secondary underactive de-trusor( UAD) due to BPH. The main clinical manifestations of UAD are a series symptoms of dysuria, such as urinary hesitancy, postvoid dribbling and straining, etc. Even leads to the damage of the upper urinary tract. Most researches at present are concerned with the bladder outlet obstruction and the unstable bladder of the BPH patients, less of them with the UAD due to BPH. Researches show that a key role of the excitation - contraction coupling is Ryanodine receptor ( RyR) and the only subtype of RyR in the human detrusor is RyR₂. But the current researches to RyR are mostly about the RyR of cardiac muscle, skeletal muscle and vascular smooth muscle. There is no research about the contribution of the RyR₂ to the onset mechanism of the UAD due to BPH.To identify whether the RyR₂ contributes to the onset of UAD due to BPH or not, we tested the levels of mRNA and protein of RyR₂ in the human detrusor specimens by RT - PCR and Western blot. And the study could provide the rational to the onset mechanism of the UAD due to BPH.Methods60 patients who performed the open operations for BPH were included. All of them took the urodynamic examination. The existence of UAD was judged by the linearized passive urethral resistance relation (LinPURR). Group A was defined as 20 patients with UAD and Group B as 40 patients without UAD. Took the bladder detrusor of the patients as the specimens. RT - PCR was used to measure the change of the mRNA of RyR₂ in both groups. The cDNA amplifying product of β - actin was used as a internal reference. The ratio of RyR₂ cDNA amplifying product to β -actin was used to reflex the mRNA level of RyR₂- At the same time, Western blot was used to detect the change of RyR2 protein level of both groups. The level of RyR₂ protein was determined by scanning densitom-etry. All datas were presented as x ± s. The SPSS 11.0 for windows was used to analysis the data. The t test was used to test the differences between two groups. P<0.05 was considered to be statistically significant.ResultsThere are two groups; the BPH patients with UAD and without UAD. The ratio of the concentration of RyR₂ cDNA amplifying product to β - actin of the Group A and Group B was 72.5% ± 19.0% and 132. 5% ±32.7% , respectively. The level of RyR₂ protein was 45.2 ± 8. 6 and 135. 2 ±23. 6, respectively. The levels of RyR₂ mRNA and protein of the Group A decreased significantly ( P <0.01 ,n =20). These suggest there are alterations in either the transcriptional rate or mRNA stability of RyR₂ under the UAD condition. The decrease of RyR₂ protein level may be due to decreased rate of protein synthesis and increased degradation.Conclusions1. The RyR₂ mRNA level of the BPH patients with UAD decreased signifi-...