Smooth-muscle myosin heavy-chain isoform expression in bladder-outlet obstruction.
Bladder-outlet obstruction leads to detrusor smooth-muscle hypertrophy/hyperplasia. Despite this overall increase in muscle mass, smooth-muscle contractility decreases and bladder emptying is impaired. The goal of this study was to determine whether smooth-muscle myosin heavy-chain (MHC) alterations occur in conjunction with partial obstruction of the rabbit bladder. Total MHC and MHC-isoform protein concentrations were determined by quantitative gel electrophoresis in rabbit bladders partially obstructed for 1-4 weeks. MHC gene expression was assessed by Northern and nuclease protection assays. Two MHC isoforms (SM1/SM2) were identified in the normal rabbit bladder. After 2 weeks of obstruction the ratio of SM1/SM2 changed from 0.4:0.6 to 0.5:0.5 (P < 0.01). As compared with sham-operated values, the level of MHC mRNA decreased significantly as of 1 day after obstruction. Quantitation of MHC-isoform mRNA levels revealed a nearly 3-fold increase in the SM1/SM2 ratio. In this animal model of bladder-outlet obstruction, early changes in MHC isoforms as well as an overall decrease of MHC mRNA expression were demonstrated, suggesting that obstruction induces significant alterations in myofilament gene expression.
Cher
M L
ML
Division of Urology, University of Texas, Southwestern Medical Center, Dallas 75235-9110, USA.
Abernathy
B B
BB
McConnell
J D
JD
Zimmern
P E
PE
Lin
V K
VK
D000818:Animals; D015152:Blotting, Northern; D004247:DNA / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D015870:Gene Expression; D006965:Hyperplasia / Q000378:metabolism / Q000473:pathology; D008297:Male; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D018995:Myosin Heavy Chains / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis*; D011817:Rabbits; D001748:Urinary Bladder Neck Obstruction / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
D012333:RNA, Messenger; D004247:DNA; D018995:Myosin Heavy Chains