The effect of ischemia/reperfusion on rabbit bladder--role of Rho-kinase and smooth muscle regulatory proteins.
OBJECTIVE
To detect the effect of ischemia/reperfusion (I/R) injury on rabbit bladder, using physiological study and immunoblotting techniques.


METHODS
Twelve male New Zealand White rabbits were separated into three groups of 4 rabbits each. Group 1 served as control. Group 2 rabbits (ischemia-alone group) underwent in vitro bilateral ischemia surgery for 2 hours. In group 3 (I/R group), bilateral ischemia was similarly induced, and the rabbits were allowed to recover for 2 weeks. The contractile responses to electrical field stimulation, adenosine triphosphate, carbachol, and KCl were recorded. Expression levels of the signaling targets, Rho-kinase (ROK), protein kinase C potentiated inhibitor (CPI-17), caldesmon (CaD), and calponin (CaP) were analyzed by Western blotting.


RESULTS
Ischemia alone resulted in significant reductions in the contractile responses, whereas I/R resulted in further decreases after all forms of stimulation. In muscle layer, ROK expression increased immediately after ischemia and recovered to the control level after 2 weeks' recovery. However, in mucosa layer, ROK expression showed no significant change after ischemia but significantly increased after reperfusion. After ischemic damage, CPI-17, the functional protein involved in smooth-muscle Ca(2+) sensitization, was significantly increased and then decreased after 2 weeks of reperfusion. The expression of CaP significantly increased after ischemia and decreased after reperfusion. Levels of high-molecular-weight CaD significantly decreased after ischemia and remained very low after reperfusion.


CONCLUSIONS
This study provides further understanding of the role of regulatory proteins in detrusor muscle after ischemia and I/R-induced contractile dysfunction.
Juan
Yung-Shun
YS
Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
Li
Suning
S
Levin
Robert M
RM
Kogan
Barry A
BA
Schuler
Catherine
C
Leggett
Robert E
RE
Huang
Chun-Hsiung
CH
Mannikarottu
Anita
A
D000818:Animals; D015153:Blotting, Western; D002148:Calmodulin-Binding Proteins / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D003285:Contractile Proteins / Q000187:drug effects / Q000378:metabolism*; D004195:Disease Models, Animal; D004591:Electrophoresis, Polyacrylamide Gel; D007511:Ischemia / Q000201:enzymology* / Q000503:physiopathology; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D011336:Probability; D011817:Rabbits; D011897:Random Allocation; D038621:Regulatory Sequences, Ribonucleic Acid / Q000187:drug effects / Q000502:physiology; D015427:Reperfusion Injury / Q000201:enzymology* / Q000503:physiopathology; D012680:Sensitivity and Specificity; D001743:Urinary Bladder / Q000293:injuries / Q000503:physiopathology*; D054460:rho-Associated Kinases / Q000378:metabolism*
D002148:Calmodulin-Binding Proteins; D003285:Contractile Proteins; D038621:Regulatory Sequences, Ribonucleic Acid; D002217:Carbachol; D054460:rho-Associated Kinases