5-[5-(2-Nitrophenyl) furfuryliodine]-1,3-diphenyl-2-thiobarbituric acid 
(UCF-101) is a protease inhibitor which was reported to protect against 
ischaemic heart damage and apoptosis. This study evaluated the impact of UCF-101 
on steptozotocin (STZ)-induced diabetic cardiomyocyte dysfunction. Adult FVB 
mice were made diabetic with a single injection of STZ (200 mg kg(1)). Two weeks 
after STZ injection, cardiomyocytes from control and STZ-treated mice were 
isolated and treated with UCF-101 (20 mum for 1 h). Cardiomyocyte contractile 
properties were analysed, including peak shortening (PS), maximal velocity of 
shortening/relengthening (+/-dL/dt), time to PS (TPS) and time to 90% 
relengthening (TR(90)). Steptozotocin-induced diabetes depressed PS and +/-dL/dt 
and prolonged TPS and TR(90) in cardiomyocytes, all of which were significantly 
alleviated by UCF-101. Immunoblotting analysis showed that UCF-101 significantly 
alleviated STZ-induced loss of phospholamban phosphorylation without affecting 
sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA2a) and phospholamban. 
Steptozotocin reduced AMP-activated protein kinase (AMPK) phosphorylation at 
Thr172 of the catalytic subunit without affecting total AMPK expression, which 
was restored by UCF-101. Short-term exposure to UCF-101 did not change the 
expression of X-linked inhibitor of apoptosis protein (XIAP) and Omi 
stress-regulated endoprotease, high temperature requirement protein A2 
(Omi/HtrA2), favouring an apoptosis-independent mechanism. Both the AMPK 
activator resveratrol and the antioxidant N-acetylcysteine mimicked the 
UCF-101-induced beneficial effect in STZ-induced diabetic cardiomyocytes. In 
addition, UCF-101 promoted the phosphorylation of p38 mitogen-activated protein 
kinases and c-Jun N-terminal kinase (JNK) after 15 min of incubation, while it 
failed to affect the phosphorylation of extracellular signal-regulated kinase 
(ERK) and glycogen synthase kinase-3beta (GSK-3beta) within 120 min in H9C2 
myoblasts. Taken together, these results indicate that UCF-101 protects against 
STZ-induced cardiomyocyte contractile dysfunction, possibly via an 
AMPK-associated mechanism.