Selective inhibition of protein kinase C beta(2) attenuates inducible nitric oxide synthase-mediated cardiovascular abnormalities in streptozotocin-induced diabetic rats.
OBJECTIVE
Impaired cardiovascular function in diabetes is partially attributed to pathological overexpression of inducible nitric oxide synthase (iNOS) in cardiovascular tissues. We examined whether the hyperglycemia-induced increased expression of iNOS is protein kinase C-beta(2) (PKCbeta(2)) dependent and whether selective inhibition of PKCbeta reduces iNOS expression and corrects abnormal hemodynamic function in streptozotocin (STZ)-induced diabetic rats.


METHODS
Cardiomyocytes and aortic vascular smooth muscle cells (VSMC) from nondiabetic rats were cultured in low (5.5 mmol/l) or high (25 mmol/l) glucose or mannitol (19.5 mmol/l mannitol + 5.5 mmol/l glucose) conditions in the presence of a selective PKCbeta inhibitor, LY333531 (20 nmol/l). Further, the in vivo effects of PKCbeta inhibition on iNOS-mediated cardiovascular abnormalities were tested in STZ-induced diabetic rats.


RESULTS
Exposure of cardiomyocytes to high glucose activated PKCbeta(2) and increased iNOS expression that was prevented by LY333531. Similarly, treatment of VSMC with LY333531 prevented high glucose-induced activation of nuclear factor kappaB, extracellular signal-related kinase, and iNOS overexpression. Suppression of PKCbeta(2) expression by small interference RNA decreased high-glucose-induced nuclear factor kappaB and extracellular signal-related kinase activation and iNOS expression in VSMC. Administration of LY333531 (1 mg/kg/day) decreased iNOS expression and formation of peroxynitrite in the heart and superior mesenteric arteries and corrected the cardiovascular abnormalities in STZ-induced diabetic rats, an action that was also observed with a selective iNOS inhibitor, L-NIL.


CONCLUSIONS
Collectively, these results suggest that inhibition of PKCbeta(2) may be a useful approach for correcting abnormal hemodynamics in diabetes by preventing iNOS mediated nitrosative stress.
Nagareddy
Prabhakara Reddy
PR
Faculty of Pharmaceutical Sciences, The University of British Columbia, British Columbia, Canada.
Soliman
Hesham
H
Lin
Guorong
G
Rajput
Padmesh S
PS
Kumar
Ujendra
U
McNeill
John H
JH
MacLeod
Kathleen M
KM
D000818:Animals; D001011:Aorta / Q000201:enzymology; D001786:Blood Glucose / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000517:prevention & control*; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D003925:Diabetic Angiopathies / Q000517:prevention & control*; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005947:Glucose / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology*; D008239:Lysine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D008301:Maleimides / Q000494:pharmacology*; D008353:Mannitol / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000201:enzymology; D032383:Myocytes, Cardiac / Q000166:cytology / Q000201:enzymology*; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D064546:Protein Kinase C beta; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D004791:Enzyme Inhibitors; D007211:Indoles; D008301:Maleimides; C090663:N(6)-(1-iminoethyl)lysine; D008353:Mannitol; C099154:ruboxistaurin; D052247:Nitric Oxide Synthase Type II; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D005947:Glucose; D008239:Lysine