Protein kinase C activation contributes to microvascular barrier dysfunction in the heart at early stages of diabetes.
The functional disturbance of microvasculature is recognized as an initiating mechanism that underlies the development of various diabetic complications. Although a causal relationship between microvascular leakage and tissue damage has been well documented in diabetic kidneys and eyes, there is a lack of information regarding the barrier function of coronary exchange vessels in the disease state. The aim of the present study was to evaluate the permeability property of coronary microvessels during the early development of experimental diabetes with a focus on the protein kinase C (PKC)-dependent signaling mechanism. The apparent permeability coefficient of albumin (Pa) was measured in isolated and perfused porcine coronary venules. The administration of high concentrations of D-glucose induced a dose-dependent increase in the Pa value, which was prevented by blockage of PKC with its selective inhibitors bisindolylmaleimide and Goe 6976. More importantly, an elevated basal permeability to albumin was observed in coronary venules at the early onset of streptozotocin-induced diabetes. The hyperpermeability was corrected with bisindolylmaleimide and the selective PKCbeta inhibitor hispidin. Concomitantly, protein kinase assay showed a high PKC activity in isolated diabetic venules. Immunoblot analysis of the diabetic heart revealed a significant subcellular translocation of PKCbetaII and PKCepsilon from the cytosol to the membrane, indicating that the specific activity of these isoforms was preferentially elevated. The results suggest that endothelial barrier dysfunction attributed to the activation of PKC occurs at the coronary exchange vessels in early diabetes.
Yuan
S Y
SY
Departments of Surgery and Medical Physiology, Cardiovascular Research Institute, Texas A&M University System Health Science Center, Temple, TX 76504, USA. yuan@tamu.edu
Ustinova
E E
EE
Wu
M H
MH
Tinsley
J H
JH
Xu
W
W
Korompai
F L
FL
Taulman
A C
AC
D000418:Albumins; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects; D002478:Cells, Cultured; D003326:Coronary Circulation / Q000502:physiology*; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D004730:Endothelium, Vascular / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D005947:Glucose / Q000494:pharmacology; D006321:Heart / Q000503:physiopathology*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000032:analysis; D008833:Microcirculation / Q000503:physiopathology*; D010477:Perfusion; D011493:Protein Kinase C / Q000032:analysis / Q000502:physiology*; D013552:Swine; D013997:Time Factors
D000418:Albumins; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D007527:Isoenzymes; D011493:Protein Kinase C; D016650:Fluorescein-5-isothiocyanate; D005947:Glucose