Endothelial cell permeability is impaired in diabetes mellitus and may be increased by high extracellular glucose concentrations. High glucose activates protein kinase C (PKC), a family of kinases vital to intracellular signaling. We tested the hypothesis that high glucose concentration activates PKC in endothelial cells and leads to an increase in endothelial cell permeability via distinct PKC isoforms. Porcine aortic endothelial cells were used, and the PKC isoforms alpha, delta, epsilon, zeta, and theta were identified in these cells. Glucose caused a rapid dose-dependent increase in endothelial cell permeability, with an EC50 of 17.5 mmol/L. Phorbol 12-myristate 13-acetate (TPA) induced an increase in permeability very similar to that elicited by glucose. The effect of glucose and TPA was totally reversed by preincubating the cells with the PKC inhibitors staurosporine (10(-8) mol/L) and Goe 6976 (10(-8) mol/L). Downregulation of PKC by preincubation with TPA for 24 hours also abolished the effect of glucose and TPA on endothelial cell permeability. High glucose (20 mmol/L) caused an increase in PKC activity at 2, 10, and 30 minutes. Cell fractionation and Western blot analysis showed a glucose-induced translocation of PKC alpha and PKC epsilon. Confocal microscopy confirmed the translocation and showed an association of PKC alpha and PKC epsilon with nuclear structures and the cell membrane. Specific antisense oligodesoxynucleotides (ODNs) against PKC alpha reduced the expression of the isoform, abolished the effects of glucose on endothelial cell permeability completely, and reduced the TPA effect significantly. In contrast, specific antisense ODNs against PKC epsilon had no effect on glucose-induced permeability and only a minor effect on the TPA-induced increase in permeability. We conclude that an increase in extracellular glucose leads to a rapid dose-dependent increase in endothelial cell permeability via the activiation of PKC and that this effect is mediated by the PKC isoform alpha.

Our results suggest that training-related cerebral activation changes follow an inverse U-shaped quadratic function and raise the prospect of investigating cerebral mechanisms underlying training effects.

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We examined a Turkish kindred with a unique form of autosomal dominant hypertension that cosegregates 100% with brachydactyly and maps to chromosome 12p. Affected adults were 10 to 15 cm shorter than unaffected people; however, their body mass index (27 kg/m2) was not different. Blood pressure increased steeply with age in the affected people so that by age 40 years, they had a mean blood pressure of 140 mm Hg, compared with 92 mm Hg in unaffected individuals. Complete clinical, roentgenographic, and laboratory evaluation was performed in 6 subjects, including 24-hour blood pressure measurements and humoral determinations before and after volume expansion with 2 L normal saline over 4 hours followed by volume contraction on the following day with a 20-mmol sodium diet and 40 mg furosemide at 8 AM, noon, and 4 PM. Two affected men aged 46 and 31 years; 3 affected women aged 40, 31, and 30 years; and 1 unaffected man aged 29 years were studied. Systolic pressures ranged from 170 to 250 mm Hg, and diastolic pressures ranged from 100 to 150 mm Hg in affected people; the unaffected man had a blood pressure of 120/70 mm Hg. Thyroid, adrenal, and renal functions were normal; electrolyte and acid-base statuses were normal. Calcium and phosphate homeostasis was normal. Day-night circadian blood pressure rhythm was preserved. The subjects were not salt sensitive; renin, aldosterone, and catecholamine values reacted appropriately to volume expansion and contraction. Affected people had mild cardiac hypertrophy and increased radial artery wall thickness. Fibroblasts from affected people grew more rapidly in culture than from unaffected people. We conclude that this novel form of inherited hypertension resembles essential hypertension.