Mb. Ganz et A. Seftel, Glucose-induced changes in protein kinase C and nitric oxide are preventedby vitamin E, AM J P-ENDO, 278(1), 2000, pp. E146-E152
Citations number
40
Categorie Soggetti
Endocrinology, Nutrition & Metabolism
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM
Changes in activity or expression of protein kinase C (PKC), reactive oxyge
n products, and nitric oxide (NO) may account for the alteration in cell be
havior seen in diabetes. These changes have been proposed to be part of the
pathophysiology of erectile dysfunction. We sought to ascertain if corpus
cavernosal vascular smooth muscle cells (CCSMC) grown in a high glucose mil
ieu exhibit changes in the activity and expression of PKC isoforms, NO, and
reactive oxygen products and to find out if these changes are prevented by
alpha-tocopherol. Rat CCSMC were grown in 5, 15, and 30 mM glucose concent
rations for 3, 7, and 14 days. PKC isoform expression was assayed with isof
orm-specific antibodies. In CCSMCs grown in 30 mM glucose for 2-wk, PKC-bet
a(2)-isoform was upregulated (n = 4; P < 0.01), whereas the expression of a
lpha-, delta-, epsilon-, and beta(1)-isoforms was unchanged. NO as measured
by nitrate-to-nitrite ratio was greatly diminished at 14 days in 30 mM (n
= 4; P < 0.002) compared with 5 mM glucose. Reactive oxygen products were u
pregulated at 14 days when they were assayed by the fluorescent probe dichl
orofluorescein diacetate bis(acetoxy-methyl) (DCFH-DA) (n = 5; P < 0.01). W
hen these same cells were exposed to alpha-tocopherol for 14 days, there wa
s a reduction of PKC-beta(2) (57.8%; P < 0.01; n = 4) and a reduction in re
active oxygen product formation (71.1%; P < 0.001; n = 4), along with an in
crease in nitrate-to-nitrite ratio (43.9%; P < 0.01, n = 4). These results
suggest that there may be an interrelationship between PKC, NO, and reactiv
e oxygen product formation in CCSMC exposed to a high glucose environment.