Vitamin C deficiency in guinea pigs differentially affects the expression of type IV collagen, laminin, and elastin in blood vessels

Vitamin C deficiency causes morphologic changes in the endothelial and smoo th muscle compartments of guinea pig blood vessels. Endothelial cells synth esize the basement membrane components, type IV collagen and laminin, and s mooth muscle cells synthesize elastin in blood vessels. Therefore, we exami ned the possibility that vitamin C deficiency affects the expression of the se proteins. Decreased expression of types I and II collagens in other tiss ues of vitamin C-deficient guinea pigs is associated with weight loss and t he consequent induction of insulin-like growth factor binding proteins; thu s we also used food deprivation to induce weight loss. Female guinea pigs r eceived a vitamin C-free diet, supplemented orally with ascorbate. Vitamin C-deficient guinea pigs received the same diet but no ascorbate, and the fo od-deprived group received no food, but were supplemented with vitamin C. C oncentrations of mRNAs far basement membrane components and elastin in bloo d vessels were measured by Northern blotting; overall basement membrane met abolism was assessed by measuring immunoreactive laminin and type IV 7S col lagen in serum. Laminin mRNA in blood vessels and serum laminin concentrati ons were unaffected by vitamin C deficiency. Concentrations of type IV coll agen and elastin mRNAs in blood vessels were not significantly affected in moderately scorbutic guinea pigs (0-7% weight loss), but with increased wei ght loss, type IV collagen mRNA was 57% (P < 0.05) and elastin mRNA was 3% (P < 0.01) of normal values. In food-deprived guinea pigs, type IV collagen mRNA was 51% (P < 0.05) and elastin mRNA was 35% (P < 0.05) of normal. Ser um type IV 7S collagen concentrations were 25% of normal in scorbutic guine a pigs with extensive weight loss. The lower expression of type IV collagen and elastin mRNAs in blood vessels may contribute to defects observed in b lood vessels during scurvy.