Vitamin C deficiency in guinea pigs: variable sensitivity of collagen at different sites.

1. The synthesis of collagen in several tissues, including the C1q component of complement in serum, was measured in vitamin C-deficient and control guinea pigs by incorporating labelled proline into hydroxyproline in vivo. 2. Of the tissues examined, by far the greatest specific effect of vitamin C deficiency was observed in skin. Bone was second in order of sensitivity; skeletal muscle, lung, heart and kidney exhibited only small effects, which were difficult to distinguish from those of inanition, while liver, C1q, and the ethanol-soluble components of serum were virtually insensitive. The effect on urinary hydroxyproline was also extremely small. 3. The lack of sensitivity of C1q confirms previous conclusions (BATES, LEVENE, OLDROYD and LACHMANN 1978), based on total protein bound hydroxyproline levels and total C1 activity in plasma. Since C1q, which turns over rapidly, is insensitive, the high sensitivity of "repair" tissues to vitamin C deficiency is unlikely to be connected with their high turnover rate. Differential concentration of vitamin C by different tissues seems more likely to be the critical factor.