Activation of Prolyl Hydroxylase in Sponge Induced Granulation Tissue: The Effect of Antineutrophil Serum and Inhibitor Drugs

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Abstract
Prolyl hydroxylase activity in rat and rabbit sponge induced granulation tissue was studied as a function of time after implantation. The method of expression of such data was critical in determination of the shape of the curve. The method of data expression used in this paper was, cpm/μg of fibrocyte and fibroblast (F-DNA) or cpm per μg hydroxyproline. Use of other parameters such as extractable protein, wet weight or total DNA changed the shape of the curve and obscured the rapid increases in prolyl hydroxylase activity occurring during the first 48 hours. Giemsa and fast green staining was found to be a useful method for identification of fibroblasts in tissue sections. The use of this stain facilitated the large number of differential counts necessary for the calculation of F-DNA from total DNA values. Rats were treated with cyclophosphamide or antineutrophil serum to deplete them of neutrophils and monocytes. Such treatment failed to inhibit the usual increase in prolyl hydroxylase occurring in granulation tissue by the third day. In the rabbit an early 2–3 fold increase in prolyl hydroxylase activity in vivo was observed four hours after sponge implantation. This early increase in activity was blocked by inhibitors of RNA and protein synthesis and was considered to be dependent on new protein synthesis rather than on activation of a proenzyme.