Prolyl hydroxylase and collagen metabolism after experimental mycardial infarction

Mature male Sprague-Dawley rats were subjected to an isoproterenol-induced myocardial infarction. Animals were sacrificed on a daily basis in order to assess the temporal changes in prolyl hydroxylase activity and collagen metabolism during the acute stages of myocardial necrosis and repair. Total myocardial hydroxyproline, as an indexof collagen content, increased promptly and markedly, beginning on day 4, and remained elevated thereafter. The incorporation of (14Cl)-proline into definitive hydroxyproline of mature collagen was also increased. The activity of the enzyme prolyl hydroxylase, which regulates the rate of conversion of proline to hydroxyproline in collagen, was elevated by day 2, remained high through day4, and then declined to a relatively constant but still slightly elevated level throughout the period of repair. It is believed that changes in these parameters of collagen metabolism reflect changes in myocardial fibroblastic cell and ground substance pertinent to fundamental aspects of repair of the injuried myocardium.