Collagenase degrades collagen in vivo in the ischemic heart

Previously, we showed that ischemic rat heart contains an activated procoll agenase capable of degrading collagen in vitro. We now demonstrate that the collagen resident in such hearts (in vivo) also becomes degraded, producin g characteristic fragments implicating the action of an activated collagena se. The evidence is the appearance of amino-terminal dansyl-Ile (+dansyl-Le u) residues in pepsin digests of re-oxygenated rat hearts and immunoblots s howing 3/4 length (alpha A) fragments from type I collagen. Also, in ischem ic rat myocardium, alpha A(I) and alpha A(III) fragments were detected in p epsin digests. The time periods required for the cleavage and degradation o f collagen suggest the participation of a procollagenase that becomes activ ated. Results demonstrate for the first time that an interstitial collagena se in such hearts initiates in vivo degradation of types I and III collagen s. (C) 1999 Elsevier Science B.V. All rights reserved.