Interruption of endothelin signaling modifies membrane type 1 matrix metalloproteinase activity during ischemia and reperfusion

1 Division of Cardiothoracic Surgery, Medical University of South Carolina, Charleston; and 2 The Ralph H. Johnson Veteran's Affairs Medical Center, Charleston, South Carolina Submitted 7 August 2007 ; accepted in final form 4 December 2007 The matrix metalloproteinases (MMPs), in particular, membrane type 1 MMP (MT1-MMP), are increased in the context of myocardial ischemia and reperfusion (I/R) and likely contribute to myocardial dysfunction. One potential upstream induction mechanism for MT1-MMP is endothelin (ET) release and subsequent protein kinase C (PKC) activation. Modulation of ET and PKC signaling with respect to MT1-MMP activity with I/R has yet to be explored. Accordingly, this study examined in vivo MT1-MMP activation during I/R following modification of ET signaling and PKC activation. With the use of a novel fluorogenic microdialysis system, myocardial interstitial MT1-MMP activity was measured in pigs (30 kg; n = 9) during I/R (90 min I/120 min R). Local ET A receptor antagonism (BQ-123, 1 µM) and PKC inhibition (chelerythrine, 1 µM) were performed in parallel microdialysis probes. MT1-MMP activity was increased during I/R by 122 ± 10% ( P < 0.05) and was unchanged from baseline with ET antagonism and/or PKC inhibition. Selective PKC isoform induction occurred such that PKC-βII increased by 198 ± 31% ( P < 0.05). MT1-MMP phosphothreonine, a putative PKC phosphorylation site, was increased by 121 ± 8% ( P < 0.05) in the I/R region. These studies demonstrate for the first time that increased interstitial MT1-MMP activity during I/R is a result of the ET/PKC pathway and may be due to enhanced phosphorylation of MT1-MMP. These findings identify multiple potential targets for modulating a local proteolytic pathway operative during I/R. myocardial interstitium; microdialysis; protein kinase C; phosphorylation; ischemia-reperfusion Address for reprint requests and other correspondence: F. G. Spinale, Cardiothoracic Surgery, Strom Thurmond Research Bldg., 114 Doughty St., Rm. 625, Medical Univ. of South Carolina, Charleston, SC 29403 (e-mail: wilburnm{at}musc.edu )