HMGB1, indicating that these cells are capable of releasing HMGB1 from the nucleus. rHMGB1 stimulated SMC proliferation in a dose dependent fashion with the greatest increase of 2.5 fold detected at 1 g/ml (P .05) (Figure 1). Finally, carotid artery injury in mice with an 0.18 in wire does not result in significant IH. However, mice treated with rHMGB1 (10g) at the time of vascular injury devel- oped large neointimal lesions (Figure 2), supporting a role for HMGB1 in promoting IH. CONCLUSION: Vascular SMC release HMGB1 in response to cellular injury suggesting that injury can lead to vascular release of this danger signal. SMC respond to rHMGB1 with greatly increased proliferation and rHMGB1 induced increased IH in mice. These findings support the ability of the vasculature to release and respond to this endogenous danger signal and implicate the innate immune response in the pathogenesis of vascular disease. Fig 1: rHMGB1 stimulates SMC proliferation. Fig 2: rHMGB1 increases neointima formation in injured mouse carotid arteries. 58. CPKC INHIBITION DIFFERENTIALLY AFFECTS HY- POXIC PULMONARY VASOCONSTRICTION AND PUL- MONARY ARTERY CYTOKINE EXPRESSION. Tsai BM, Patel K, Morrell E, Wang M, Meldrum DR; Indiana University School of Medicine Introduction: Acute hypoxic pulmonary vasoconstriction may be an adaptive response to shunt blood to well oxygenated areas of lung, but hypoxia-induced inflammatory cytokine production leads to acute lung injury. We have previously shown that protein kinase C (PKC) mediates both hypoxic pulmonary vasoconstriction and in- flammatory cytokine expression from the pulmonary artery; however the effect of specific PKC isoform inhibition is currently unknown. We hypothesized that inhibition of classical PKC (cPKC) isoforms would attenuate hypoxia-induced pulmonary artery cytokine expres- sion but have no effect on hypoxic pulmonary vasoconstriction. Methods: Isometric force displacement was measured in isolated rat pulmonary artery rings (n=6/group) during hypoxia (95% N 2 /5% CO 2 ) in the presence of the nonspecific PKC inhibitor bisindolylma- leimide (BIM, 1 micromol/L), the cPKC inhibitor Go ¨ 6976 (1 micromol/L), or vehicle (DMSO, 0.001%). Following 60 minutes of hypoxia, pulmonary artery rings were analyzed for TNF and IL-1 mRNA via RT-PCR. Differences were considered significant if p0.05 by two-way ANOVA with post-hoc Bonferonni or unpaired t-test. Results: Nonspecific PKC inhibition (BIM) significantly at- tenuated hypoxic pulmonary vasoconstriction (44.59 10.52% vs. 87.06 10.91% vehicle, p0.001) and downregulated hypoxia- induced expression of pulmonary artery TNF and IL-1. Specific cPKC inhibition (Go ¨ 6976) attenuated pulmonary artery TNF and IL-1 expression, but had no effect on hypoxic pulmonary vasocon- striction (82.61 10.51% vs. 87.06 10.91% vehicle). Conclusions: These data indicate that: 1) nonspecific PKC inhibition attenuates both hypoxic pulmonary vasoconstriction and pulmonary artery cy- tokine expression; 2) classical PKC inhibition downregulates hypoxia-induced pulmonary artery TNF and IL-1 expression, but has no effect on hypoxic pulmonary vasoconstriction; and 3) hypoxic pulmonary vasoconstriction and hypoxia-induced pulmonary artery cytokine expression are independent processes. Therefore, specific cPKC inhibition may offer therapeutic benefits in the treatment of hypoxia-induced acute lung injury. 59. PROTEIN KINASE C-DELTA NEGATIVELY REGULATES MIGRATION AND PROLIFERATION OF VASCULAR SMOOTH MUSCLE CELLS THROUGH INHIBITION OF THE MITOGEN ACTIVATED PROTEIN KINASE ERK1/2. E. Ryer, B. Liu, R. Hom, K. Sakakibara, S. Trocciola, P. L. Faries, K. Kent; New York Presbyterian Hospital - Weill Medical College of Cornell University, NYC, NY. Introduction: Intimal hyperplasia is the principal cause of blood vessel restenosis following vascular intervention. Migration and pro- liferation of vascular smooth muscle cells (SMCs) are key early events in this pathologic process. In these studies, we test the hy- pothesis that the ubiquitously expressed intracellular protein, Pro- tein Kinase C -Delta (PKC), functions as a negative regulator of both SMC proliferation and migration through a mechanism involv- ing the Mitogen Activated Protein Kinase (MAPK) ERK1/2. Meth- ods: SMCs were isolated from the thoracic aorta of both PKC -/- and +/+ mice. Protein expression was assessed using Western blot- ting. In vivo PKC expression was evaluated with immunostaining following rat carotid balloon injury. Results: We first analyzed the course of PKC expression following rat carotid artery balloon injury. Beginning on day 7, there was a significant decrease in levels of PKC in the media of injured arteries, which continued to decline through day 14. Corresponding to this decrease in PKC, there was a equivalent increase in intimal hyperplasia as quantified by intima: media ratio [Figure A, n=4, (p0.05)]. These findings raise the possibility that diminished levels of PKC may contribute to the formation of intimal hyperplasia. To evaluate the effect of PKC on SMC migration and proliferation we overexpressed PKC in rat aortic SMCs using an adenovirus vector (AdPKC). This resulted in a decrease in PDGF-stimulated chemotaxis and proliferation of 44.1% and 46.4%, respectively (p0.05). We then evaluated the effect of PKC inhibition by employing SMCs from PKC knockout mice. We found a 34.7% increase in PDGF-stimulated migration of PKC -/- SMCs as compared to SMCs from PKC +/+ littermates (Figure B, p0.01). Moreover, evaluation of DNA synthesis revealed a 3.3 fold increase in basal and 28.5% increase in PDGF-stimulated pro- liferation in PKC -/- as compared to +/+ SMCs (Figure C, p0.01). Thus, PKC is a negative regulator of both SMC prolifera- tion and migration. We next evaluated the signaling pathway through which PKC produces this inhibitory effect. We studied the MAPK ERK1/2 pathway, which we have previously shown to be an activator of SMC migration and proliferation. Overexpression of PKC diminished ERK1/2 activity by 53.6% (p0.05). Inhibition of PKC by gene deletion (PKC -/- SMCs) led to a 17-fold increase in ERK1/2 activation in response to PDGF versus only a 1.5 fold induc- tion in PKC +/+ SMCs. These data demonstrate that PKC nega- 182 ASSOCIATION FOR ACADEMIC SURGERY AND SOCIETY OF UNIVERSITY SURGEONS—ABSTRACTS