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Calpains are ubiquitous neutral cysteine proteases. Although their physiological role has yet to be clarified, calpains seem to be involved in the expression of cell adhesion molecules. Therefore, we hypothesized that a selective calpain inhibitor could attenuate polymorphonuclear (PMN) leukocyte-induced myocardial ischemia-reperfusion (I/R) injury. We examined the effects of the calpain inhibitor Z-Leu-Leu-CHO in isolated ischemic (20 min) and reperfused (45 min) rat hearts perfused with PMNs. Z-Leu-Leu-CHO (10 and 20 [micro]M, respectively) significantly improved left ventricular developed pressure (LVDP) (P < 0.01) and the maximal rate of development of LVDP (P < 0.01) compared with I/R hearts perfused without Z-Leu-Leu-CHO. In addition, Z-Leu-Leu-CHO significantly reduced PMN adherence to the vascular endothelium and subsequent infiltration into the postischemic myocardium (P < 0.01). Moreover, Z-Leu-Leu-CHO significantly inhibited expression of P-selectin on the rat coronary microvascular endothelium (P < 0.01). These results provide evidence that Z-Leu-Leu-CHO significantly attenuates PMN-mediated I/R injury in the isolated perfused rat heart to a significant extent via downregulation of P-selectin expression. cardiac performance; P-selectin; left ventricular developed pressure; polymorphonuclear leukocyte infiltration

The possibility that nitric oxide (NO) functions as a protective agent in splanchnic ischemia-reperfusion and other kinds of acute intestinal inflammation was investigated. Findings showed that acute intestinal inflammation causes an early and severe decline in endothelium-derived NO, administration of exogenous NO, NO donors or NO precursors alleviates acute intestinal inflammation, blockade of NO synthase (NOS) or gene deletion of NOS aggravates intestinal inflammation, and there are a number of signaling processes that may mediate the protective function of NO.

A study was conducted to analyze the time course of events associated in splanchnic artery occlusion and reperfusion (SAO/R). Results showed endothelial dysfunction as an early event in the pathophysiology of SAO/R. The endothelial dysfunction further supported increases in the surface expression of P-selectin and adherence of neutrophils to endothelium supporting the accumulation of neutrophil in the splanchnic viscera.

Research was conducted to examine the mechanisms of cardioprotection by peroxynitrite (ONOO-) in myocardial ischemia and reperfusion (MI/R) injury. Dose-response relationship of infusion of different concentrations of ONOO- was investigated in a feline model of myocardial ischemia-reperfusion. Results indicate that maximally achievable concentrations of ONOO- may be cardioprotective while concentrations of ONOO- above these levels may have detrimental effects in the setting of MI/R injury.

The murine traumatic shock model was used to evaluate the effect of heparinase III, an enzyme that selectively cleaves heparan sulfate, on various parameters involved in traumatic shock and on the interaction between leukocytes and the mesenteric capillary endothelium. Results reveal that heparinase III improves survival time and endothelial function and reduces myeloperoxidase activity. Further, there is significant inhibition of leukocyte-endothelial cell interaction after heparinase III treatment.

Three different stable lipoxin [A.sub.4] (LX[A.sub.4]) analogs (i.e., 16-phenoxy-LX[A.sub.4]-Me, 15-cyclohexyl-LX[A.sub.4]-Me, and 15-R/S-methyl-LX[A.sub.4]-Me) were studied for their ability to modulate leukocyte-endothelial cell interactions in the rat mesenteric microvasculature. Superfusion of the rat mesentery with 50 [[micro]mol]/liter [N.sup.G]-nitro-L-arginine methyl ester (LNAME) caused a significant, time-dependent increase in leukocyte rolling (56 [+ or -] 8 cells/min; P < 0.01 vs. control) and leukocyte adherence (12.5 [+ or -] 1.2 cells/100 [[micro]meter] length of venule; P < 0.01 vs. control) after 120 min of superfusion. Concomitant superfusion of the rat mesentery with 10 nmol/liter of each of three lipoxin analogs consistently and markedly attenuated L-NAME-induced leukocyte rolling to 10 [+ or -] 4 (P < 0.01), 4 [+ or -] 1 (P < 0.01), and 32 [+ or -] 7 (P < 0.05) cells/min, and adherence to 4 [+ or -] 0.8 (P < 0.01), 1.1 [+ or -] 0.4 (P < 0.01), and 7 [+ or -] 0.7 (P < 0.05) cells/100 [[micro]meter] length of venule (16-phenoxyLX[A.sub.4]-Me, 15-cyclohexyl-LX[A.sub.4]-Me, and 15-R/S- methyi-LX[A.sub.4]Me, respectively). No alterations of systemic blood pressure or mesenteric venular shear rates were observed in any group. Immunohistochemical up-regulation of P-selectin expression on intestinal venular endothelium was significantly increased (P < 0.01) after exposure to L-NAME, and this was significantly attenuated by these lipoxin analogs (P < 0.01). Thus, in vivo superfusion of the rat mesentery with stable lipoxin analogs at 10 nmol/liter reduces L-NAME-induced leukocyte rolling and adherence in the mesenteric rat microvasculature by attenuating P-selectin expression. This anti-inflammatory mechanism may represent a novel and potent regulatory action of lipoxins on the immune system.

The regulation of P-selectin expression in human endothelial cells by nitric oxide (NO) was analyzed to determine whether NO exerts a physiological regulation of P-selectin messenger RNA expression. The study utilized cell cultures and RNA extraction analysis. Results of the analysis revealed that the increased P-selectin mRNA expression induced by synthase inhibitor NG-nitro-L-arganine methyl ester was paralleled by an increase in P-selectin protein synthesis.

The effects of lysophosphatidylcholine (LPC) on leukocyte rolling and adhesion as analyzed via intravital microscopy in rat mesenteric microvasculature. Leukocyte rolling and adherence in rat mesenteric microvasculature was enhanced by LPC superfusion. The effects of LPC in rodent mesenteric microvasculature also involved rapid LPC-induced elevations in the expression of P-selectin and intercellular adhesion molecule-1 (ICAM-1).

The role of a novel recombinant serpin, LEX-032, in anti-polymorphonuclear leukocyte (PMN) activity in response to vascular and cardiac cell injury after myocardial ischemia and reperfusion (MI/R) was investigated. Cats treated with LEX-032 showed reduced cardiac necrosis after MI/R as compared to control. Cats treated with acetylcholine following treatment with LEX-032 showed normal endothelial function. LEX-032 was also observed to significantly reduce PMN adherence to the coronary vascular endothelium. It was concluded that LEX-032 protects the host by reducing PMN-related injury.

Nitric oxide participates in vascular cell proliferation by stimulating endothelial cells and restraining the smooth muscle cell proliferation. The continuous intravenous administration of an NO donor, CAS-1609, considerably enhances the endothelium-dependent vasorelaxation and endothelial regeneration, and restricts the neointimal thickening during rat carotid artery injury.

N,N,N-trimethylsphingosine (TMS), a synthetic derivative of shingosine,decreases the interaction of polymorphonuclear neutrophils (PMNs) with the endothelium and protects the heart muscles during ischemia and reperfusion. The administration of TMS before reperfusion in feline cells decreases necrosis in the myocardial cells, the activity of cardiac myeloperoxidase and the adherence of PMNs to the endothelium, while increasing the activity of P-selectin. The relaxation of the coronary arterial rings by acetylcholine, which is dependent of endothelium, is unaffected in the TMS treated cells.

Sialyl Lewis(x)-containing oligosaccharide (SLe(x)-OS) in a rat model of traumatic shock increases the survival time from 85 plus or minus 15 min to 198 plus or minus 29 min and reduces the ideal myeloperoxidase activity and deposition of plasma-free amino-nitrogen. SLe(x)-OS also preserves the endothelium-dependent ring relaxation to acetylcholine in the superior mesentric artery and blocks the adherence of unstimulated human polymorphonuclear neutrophil to trauma-activated superior mesentric artery endothelium. Thus, SLe(x)-OS has beneficial effects in the traumatic shock states.

Intravital microscopic studies show that splanchnic artery ischemia and reperfusion (SAO/R) in rats increases the leukocyte-endothelial interaction in intestinal venules. Addition of exogenous NO donor S-nitroso-N-acetylpenicillamine (SNAP) decreases the leukocyte-endothelial interaction and plasma proteolysis. SNAP pretreatment decreases the SAO/R-induced P-selectin expression. Immunohistochemical data show that altering the leukocyte-endothelial interaction by NO proceeds through the endothelial adhesion molecule P-selectin.

The use MAb PB 1.3, a P-selectin-neutralizing monoclonal antibody, allows detection of the function of P-selectin in leukocyte-endothelium reaction following reperfusion and splanchnic arterial occlusion in pentobarbital-anesthetized rats. P-selectin is involved in accumulation of leukocytes following splanchnic ischemia-reperfusion. MAb PB1.3 reduces the polymorphonuclear leukocyte accumulation in small ischemic-reperfused bowel.

Studies on the role of a novel bradykinin receptor antagonist reveal that bradykinin is crucial in tissue injury-accompanying traumatic shock. The antagonist CP-0127 protects the tissue from the injury effects, possibly by inhibiting neutrophil-endothelial interaction and the consequent protection of vascular endothelial function.

Studies on rat cardiac myocytes reveal that they are susceptible to injury by neutrophil-released mediators such as elastase on exposure to hypoxia-reoxygenation. Such myocytes are also vulnerable to polymorphonuclear leukocyte-induced damage. The results validate the theory that neutrophils cause myocardial injury.

The effects of transforming growth factor beta1 (TGF-beta1) in a feline model of myocardial ischemia and reperfusion were studied. It was demonstrated that a cardioprotective effect of TGF-beta1 occurs on reperfusion injury following myocardial ischemia. The mechanism of this cytoprotective effect appears to be the endothelial preservation by TGF-beta1 inhibiting circulating neutrophils from adhering to the endothelium.

Mediation of Cardioprotection by Transforming Growth Factor--β M YOCARDIAL ISCHEMIA AND REPERFUSION involves a critical sustained reduction in coronary flow followed by restoration of flow to the ischemic region of [...]