Calpain system and its involvement in myocardial ischemia and reperfusion injury.

Calpains are ubiquitous non-lysosomal Ca(2+)-dependent cysteine proteases also present in myocardial cytosol and mitochondria. Numerous experimental studies reveal an essential role of the calpain system in myocardial injury during ischemia, reperfusion and postischemic structural remodelling. The increasing Ca(2+)-content and Ca(2+)-overload in myocardial cytosol and mitochondria during ischemia and reperfusion causes an activation of calpains.

Using a Caesalpinia echinata Lam. protease inhibitor as a tool for studying the roles of neutrophil elastase, cathepsin G and proteinase 3 in pulmonary edema.

Acute lung injury (ALI) is characterized by neutrophil infiltration and the release of proteases, mainly elastase (NE), cathepsin G (Cat G) and proteinase 3 (PR3), which can be controlled by specific endogenous inhibitors. However, inhibitors of these proteases have been isolated from different sources, including plants. For this study, CeEI, or Caesalpinia echinata elastase inhibitor, was purified from C.

Reduction of myocardial infarction by postischemic administration of the calpain inhibitor A-705253 in comparison to the Na(+)/H(+) exchange inhibitor Cariporide in isolated perfused rabbit hearts.

The calpain inhibitor A-705253 and the Na(+)/H(+)-exchange inhibitor Cariporide were studied in isolated perfused rabbit hearts subjected to 60 min occlusion of the ramus interventricularis of the left coronary artery (below the origin of the first diagonal branch), followed by 120 min of reperfusion. The inhibitors were added to the perfusion fluid solely or in combination at the beginning of reperfusion. Hemodynamic monitoring and biochemical analysis of perfusion fluid from the coronary outflow were performed.

Calpain inhibition reduces infarct size and improves global hemodynamics and left ventricular contractility in a porcine myocardial ischemia/reperfusion model.

Calpains, a family of Ca2+-dependent cysteine proteases, are activated during myocardial ischemia and reperfusion. This study investigates the cardioprotective effects of calpain inhibition on infarct size and global hemodynamics in an ischemia/reperfusion model in pigs, using the calpain inhibitor A-705253. The left anterior descending coronary artery was occluded for 45 min and reperfused for 6 h.

Reduction of myocardial infarction by calpain inhibitors A-705239 and A-705253 in isolated perfused rabbit hearts.

Two novel calpain inhibitors (A-705239 and A-705253) were studied in isolated perfused rabbit hearts subjected to 60-min occlusion of the ramus interventricularis of the left coronary artery (below the origin of the first diagonal branch), followed by 120 min of reperfusion. The inhibitors were added to the perfusion fluid in various final concentrations from the beginning of the experiments before the coronary artery was blocked. Hemodynamic monitoring and biochemical analysis of perfusion fluid from the coronary outflow were carried out.

Visualisation of tissue kallikrein, kininogen and kinin receptors in human skin following trauma and in dermal diseases.

During dermal injury and inflammation the serine proteases kallikreins cleave endogenous, multifunctional substrates (kininogens) to form bradykinin and kallidin. The actions of kinins are mediated by preferential binding to constitutively expressed kinin-B2 receptors or inducible kinin-B1 receptors. A feature of the kinin-B1 receptors is that they show low levels of expression, but are distinctly upregulated following tissue injury and inflammation.

A novel water-soluble and cell-permeable calpain inhibitor protects myocardial and mitochondrial function in postischemic reperfusion.

The effects of the novel calpain inhibitor A-705239 were studied in isolated perfused rabbit hearts subjected to 45 min of global ischemia, followed by 60 min of reperfusion. During 15 min of perfusion the inhibitor accumulated in myocardial tissue up to 16 times the concentration in the perfusate. Almost complete recovery and survival of heart function (90%) was seen with an inhibitor concentration of 10(-8) M in the perfusion fluid when the compound was administered prior to ischemia.

Effect of plant Kunitz inhibitors from Bauhinia bauhinioides and Bauhinia rufa on pulmonary edema caused by activated neutrophils.

Mediators released from polymorphonuclear neutrophils, in particular elastase, are known to induce acute edematous lung injury. In this study we show that the pulmonary edema in isolated perfused rabbit lungs caused by activated neutrophils via release of elastase is significantly decreased by the Kunitz-type Inhibitor BbCI (10(-5) M) from Bauhinia bauhinoides to the same degree as by eglin C (10(-5) M) from Hirudo medicinalis, which was used as a reference. The highly homologous proteinase inhibitor BrPI (10(-5) M) from Bauhinia rufa, however, did not reduce edema formation.

Impact of endothelin-1 in endotoxin-induced pulmonary vascular reactions.

Objectives: Elevated endothelin-1 (ET-1) levels have been detected during sepsis. The aim of the study was to examine the role of thromboxane A2 (TXA2) and ET-1 in pulmonary vascular reactions after endotoxin (LPS) challenge.

Design: Prospective experimental study in rabbits.

Characterization and distribution of endothelin receptors in the pulmonary circulation: investigation of isolated, perfused, and ventilated rabbit lungs.

The aim of the study was to investigate the distribution of 2 subtypes of endothelin-receptors, mediating the effects of endothelin-1 (ET-1) in the pulmonary circulation. Until now, it is still unclear, whether ET(A) receptors or ET(B) receptors or even both are localized in pulmonary vessels. The experiments were performed on 72 isolated and ventilated rabbit lungs that were perfused with a cell- and plasma-free buffer solution.

Alterations of bacterial clearance induced by propofol.

Background: The purpose of the study was to investigate the potential influence of the anaesthetic agent propofol on immune function in terms of systemic clearance and organ distribution of injected Escherichia coli in a rabbit model.

Methods: Defined numbers of E. coli (1.

Endothelin-1 and thromboxane A2 increase pulmonary vascular resistance in granulocyte-mediated lung injury.

Objective: To examine the pathophysiologic role of vasoactive eicosanoids and endothelin-1 in granulocyte-mediated effects in the pulmonary vasculature.

Design: Prospective experimental study in rabbits.

Setting: Experimental laboratory in a university teaching hospital.

The role of endothelin-1 as a mediator of the pressure response after air embolism in blood perfused lungs.

Objective: It is well known that lung embolism is associated with an increase in pulmonary vascular resistance. Since the mechanisms of pulmonary vascular reactions during embolism are still unclear, the aim of this study was to investigate the potential involvement of endothelin-1 (ET-1) and thromboxane A2 (TXA2) as mediators of the pulmonary artery pressure (PAP) increase after embolism using the selective ETA receptor antagonist LU135252 [1], the ETB receptor antagonist BQ788 [2], and the cyclooxygenase inhibitor diclofenac.

Design: Prospective experimental study in rabbits.

Effect of bradykinin B2-receptor antagonism on post-ischemic coronary reperfusion.

Isolated rabbit hearts in a modified Langendorff preparation were used to study the role of bradykinin B2-receptor antagonism on recovery from cardiac ischemia. The experiments were performed to clarify a potential risk of administrating BK-receptor antagonists in patients with coronary heart disease and patients undergoing heart surgery. The hearts were perfused in an open system at a constant pressure of 70 mm Hg and at a constant temperature of 37 degrees C with Krebs-Henseleit-buffer solution containing 6.

Effects of bradykinin, histamine and serotonin on pulmonary vascular resistance and permeability.

The effects of bradykinin, histamine and serotonin on vascular resistance and microvascular permeability were investigated in isolated cell-free perfused rabbit lungs. The capillary filtration coefficient was determined from the slope of lung weight changes over periods of venous pressure elevation before application of bradykinin (n = 6), histamine (n = 6) and serotonin (n = 6), and 5, 20 and 50 min afterwards. To prevent rapid inactivation of bradykinin by the angiotensin-converting enzyme in the pulmonary circulation, the bradykinin effects were additionally studied in the presence of the angiotensin-converting enzyme inhibitor captopril (n = 6).

Impaired bacterial clearance after activation of the complement and coagulation systems.

The aim of this study was to investigate the influence of the activation of the complement and coagulation systems on bacterial clearance and killing capacity of the reticuloendothelial system in rabbits. To enable quantification of the clearance process, defined numbers of exogenous Escherichia coli (1.3 x 10(8) colony-forming units) were injected intravenously, after complement activation with inulin-activated rabbit serum (n = 6), after complete defibrination with the snake toxin ancrod (n = 6), and in sham-operated animals (controls, n = 6).

Alteration of n-3 fatty acid composition in lung tissue after short-term infusion of fish oil emulsion attenuates inflammatory vascular reaction.

Objectives: To investigate whether modulation of the fatty acid profile can be achieved by the short-term infusion of a fish oil emulsion which may attenuate the pulmonary response to inflammatory stimulation. Changes of fatty acid pattern in-lung tissue and perfusate were analyzed and correlated with physiologic data after a 3-hr infusion of fish oil in comparison with a soybean oil preparation.

Design: Prospective, randomized, controlled trial.

Effects of N-acetylcysteine on bacterial clearance.

The aim of this study was to investigate whether the oxygen radical scavenger N-acetylcysteine (N-AC) impairs bacterial clearance, thus predisposing the host to increased risk of disease. Blood clearance of Escherichia coli and organ colonization were investigated in anaesthetized rabbits after pretreatment with N-AC (250 mg kg-1 body weight, n = 16) and in sham-operated animals (n = 12). To enable quantification of the clearance process, defined numbers of exogenous E.

Impairment of bacterial clearance induced by norepinephrine infusion in rabbits.

Objective: Purpose of the study was to investigate the potential influence of norepinephrine (NE) on immune functions in terms of systemic and organ-specific bacterial clearance in rabbits.

Design: To enable quantification of the clearance process, defined numbers of exogenous Escherichia coli (1.3 x 10(8) CFU) were injected intravenously 60 min after starting the NE infusion at a low dose (1 microgram/kg per min, n = 6), causing an increase (30 mmHg) in mean arterial pressure without affecting the oxygen uptake, and at a higher dose (7.

Influence of B2 receptor antagonists on bradykinin-induced vasodilation and edema formation in isolated rabbit hindlimbs.

In search of new possibilities to prevent acute inflammatory vascular reaction, we examined the effect of two selective B2 receptor antagonists, CP 0127 ([Bissuccimidohexane (L-Cys6)-1] and HOE 140 (D-Arg[Hyp3, Thi5, D-Tic7, Oic8]BK), on changes in perfusion pressure and on edema formation caused by bradykinin (BK) in the isolated perfused rabbit hindlimbs. CP 0127 and HOE 140 were added to the perfusion fluid 2 min prior to the first BK-administration (5 x 10(-9) mol/l). A second BK-stimulation was performed after 30 minutes.

Effect of hypertonic NaCl-starch-solution on oedema of different pathogenesis.

Small volumes of hypertonic NaCl-solutions have been proven to restore haemodynamics in hypovolemic shock patients. Topic of this study was to investigate whether bolus application of 7.5% NaCl-6.

Effects of stroma-free hemoglobin solutions on pulmonary vascular resistance and mediator release in the isolated perfused rabbit lung.

The aim of this study was to evaluate the effect of an ultrapure bovine stroma-free hemoglobin (SFH) on pulmonary vascular resistance and mediator release and to analyze potential mechanisms of action in the isolated perfused rabbit lung model. Repetitive bolus applications of small amounts of bovine SFH were examined which resulted in a reproducible acute increase of pulmonary vascular resistance of approx. 9 mmHg (controls, n = 6).

Modulation of pulmonary vascular resistance and edema formation by short-term infusion of a 10% fish oil emulsion.

Background: The aim of this study was to investigate whether the pulmonary response to inflammatory stimulation, resulting in increased vascular resistance and permeability, could be attenuated by short-term infusion of triglycerides containing omega-3 fatty acids. With the concept of altering the composition of membrane phospholipids in such a manner that stimulation resulted in the release of less vasoconstrictive and permeability-enhancing metabolites of eicosapentaenoic acid instead of those of arachidonic acid (AA), the parenteral application of a lipid emulsion prepared from fish oil (Omegavenös) was tested in comparison with a soy oil preparation (Lipovenös).

Methods: Isolated lungs from anesthetized rabbits were ventilated and recirculatingly perfused (200 ml/min) with 200 ml cell-free buffer solution to which either 2 ml saline (controls, n = 6), 2 ml Lipovenös 10% (n = 6) or 2 ml Omegavenös 10% (n = 6) were added.