Targeting the kallikrein-kinin system as a new therapeutic approach to diabetic retinopathy.

Diabetic retinopathy (DR) is a major microvascular complication of diabetes mellitus that can lead to visual impairment and blindness. There is no approved pharmacological treatment for DR; however, laser therapy, steroids and anti-VEGF agents appear to provide some benefit. Hyperglycemia, advanced glycation end products, growth factors, and elevated levels of circulating and vitreous cytokines and chemokines can all trigger an inflammatory response of the retinal vasculature.

Inflammatory hyperalgesia induced by zymosan in the plantar tissue of the rat: effect of kinin receptor antagonists.

The Randall-Selitto paradigm (maximal tolerated pressure externally applied by a mechanical device) was used to develop a rat model of localized inflammatory hyperalgesia in order to compare the analgesic effects of bradykinin (BK) B1 and B2 receptor antagonists and of a non-steroidal anti-inflammatory drug (NSAID). Intra-plantar injection of zymosan (12.5 mg per paw) induced a considerable inflammation as evidenced from gross and histological evaluation and a mechanical hyperalgesia at 6 h.

Pharmacological profile of LF 16-0687, a new potent non-peptide bradykinin B2 receptor antagonist.

LF 16-0687 (1-[[2,4-dichloro-3-[[(2,4-dimethylquinolin-8-yl)oxy] methyl]phenyl]sulfonyl]-N-[3-[[4-(aminoimethyl) phenyl] carbonylamino]propyl]-2(S)-pyrrolidinecarboxamide) has been selected from a large-scale medicinal chemistry program for further development. In competition binding studies using [3H]bradykinin (BK), LF 16-0687 bound to the human, rat and guinea-pig recombinant B2 receptor expressed in CHO cells giving K(i) values of 0.67 nM, 1.

Synthesis and characterization of bradykinin B(2) receptor agonists containing constrained dipeptide mimics.

We have previously shown that substitution of the D-Tic-Oic dipeptide by a (3S)-[amino]-5-(carbonylmethyl)-2,3-dihydro-1, 5-benzothiazepin-4(5H)-one (D-BT) moiety in the bradykinin B(2) receptor antagonist HOE 140 resulted in a full potent and selective bradykinin B(2) receptor agonist (H-DArg-Arg-Pro-Hyp-Gly-Thi-Ser-D-BT-Arg-OH, JMV1116) exhibiting a high affinity for the human receptor (K(i) 0.7 nM). In the present study, we have investigated the effects of replacement of the D-Tic-Oic moiety by various constrained dipeptide mimetics.

Design and synthesis of potent bradykinin agonists containing a benzothiazepine moiety.

A bradykinin analogue (H-Arg-Pro-Pro-Gly-Phe-Ser-D-BT-Arg-OH, 3) in which the Pro-Phe dipeptide was replaced by the (3S)[amino]-5-(carbonylmethyl)-2,3-dihydro-1, 5-benzothiazepin-4(5H)-one (D-BT) moiety has been synthesized. The same modification was performed on the potent bradykinin B(2) receptor antagonist HOE 140 (H-D-Arg-Arg-Pro-Hyp-Gly-Thi-Ser-D-Tic-Oic-Arg-OH), in which the -D-Tic-Oic- moiety was replaced by D-BT to yield H-D-Arg-Arg-Pro-Hyp-Gly-Thi-Ser-D-BT-Arg-OH, 1 (JMV1116). These compounds were examined in vitro for their binding affinity toward bradykinin B(1) and B(2) receptors as well as for their ability to interfere with bradykinin-induced contraction of both human umbilical vein and rat uterus.

Pharmacological and molecular evidence for kinin B1 receptor expression in urinary bladder of cyclophosphamide-treated rats.

1. In the present study, we developed an experimental model of cystitis induced by cyclophosphamide (CYP). In order to characterize des-Arg9-BK-induced contraction on the urinary bladder (UB) during the development of inflammation and to quantify kinin B1 receptor gene expression using a quantitative RT - PCR technique.

Pharmacological characterization of the bradykinin B2 receptor: inter-species variability and dissociation between binding and functional responses.

1. The present study addresses the differences in binding profiles and functional properties of the human and rat bradykinin (BK) B2 receptor using various kinin receptor peptide derivatives as well as the non-peptide receptor antagonists WIN 64338 (phosphonium, [[4-[[2-[[bis(cyclohexylamino)methylene]amino]-3-(2-naphtalenyl)1- oxopropyl]amino]-phenyl]-methyl]tributyl, chloride, monohydro-chloride), and FR173657 (E)-3-(6-acetamido-3-pyridyl)-N-[-N-[2,4-dichloro-3-[(2-methyl-8-quinoli nyl)oxymethyl]-phenyl]N-methylamino carbonyl methyl] acrylamide. 2.

Effects of lipid-lowering drugs on left ventricular function and exercise tolerance in dyslipidemic coronary patients.

Previous studies suggested that certain lipid-lowering drugs such as statins suppress ubiquinone, affect mitochondrial function, and may have deleterious effect on skeletal or cardiac muscles with potentially serious clinical consequences, especially in patients with established coronary heart disease and left ventricular dysfunction. In this double-blind study, we assessed the effects of 20 mg simvastatin (S, n = 32) or 200 mg micronized fenofibrate (F, n = 32, control group) on rest and exercise left ventricular function in hypercholesterolemic survivors of a previous Q-wave acute myocardial infarction. Left ventricular radionuclide imaging was performed at rest and during submaximal exercise and global and segmental (nine segment regional wall-motion score) ejection fractions were measured before treatment and 12 weeks later.

In vitro and in vivo effects of the new nonpeptide bradykinin B2 receptor antagonist, LF 16-0335C, on guinea-pig and rat kinin receptors.

Activation of the kinin-kallikrein system and stimulation of bradykinin (BK) B2 receptors are thought to play an important role in the pathophysiology of inflammation and pain. In the present study, we report the pharmacological properties of a novel nonpeptide bradykinin B2 receptor antagonist, LF 16-0335C, (1-[[3-[(2,4-dimethylquinolin-8-yl) oxymethyl]-2,4-dichloro-phenyl]sulfonyl]-2(S)-[[4-[4- (aminoiminomethyl)-phenylcarbonyl]piperazin-1-yl]carbo nyl]pyrrolidine, 2HCl). In binding studies, LF 16-0335C competed with [3H]bradykinin giving Ki values of 1.

LF 16.0335, a novel potent and selective nonpeptide antagonist of the human bradykinin B2 receptor.

1. In the present paper, we describe the in vitro pharmacological properties of LF 16.0335 (1-[[3-[(2,4-dimethylquinolin-8-yl)oxymethyl]-2,4-dichloro-p henyl]sulphonyl] -2(S) - [[4 -[4-(aminoiminomethyl)phenylcarbonyl]piperazin-1-yl]ca rbonyl]pyrrolidine), a novel and potent nonpeptide antagonist of the human bradykinin (BK) B2 receptor.

Synthesis and pharmacological evaluation of dimer derivatives of the bradykinin receptor antagonist HOE-140.

The synthesis and pharmacological evaluation of dimer derivatives of the C-terminal fragments of the potent bradykinin antagonist HOE-140, linked through their N-termini, were performed. The influence of peptide moiety length was studied using the succinyl moiety as a linker. Our attention focused on the dimer of the C-terminal tetrapeptide of HOE-140 (compound JMV 980), which displayed some inhibiting activity (IC50 = 247 nM) for bradykinin B2 receptors.

GeneUp: a program to select short PCR primer pairs that occur in multiple members of sequence lists.

A computer program is presented that selects a small set of short primer pairs for PCR to sample all the sequences in a user-specified list of mRNAs. Such primer pairs could be used to increase the probability of sampling mRNAs of particular interest in differential display and to generate simplified hybridization probes for DNA chips or arrays. The program uses simulated PCR to find pairs of primers that sample more than one sequence in the list.

Haemodynamic and cardiac effects of kinin B1 and B2 receptor stimulation in conscious instrumented dogs.

1. Mongrel dogs were chronically instrumented with an intra-aortic catheter, a Königsberg intraventricular pressure transducer and a Döppler flow probe around the left coronary artery. After ganglionic blockade with hexamethonium, the cardiovascular effects of bradykinin B1 and B2 receptor agonists, des-Arg9-bradykinin and bradykinin (BK), were investigated in the presence and absence of specific antagonists.

Characterisation of bradykinin receptors from juvenile pig coronary artery.

Coronary artery rings from juvenile male farm pigs were incubated for 6 h and precontracted with U46619. The rings relaxed in response to des-Arg9-bradykinin (pD2, 7.78 +/- 0.

Quantitative image analysis of cell proliferation after balloon catheter injury in the rabbit carotid artery.

Objective: To perform color image analysis to assess the course of morphometric and proliferative changes in the intima and media of rabbit carotid arteries following balloon injury.

Study Design: Proliferating smooth muscle cells were labeled with proliferating cell nuclear antigen and vizualized by immunohistochemical staining of histologic sections. Morphometry was performed on histologic cross-sections of injured arteries stained with hematoxylin.

Reduction of intimal hyperplasia by naroparcil, a 4-methylumbelliferyl beta-D-xyloside analogue, after arterial injury in the hypercholesterolemic rabbit.

4-Methylumbelliferyl beta-D-xylosides (beta-D-xylosides) inhibit proteoglycan synthesis, and this is associated with reduced proliferation and extracellular matrix production by vascular smooth muscle cells. This study evaluated whether treatment with naroparcil, a beta-D-xyloside analogue, reduced intimal hyperplasia after arterial injury in the hypercholesterolemic rabbit. Forty-two rabbits were assigned to three groups that received either a 1% cholesterol-enriched diet (group 1, n = 15) or the same diet with added 100 mg.

Pharmacological evidence for a single bradykinin B2 receptor in the guinea-pig.

1. The present study addresses the possibility of the existence of different kinin B2 receptor subtypes in the guinea-pig by evaluating the affinity of peptide and nonpeptide receptor antagonists. For this purpose, jugular vein rings, ileum segments, lung parenchymal and trachea strips were set up in organ baths for isometric tension measurements.

The kinin B1 receptor antagonist des-Arg9-[Leu8]bradykinin: an antagonist of the angiotensin AT1 receptor which also binds to the AT2 receptor.

1. Agonists and antagonists of kinin B1 and B2 receptors were evaluated in vitro for their effects against angiotensin II (AII)-induced contractile responses in the rabbit aorta and for their binding properties to angiotensin AT1 and AT2 receptors from purified membrane of rat liver and lamb uterus respectively. 2.

Induction of kinin B1 receptor-dependent vasoconstriction following balloon catheter injury to the rabbit carotid artery.

1. Balloon catheter injury to the rabbit carotid artery damaged the endothelium and induced neointima formation over 7 days. The area of intima, expressed as a percentage of the media, was 16.

Markedly different effects on ventricular remodeling result in a decrease in inducibility of ventricular arrhythmias.

Objectives: The purpose of this study was to determine whether the type and extent of ventricular remodeling after infarction influence inducibility of ventricular arrhythmias after infarction.

Background: Although serious ventricular arrhythmias after infarction are related to ventricular dysfunction, the relation between inducibility of ventricular arrhythmias and ventricular remodeling remains incompletely understood.

Methods: Rats that survived ligation of the left anterior descending coronary artery (n = 218) were randomized to receive placebo (saline solution) or captopril or propranolol therapy and were followed up for 5 weeks.

Induction of bradykinin B1 receptor-mediated relaxation in the isolated rabbit carotid artery.

Responses to bradykinin and to the bradykinin B1 receptor agonist des-Arg9-bradykinin were studied in freshly isolated rabbit carotid artery rings and in rings after a 5-h period of incubation. In freshly isolated rings precontracted with noradrenaline, neither bradykinin nor des-Arg9-bradykinin changed the tension whereas acetylcholine relaxed the vessel in a concentration-dependent manner. After incubation, des-Arg9-bradykinin, and to a lesser extent bradykinin, produced an endothelium-dependent relaxation.

Regulation of the endothelin-1 transmembrane signaling pathway: the potential role of agonist-induced desensitization in the coronary artery of the rapid ventricular pacing-overdrive dog model of heart failure.

This study examined the potential role of ET-1 and the contribution of protein kinase C (PKC) in the desensitization of the ET-1 transmembrane signaling pathway in the left circumflex coronary artery (CCA) of a dog model of congestive heart failure (CHF). In the CCA of the rapid ventricular pacing-overdrive dog model of CHF, elevated plasma endothelin levels were associated with a decrease in the basal accumulation of inositol phosphates and ET-1 mediated activation of phosphatidylinositol (PI) turnover (P < 0.05).

Effect of a long-term treatment with lovastatin or fenofibrate on hepatic and cardiac ubiquinone levels in cardiomyopathic hamster.

This study was undertaken to determine if long-term oral administration of lovastatin (50 mg/kg per day) or fenofibrate (200 mg/kg per day) was affecting ubiquinone levels in the heart and the liver of cardiomyopathic hamsters. After 23 weeks of treatment, ubiquinone concentrations (CoQ9 + CoQ10) and ubiquinone ratio (CoQ10/CoQ9) were determined in the heart and in the liver. Our results indicate that lovastatin significantly decreased ubiquinone concentrations in the heart (-33%, P < 0.

Endothelium-dependent control of vascular tone in the rabbit kidney after ischemia and reperfusion.

We investigated the effects of renal ischemia with reperfusion on the reactivity of rabbit renal vasculature. The main renal and arcuate arteries were isolated and studied as ring preparations. In the renal artery, concentration-response curves for potassium chloride (KCl), noradrenaline (NA), serotonin (5-HT), angiotensin II (AII), acetylcholine (ACh), A23187 or sodium nitroprusside (SNP) were unaltered after ischemia and reperfusion.

Increased preproenkephalin A gene expression in the rat heart after induction of a myocardial infarction.

The expression of preproenkephalin A (ppENK) gene was investigated in the rat heart, following the onset of myocardial infarction induced by ligation of the left anterior descending coronary artery. The relative abundance of ppENK mRNA and the level of enkephalins were measured by Northern blot analysis and radioimmunoassay, respectively, in the ventricles from control-unoperated, sham-operated, and operated rats. Three hours after the surgery, a comparison between rats with infarction and sham-operated rats revealed that the relative abundance of ppENK mRNA and the level of enkephalins were increased three- to four- and two- to three-fold, respectively, in the ventricles of rats with infarction.