cgs-35066 and Subarachnoid-Hemorrhage

Endothelin converting Enzyme-1 (ECE-1) is essential for the production of Endothelin-1 (ET-1), which is associated with vasospasm following subarachnoid hemorrhage (SAH). We have previously demonstrated the presence of a catalytically active soluble form of ECE-1 in the media of endothelial cells. We aimed to determine if this form of ECE-1 exists in vivo, in cerebrospinal fluid (CSF) of SAH patients. We examined CSF taken from SAH subjects for the presence of soluble ECE-1 using a bradykinin based quenched fluorescent substrate assay. We obtained further confirmation by characterizing the CSF mediated cleavage products of BigET-1 and BigET₁₈₋₃₄ (6 μg/ml) using mass spectrometry. The specificity of cleavage was confirmed using the ECE-1 inhibitor CGS35066 5 nmol/L. SAH CSF samples had mean ECE-1 activity of 0.127 ± 0.037 μmols of substrate cleaved/μl of CSF/24 h. The C-terminal peptides generated upon the cleavage of BigET-1 and BigET₁₈₋₃₄ were detected 48 h after incubation of these substrates with CSF. Cleavage of these substrates was inhibited by CGS35066. Results of Western blots also produced strong evidence for the presence of truncated soluble ECE-1 in CSF. These results strongly suggest the presence of a truncated but catalytically active form of ECE-1 in the CSF of SAH subjects. Further studies are necessary to determine the biological significance of soluble ECE-1 in CSF of SAH subjects, including an association with vasospasm after SAH.

Topics: Aspartic Acid Endopeptidases; Benzofurans; Bradykinin; Endothelin-1; Endothelin-Converting Enzymes; Enzyme Inhibitors; Humans; Hydrocephalus; Mass Spectrometry; Metalloendopeptidases; Organophosphonates; Subarachnoid Hemorrhage

Endothelin-1, a potent vasoconstrictive peptide, has been implicated in the pathogenesis of cerebral vasospasm following subarachnoid hemorrhage (SAH). The goal of this study was to evaluate the effect of continuous intravenous infusion of a highly selective endothelin-converting enzyme-1 inhibitor, CGS 35066, on the prevention and reversal of cerebral vasospasm following SAH. New Zealand white rabbits were subjected to SAH by injecting autologous arterial blood into the cisterna magna. Infusion of CGS 35066 at dosages of 1, 3, or 10 mg/kg/ day was initiated either 1 hr and 24 hrs later in the prevention and reversal protocols, respectively. Animals were sacrificed by perfusion-fixation 48 hrs after SAH induction. The cross-sectional areas of basilar arteries were measured using computer-assisted videomicroscopy. Ultrastructural changes in basilar arteries were determined using electron microscopy. CGS 35066 significantly prevented and reversed the arterial narrowing after SAH in all three groups. The mean cross-sectional areas of arteries from animals in both the prevention and reversal protocol groups that received 10 mg/kg/day of CGS 35066 did not differ significantly from those of the healthy controls. Histological studies of the basilar artery in the 10 mg/kg/day treatment group did not show pathomorphological changes, such as corrugation of the endothelium seen at 2 days after SAH induction or vacuole formation in the endothelial cells noted in the vehicle-treated SAH group. These findings suggest that CGS 35066 is a promising therapeutic agent for the prevention and reversal of cerebral vasospasm after SAH. It also prevents the pathological changes in vascular walls due to SAH.

Topics: Animals; Basilar Artery; Benzofurans; Infusions, Intravenous; Male; Organophosphonates; Protease Inhibitors; Rabbits; Subarachnoid Hemorrhage; Vasospasm, Intracranial

CGS 26303, a dual inhibitor of endothelin-converting enzyme-1 (ECE-1) and neutral endopeptidase 24.11, was previously shown to prevent and reverse vasospasm in an experimental model of subarachnoid hemorrhage (SAH). However, reversal of the vasospastic response was not very efficacious. This study was designed to examine the effects of a highly selective ECE-1 inhibitor, CGS 35066, on SAH-induced cerbrovasospasm. Experimental SAH was induced in New Zealand white rabbits by injecting autogenous blood into cisterna magna and CGS 35066 was injected i.v. twice daily, either at 1 h (prevention protocol) or 24 h (reversal protocol) after SAH. Treatment with CGS 35066 significantly attenuated basilar arterial narrowing at a dose of 1 mg/kg in both protocols. These findings provide support for the use of selective ECE-1 inhibitors for the treatment of SAH-induced vasospasm even after the process of arterial narrowing has begun.

Topics: Animals; Aspartic Acid Endopeptidases; Basilar Artery; Benzofurans; Dose-Response Relationship, Drug; Drug Administration Schedule; Endothelin-Converting Enzymes; Enzyme Inhibitors; Injections, Intravenous; Male; Metalloendopeptidases; Organophosphonates; Rabbits; Subarachnoid Hemorrhage; Vasospasm, Intracranial