Role of renal nitric oxide synthase in diabetic kidney disease during the chronic phase of diabetes.

Background: Several studies have suggested that an early increase in renal nitric oxide (NO) production or activity mediates pathophysiologic and morphologic changes in diabetic nephropathy. To evaluate the role of NO in developing diabetic kidney disease, we studied the NO system in streptozotocin (STZ)-induced diabetic rats for a period of 8 weeks.

Methods: Control rats, STZ-induced diabetic rats, and STZ-induced diabetic rats treated with insulin were monitored and sacrificed at 1, 2, and 8 weeks.

Increased expression of endothelin-converting enzyme-1c isoform in response to high glucose levels in endothelial cells.

Endothelin-1 (ET-1) is both a potent vasoconstrictor and mitogenic factor that has been implicated as a cause of the micro- and macrovascular complications of diabetes mellitus. The pathway by which the high-glucose environment of diabetes mediates increased levels of endothelins has not been completely elucidated but appears to involve endothelin-converting enzyme (ECE-1), which converts inactive big ET-1 to active ET-1 peptide. To determine the effect of high glucose concentrations on the expression of ECE-1, hybrid endothelial cells (EA.

Renal nitric oxide production during the early phase of experimental diabetes mellitus.

Background: Diabetic nephropathy (DN) is characterized by hyperfiltration and hypertrophy in experimental models of diabetes mellitus (DM). Several studies have demonstrated that the pathophysiologic and morphologic changes in DN are mediated by either an increase or decrease in renal nitric oxide (NO) production and/or activity. The goal of the present study was to determine the effects that the early diabetic state has on NO production in the kidney of rats with streptozotocin-induced DM.

Time course of lipopolysaccharide-induced nitric oxide synthase mRNA expression in rat glomeruli.

The decrease in glomerular filtration rate that is characteristic of sepsis has been shown to result from the local glomerular inhibition of endothelial nitric oxide synthase (NOS) by nitric oxide (NO) generated from the inducible isoform of NOS (iNOS). iNOS activation depends on de novo synthesis of both RNA and protein. Therefore it is assumed that several hours are required for its full activation.

Stable and temperature-sensitive transformation of baby rat kidney cells by SV40 suppresses expression of membrane dipeptidase.

Membrane dipeptidase (MDP) is a zinc metalloenzyme located in the lungs and on the brush border membranes of the kidney and intestine. The gene for MDP (also termed DPEP1) is both frequently lost in Wilm's tumours and is located on human chromosome 16q24.3, a region of the genome known to contain a tumour suppressor gene(s).

Identification by site-directed mutagenesis of three essential histidine residues in membrane dipeptidase, a novel mammalian zinc peptidase.

Membrane dipeptidase (EC 3.4.13.

Site-directed mutagenesis of conserved cysteine residues in porcine membrane dipeptidase. Cys 361 alone is involved in disulfide-linked dimerization.

Membrane dipeptidase (EC 3.4.13.

The renal membrane dipeptidase (dehydropeptidase I) inhibitor, cilastatin, inhibits the bacterial metallo-beta-lactamase enzyme CphA.

The Aeromonas hydrophila AE036 chromosome contains a cphA gene encoding a metallo-beta-lactamase which is highly active against carbapenem antibiotics such as imipenem. Here we show that the cphA gene product shares inhibitory similarities with a mammalian zinc peptidase, membrane dipeptidase (MDP; dehydropeptidase I). Both enzymes are able to hydrolyze imipenem and are inhibited by cilastatin.

Directed mutagenesis of pig renal membrane dipeptidase. His219 is critical but the DHXXH motif is not essential for zinc binding or catalytic activity.

Pig renal membrane dipeptidase cDNA has been expressed in COS-1 cells. Directed mutagenesis was used to investigate the roles of some conserved histidyl and aspartyl residues. Mutation of His219 to Arg, Lys or Leu results in complete abolition of enzyme activity, although the mutants are expressed at the cell-surface.

Expression of a cloned gamma-aminobutyric acid transporter in mammalian cells.

The cDNA clone GAT-1, which encodes a Na(+)- and Cl(-)-coupled GABA transporter from rat brain, has been expressed in mammalian cells using three different systems: (1) transient expression upon transfection of mouse Ltk- cells with a eukaryotic expression vector containing GAT-1; (2) stable expression in L-cells transfected with the same vector; (3) transfection of HeLa cells infected with a recombinant vaccinia virus expressing T7 RNA polymerase. Similar results both qualitatively and quantitatively were obtained with all systems. The GABA transporter expressed in HeLa and L-cells retains all the properties described previously for GABA transport into synaptosomes and synaptic plasma membrane vesicles.

Cloning and expression of a rat brain GABA transporter.

A complementary DNA clone (designated GAT-1) encoding a transporter for the neurotransmitter gamma-aminobutyric acid (GABA) has been isolated from rat brain, and its functional properties have been examined in Xenopus oocytes. Oocytes injected with GAT-1 synthetic messenger RNA accumulated [3H]GABA to levels above control values. The transporter encoded by GAT-1 has a high affinity for GABA, is sodium-and chloride-dependent, and is pharmacologically similar to neuronal GABA transporters.

Structural and functional studies on the sodium- and chloride-coupled gamma-aminobutyric acid transporter: deglycosylation and limited proteolysis.

The sodium- and chloride-coupled gamma-aminobutyric transporter, an 80-kDa glycoprotein, has been subjected to deglycosylation and limited proteolysis. The treatment of the 80-kDa band with endoglycosidase F results in its disappearance and reveals the presence of a polypeptide with an apparent molecular mass of about 60 kDa, which is devoid of 125I-labeled wheat germ agglutinin binding activity but is nevertheless recognized by the antibodies against the 80-kDa band. Upon limited proteolysis with papain or Pronase, the 80-kDa band was degraded to one with an apparent molecular mass of about 60 kDa.

gamma-Aminobutyric acid transport in reconstituted preparations from rat brain: coupled sodium and chloride fluxes.

Transport of gamma-aminobutyric acid (GABA) is electrogenic and completely depends on the presence of both sodium and chloride ions. These ions appear to be cotransported with gamma-aminobutyric acid through its transporter [reviewed in Kanner, B. I.