Adaptation of renal ammonia production in the diabetic ketoacidotic rat

Adaptation of renal ammonia production in the diabetic ketoacidotic rat. Renal ammonia production was measured in diabetic, ketoacidotic rats. Rats were made diabetic by the i.v. injection of streptozotocin (150mg/kg of body wt). They were maintained on insulin for 1 week. Ketoacidosis was induced by withdrawing insulin for 3 days. At that time, blood and kidney ketone body (D-β-hydroxybutyrate and acetoacetate) levels were markedly elevated (approx. 6mM), and plasma total carbon dioxide concentration was strongly depressed (approx. 11mM). Renal ammonia production (ammonia released into renal vein plus that excreted in the urine) was stimulated sevenfold by the diabetic ketoacidosis. In a separate study, we examined the effects of ketone bodies on renal ammonia production in ammonium-chloride-induced acidotic, nondiabetic rats. Infusion of β-hydroxybutyrate had no significant effect on either urinary ammonia excretion (at relatively constant urinary pH), total renal ammonia production, or renal glutamine extraction. In vitro studies showed that β-hydroxybutyrate (4.0mM) markedly inhibited (61%) conversion ofL-glutamine (0.6mM) to ammonia by renal cortical slices prepared from normal rats. Inhibition was greatly reduced with slices prepared from kidneys of acidotic (ammonium-chloride-induced or diabetic ketoacidosis) rats. These results indicate that (1) renal ammonia production is markedly stimulated in diabetic ketoacidosis, and (2) in contrast to findings previously obtained by others in the acidotic dog, ketone bodies do not appear to inhibit renal ammonia production in vivo and only weakly in vitro in the acidotic rat.Adaptation de la production rénale d'ammoniac chez le rat diabétique en acidocétose. La production rénale d'ammoniaque a été mesurée chez le rat diabétique en acidocétose. Les rats ont été rendus diabétiques par une injection i.v. de streptozotocine (150 mg/kg body wt) et traités par l'insuline pendant une semaine. L'acidocétose a été déclenchée par la suppresion de l'insuline pendant trois jours. A ce moment, les concentrations sanguines et rénales de corps cétoniques (D-β-hydroxybutyrate et acéto-acétate) étaient très augmentées (approximativement 6mM) et le CO2 total du plasma très abaissé (approximativement 11mM). La production rénale d'ammoniac (ammoniac de la veine rénale plus ammoniaque de l'urine) était multipliée par 7. Dans un protocole différent, nous avons étudié les effets des corps cétoniques sur la production rénale d'ammoniac chez des rats non diabétiques, en acidose parle chlorure d'ammonium. La perfusion de β-hydroxybutyrate n'a eu d'effet significatif ni sur l'excétion urinaire d'ammoniaque (à pH relativement constant), ni sur la production rénale d'ammoniac ou l'extraction rénale de la glutamine. Des études in vitro ont montré que le β-hydroxybutyrate (4,0mM) inhibe de façon importante (61%) la conversion de laL-glutamine (0,6mM) en ammoniac par les tranches de cortex de rein préparées à partir de rats normaux. L'inhibition est moindre avec des tranches préparées à partir de rats en acidose (chlorure d'ammonium ou acidocétose diabétique). Ces résultats indiquent que (1) la production rénale d'ammoniac est fortement stimulée au cours de l'acidocétose diabétique et, (2) contrairement aux résultats obtenus par d'autres chez le chien en acidose, les corps cétoniques ne paraissent pas inhiber la production rénale d'ammoniac in vivo, et seulement faiblement in vitro, chez le rat en acidose

The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia

<p>Abstract</p> <p>Background</p> <p>The different physiological repertoire of CA3 and CA1 neurons in the hippocampus, as well as their differing behaviour after noxious stimuli are ultimately based upon differences in the expressed genome. We have compared CA3 and CA1 gene expression in the uninjured brain, and after cerebral ischemia using laser microdissection (LMD), RNA amplification, and array hybridization.</p> <p>Results</p> <p>Profiling in CA1 vs. CA3 under normoxic conditions detected more than 1000 differentially expressed genes that belong to different, physiologically relevant gene ontology groups in both cell types. The comparison of each region under normoxic and ischemic conditions revealed more than 5000 ischemia-regulated genes for each individual cell type. Surprisingly, there was a high co-regulation in both regions. In the ischemic state, only about 100 genes were found to be differentially expressed in CA3 and CA1. The majority of these genes were also different in the native state. A minority of interesting genes (e.g. inhibinbetaA) displayed divergent expression preference under native and ischemic conditions with partially opposing directions of regulation in both cell types.</p> <p>Conclusion</p> <p>The differences found in two morphologically very similar cell types situated next to each other in the CNS are large providing a rational basis for physiological differences. Unexpectedly, the genomic response to ischemia is highly similar in these two neuron types, leading to a substantial attenuation of functional genomic differences in these two cell types. Also, the majority of changes that exist in the ischemic state are not generated de novo by the ischemic stimulus, but are preexistant from the genomic repertoire in the native situation. This unexpected influence of a strong noxious stimulus on cell-specific gene expression differences can be explained by the activation of a cell-type independent conserved gene-expression program. Our data generate both novel insights into the relation of the quiescent and stimulus-induced transcriptome in different cells, and provide a large dataset to the research community, both for mapping purposes, as well as for physiological and pathophysiological research.</p

The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia-4

<p><b>Copyright information:</b></p><p>Taken from "The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia"</p><p>http://www.biomedcentral.com/1471-2164/8/370</p><p>BMC Genomics 2007;8():370-370.</p><p>Published online 15 Oct 2007</p><p>PMCID:PMC2194787.</p><p></p>ischemic animals and the non-ischemic controls (means of n = 4 experiments for each region). In each of the hippocampal subregions more than 5000 genes could be identified exhibiting differential expression upon ischemia. A. 5243 differentially expressed genes were detected in the CA3 region. B. 5511 differentially expressed genes were detected in the CA1 region. Red: significantly regulated genes (p< 0.05; differentially regulated genes in blue). C, A total of 97 genes is significantly different between ischemic CA3 and ischemic CA1 regions (scatterplot; blue are significantly regulated genes p< 0.05). D, Bar graph showing the 5 most different genes with preference for CA3 or CA1 with their relative enrichment factors (prdma, pr-domain containing protein 8; Inhba, Inhibin beta A; Bok, Bcl-2 related ovarian killer; Sytl4, synaptotagmin-like 4; rbp 4, retinol binding protein 4; mpped1, metallophosphoesterase domain containing 1; mrg1, myeloid ecotropic viral integration site-related gene 1, alternative names: meis2, stra10)

The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia-6

<p><b>Copyright information:</b></p><p>Taken from "The functional genome of CA1 and CA3 neurons under native conditions and in response to ischemia"</p><p>http://www.biomedcentral.com/1471-2164/8/370</p><p>BMC Genomics 2007;8():370-370.</p><p>Published online 15 Oct 2007</p><p>PMCID:PMC2194787.</p><p></p>ull hemispheric infarcts. A, TTC-stained coronal section 24 h after induction of ischemia/hypoxia demonstrate a full hemispheric infarct which fully covers the hippocampal region. B, The cutting outlines used for Laser microdissection from coronal cryosections are demonstrated on a section stained with an antibody against NeuN and a secondary Cy3-coupled antibody. Actual Laser microdissections in the experiments were performed on Thionin-stained sections. C, Scheme showing the strategy used for detection of differentially regulated genes from amplified RNA. Samples from CA3 and CA1 regions were hybridized on two-color oligonucleotide arrays (Agilent). Direct competitive hybridizations were performed for all combinations: CA3 sham vs, CA1 sham, CA3 ischemia vs CA1 ischemia, CA3 ischemia vs CA3 sham, and CA1 ischemia vs CA1 sham. All experiments were also dye-swapped, and means of the two corresponding values used for further analyses. Arrays were statistically analyzed using linear modelling (limma, R)