title: Blood flow in endogenous and transplanted pancreatic islets in anesthetized rats: effects of lactate and pyruvate.
abstract: OBJECTIVE
  The objective of this study was to evaluate the effects of exogenously administered lactate and pyruvate on blood perfusion in endogenous and transplanted islets.
  
  
  METHODS
  Anesthetized Wistar-Furth rats were given lactate or pyruvate intravenously, and regional blood perfusion was studied 3 or 30 minutes later with a microsphere technique. Separate rats received a 30-minute infusion of pyruvate or lactate into the portal vein before blood flow measurements. We also administered these substances to islet-implanted rats 4 weeks after transplantation and measured graft blood flow with laser Doppler flowmetry. The expression of monocarboxylate transporter 1 and lactate dehydrogenase A was analyzed.
  
  
  RESULTS
  The expression of monocarboxylate transporter 1 and lactate dehydrogenase A was markedly up-regulated in transplanted as compared with endogenous islets. Administration of pyruvate, but not lactate, increased mesenteric blood flow after 3 minutes. Pyruvate decreased mesenteric blood flow after 30 minutes, whereas lactate decreased only islet blood flow. These responses were absent in transplanted animals. A continuous intraportal infusion of lactate or pyruvate increased selectively islet blood flow but did not affect blood perfusion of transplanted islets.
  
  
  CONCLUSIONS
  Lactate and pyruvate affect islet blood flow through effects mediated by interactions between the liver and the nervous system. Such a response can help adjust the release of islet hormones during excess substrate concentrations.
authors.affiliation: Departments of Medical Cell Biology, Uppsala University, Uppsala, Sweden. andreea.barbu@medsci.uu.se
authors.forename: Andreea
authors.initials: A
authors.lastname: Barbu
authors.forename: Åsa
authors.initials: Å
authors.lastname: Johansson
authors.forename: Birgitta
authors.initials: B
authors.lastname: Bodin
authors.forename: Örjan
authors.initials: Ö
authors.lastname: Källskog
authors.forename: Per-Ola
authors.initials: PO
authors.lastname: Carlsson
authors.forename: Monica
authors.initials: M
authors.lastname: Sandberg
authors.forename: Joey Lau
authors.initials: JL
authors.lastname: Börjesson
authors.forename: Leif
authors.initials: L
authors.lastname: Jansson
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007515:Islets of Langerhans / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism; D016381:Islets of Langerhans Transplantation; D007527:Isoenzymes / Q000096:biosynthesis; D007770:L-Lactate Dehydrogenase / Q000096:biosynthesis; D000080864:Lactate Dehydrogenase 5; D019344:Lactic Acid / Q000008:administration & dosage*; D008297:Male; D008643:Mesentery / Q000098:blood supply / Q000187:drug effects; D008863:Microspheres; D027501:Monocarboxylic Acid Transporters / Q000096:biosynthesis; D019289:Pyruvic Acid / Q000008:administration & dosage*; D051381:Rats; D011920:Rats, Inbred WF; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D027981:Symporters / Q000096:biosynthesis; D015854:Up-Regulation; D000099233:Monocarboxylate Transport Protein 1
chemical_list: D001786:Blood Glucose; D007328:Insulin; D007527:Isoenzymes; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; D019344:Lactic Acid; D027501:Monocarboxylic Acid Transporters; D019289:Pyruvic Acid; D027981:Symporters; D000099233:Monocarboxylate Transport Protein 1