Protein-mediated elevations in renal hemodynamics: existence of a hepato-renal axis?
Unlike the intestinal hyperemia which occurs following ingestion of a mixed meal, postprandial renal hemodynamic responses to food appear to be specific to protein-rich meals. Several observations have led to the proposal that following ingestion of protein (meat), a blood-borne factor(s) is released into the systemic circulation which elicits the increases in renal hemodynamics. Glucagon was initially considered as a prime hormonal candidate since the polypeptide is preferentially secreted by the endocrine pancreas in response to protein-rich meals and because glucagon elevates renal hemodynamics by selectively dilating renal afferent arterioles. However, recent data indicate that at postprandial blood levels, glucagon fails to directly mediate protein-induced renal hyperemia and hyperfiltration thus questioning the physiologic importance of glucagon on the renal vasculature. Data have accumulated indicating the importance of the liver and hepatic metabolism during protein-mediated elevations in renal hemodynamics. A hypothesis is advanced suggesting the existence and physiologic importance of a "hepato-renal axis" in mediating the postprandial increases in renal hemodynamics following ingestion of protein-rich meals. The blood-borne factor(s) mediating this response remains to be further clarified and defined.
D000596:Amino Acids / Q000502:physiology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D005502:Food; D005768:Gastrointestinal Hormones / Q000502:physiology; D005919:Glomerular Filtration Rate / Q000187:drug effects; D005934:Glucagon / Q000494:pharmacology / Q000502:physiology; D013006:Growth Hormone / Q000502:physiology; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D007668:Kidney / Q000098:blood supply* / Q000502:physiology; D008099:Liver / Q000502:physiology*; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism; D012079:Renal Circulation / Q000187:drug effects; D014664:Vasodilation
D000596:Amino Acids; D001786:Blood Glucose; D004044:Dietary Proteins; D005768:Gastrointestinal Hormones; D013006:Growth Hormone; D005934:Glucagon; D009584:Nitrogen