title: Species-specific responses of N homeostasis and electrolyte handling to low N intake: a comparative physiological approach in a monogastric and a ruminant species.
abstract: In our former studies low crude protein (LCP) intake influenced N homeostasis and electrolyte handling in goats. We hypothesised that due to rumino-hepatic nitrogen (N) recycling adaptation of N homeostasis and adjustment of electrolyte handling to LCP intake differs between goats and monogastric animals. Therefore, an experiment similar to that with goats was conducted with rats. Two feeding groups received a diet either containing 20 or 8 % crude protein (as fed basis) for 5 weeks and intake and excretion of N, calcium (Ca) and phosphorus (P) were determined. To detect systemic and endocrine adaptation to LCP intake plasma concentrations of urea, Ca, phosphate (Pi), insulin-like growth factor 1 (IGF-1), 1,25-dihydroxyvitamin D3 (calcitriol), parathyroid hormone (PTH) and cross-linked telopeptide of type I collagen (CTX) were measured. Adjustment of renal electrolyte transport was assessed by detecting protein expression of key proteins of renal Pi transport. All data were compared with the data of the goat experiment. LCP intake decreased plasma urea concentration stronger in goats than in rats. In both species urinary N excretion declined, but faecal N excretion decreased in goats only. Furthermore, in goats urinary Ca excretion decreased, but in rats urinary Ca concentration increased. Decreased plasma IGF-1 and calcitriol concentrations were found in goats only. Thus, renal Ca excretion appears to be a common target in adaptation of electrolyte homeostasis in both species, but is regulated differently.
authors.affiliation: Department of Physiology, University of Veterinary Medicine Hannover, Bischofsholer Damm 15/102, 30173, Hannover, Germany, svenja.starke@tiho-hannover.de.
authors.forename: S
authors.initials: S
authors.lastname: Starke
authors.forename: C
authors.initials: C
authors.lastname: Cox
authors.forename: K-H
authors.initials: KH
authors.lastname: Südekum
authors.forename: K
authors.initials: K
authors.lastname: Huber
mesh_terms: D000818:Animals; D002117:Calcitriol / Q000097:blood; D002118:Calcium / Q000097:blood / Q000652:urine*; D004044:Dietary Proteins / Q000494:pharmacology*; D004573:Electrolytes / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D006041:Goats / Q000378:metabolism*; D006706:Homeostasis; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000652:urine*; D051381:Rats / Q000378:metabolism*; D017208:Rats, Wistar; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000378:metabolism; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa / Q000378:metabolism; D013045:Species Specificity
chemical_list: D004044:Dietary Proteins; D004573:Electrolytes; D010281:Parathyroid Hormone; D044168:Receptor, Parathyroid Hormone, Type 1; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa; D010758:Phosphorus; D007334:Insulin-Like Growth Factor I; D048049:Extracellular Signal-Regulated MAP Kinases; D002117:Calcitriol; D009584:Nitrogen; D002118:Calcium