Renal handling of guanidino compounds in rat and rabbit.

Abstract

1. Guanidino compounds (GCs) have been quantified in different mammalian tissues such as brain, liver, muscle and kidney. The high anatomical heterogeneity of the kidney suggests that GCs could be unevenly distributed along the corticopapillary axis of the kidney in different species. 2. This study was designed to quantify twelve GCs in the different zones of rat and rabbit kidney. The kidneys were sliced and pieces of seven definite zones were weighed and homogenized for further GC extraction. GCs were determined by liquid chromatography. 3. The results indicate that: (1) GCs were unevenly distributed along rat and rabbit kidney; (2) qualitative and quantitative studies proved that each GC shows a particular distribution pattern along the corticopapillary axis for a given species; (3) in rats, alpha‐keto‐delta‐guanidinovaleric acid, guanidinosuccinic acid, creatinine (CTN), methylguanidine and to a lesser extent gamma‐guanidinobutyric acid increased steeply along the inner medulla in parallel to urea, whereas in rabbits, most of the GCs reached a plateau in the inner medulla and remained constant at this level; (4) gamma‐guanidinobutyric acid was specifically found in the rat kidney; (5) argininic acid was higher in rabbit compared with rat kidney; (6) significantly higher levels of homoarginine were found in all zones of the rat kidney compared with the rabbit kidney. 4. The results suggest that: (1) GCs are mostly localized within the nephron segments; (2) an accumulation of GCs in the inner medulla might be explained either by a recycling process or by an intracellular storage as has been reported for urea, amino acids and organic osmolytes; (3) some GCs might be synthesized in nephron segments as reported for arginine (Arg) and guanidinoacetic acid (GAA); (4) several metabolic pathways of the GCs seemed to differ between rat and rabbit; (5) except for creatine, CTN, Arg and GAA, it seems unlikely that GCs might significantly increase the intracellular osmolality.

Influence of 72% injury in one kidney on several organs involved in guanidino compound metabolism: a time course study

“…Arg synthesis depends on the citrulline concentration, it requires aspartate and takes place essentially in the proximal convoluted tubules [13,25]. In kidneys, the highest level of Arg is located in the cortex followed by the outer stripe of the outer medulla -two zones where the proximal tubules lie [27]. In animals submitted to experimental nephrectomy, destroying the proximal tubules results in an enhancement of citrullinemia and an accumulation of citrulline in extra-renal organs in proportion to renal damage [8,28,49].…”

Simultaneous determination of guanidinosuccinic acid and guanidinoacetic acid in urine using high performance liquid chromatography/tandem mass spectrometry

“…In the previous study [22,26], GAA was decreased in 24-h urine samples from uremic patients, since urine production would be impaired in a substantial portion of the kidney. It was reported that GSA and GAA are localized in the inner medulla and cortex of the kidney, respectively [27]. These observations possibly indicate that GSA is the first to increase as a urinary marker in the inner medulla, and that GSA promotes the production of NO via NMDA receptors [28,29].…”

Dehydration modifies guanidino compound concentrations in the different zones of the rat kidney

“…Each of the natural GCs: Arg, GAA, guanidinosuccinic acid (GSA), CT, creatinine (CTN), homoarginine (HArg), α-N-acetylarginine (α-N-AA), β-guanidinopropionic acid (β-GPA), γ-guanidinobutyric acid (γ-GBA), α-keto-δ-guanidinovaleric acid (α-keto-δ-GVA), guanidine (G) and methylguanidine (MG) exhibit typical distribution patterns along the cortico-papillary axis [16]. Moreover, it is noteworthy that, in adult rats, the tissue concentrations of α-keto-δ-GVA, GSA, CTN, MG, α-N-AA and γ-GBA increase steeply from the inner stripe of the outer medulla to the papillary tip and, thus, constitute gradients which run in parallel to the well-known urea and osmotic gradients [26,31].…”

“…GCs have been localized within the mammalian kidney and are unevenly distributed along the cortico-papillary axis of the rat kidney [16]. Each of the natural GCs: Arg, GAA, guanidinosuccinic acid (GSA), CT, creatinine (CTN), homoarginine (HArg), α-N-acetylarginine (α-N-AA), β-guanidinopropionic acid (β-GPA), γ-guanidinobutyric acid (γ-GBA), α-keto-δ-guanidinovaleric acid (α-keto-δ-GVA), guanidine (G) and methylguanidine (MG) exhibit typical distribution patterns along the cortico-papillary axis [16].…”