hydroxylysine and Body-Weight

The collagen glucosyltransferase of renal cortex is increased in experimental diabetes and this increased may be partially reversed or prevented by insulin treatment. The absence of any consistent increase in the plasma collagen glucosyltransferase level in diabetes argues against the enzyme's having a significant role in the pathological thickening of capillary basement membranes. The biological significance of the increased renal glucosyltransferase activity in chemically-induced diabetes must therefore remain in doubt but it is possible that the high glucose concentration in the blood simply stimulates the synthesis of new enzyme protein in the kidney.

Topics: Animals; Basement Membrane; Blood Glucose; Body Weight; Collagen; Diabetes Mellitus, Experimental; Galactosyltransferases; Glucosyltransferases; Hydroxylysine; Insulin; Kidney Cortex; Male; Rats; Rats, Inbred Strains; Time Factors

Diabetic rats were treated intraperitoneally for 2 week with(+)-catechin in two different dosages or calcium dobesilate and the influence of these substances on protein and basement membrane collagen synthesis was investigated. Both drugs did not alter the diabetic metabolic situation. At the lower dose, (+)-catechin led to a slight decreased and at the higher dose to a small increase of basement membrane collagen synthesis. But compared to untreated controls these differences were statistically not significant. Calcium dobesilate inhibited markedly the raised basement membrane collagen synthesis. However, this effect does not appear to be specific, since the raised general protein synthesis was also reduced. These findings show that the disturbed basement membrane metabolism in diabetes can be influenced without altering the metabolic situation.

Topics: Animals; Basement Membrane; Blood Glucose; Body Weight; Calcium Dobesilate; Catechin; Collagen; Creatinine; Diabetes Mellitus, Experimental; Hydroxylysine; Kidney Glomerulus; Lysine; Male; Rats; Rats, Inbred Strains

A technique is described for the rapid isolation of highly purified preparations of viable glomeruli from rat kidney cortex. The synthesis of protein as judged by the incorporation of [14C]proline into non-diffusible material was shown to be linear for up to 6 h. The synthesis of collagen, measured as non-diffusible 4-hydroxy[14C]proline, was also linear over this period but represented only a small proportion of total protein synthesis. Similar studies conducted in vivo confirmed that collagen synthesis accounted for less than 5% of total protein synthesis in glomeruli. When isolated glomeruli were incubated with [14C]proline, it was found that approximately 16% of the hydroxyproline present in the collagenous component occurred as the 3-isomer. When glomeruli were incubated with [14C]lysine over 90% of the hydroxy[14C]lysine synthesised was glycosylated and most of the glycosylated hydroxy[14C]lysine was present as glucosyl-galactosyl-hydroxy[14C]lysine. The size of the basement membrane collagen synthesised by the isolated glomeruli was estimated by treating the 14C-labelled protein with mercaptoethanol and sodium dodecyl sulphate and then chromatographing the 14C-labelled protein on an agarose column equilibrated and eluted with buffer containing 0.1% (w/v) sodium dodecyl sulphate. The initial form of [14C]collagen synthesised was found to consist of polypeptide chains which had molecular weights of approximately 140 000 and which were shown to be distinctly larger than the polypeptide chains from embryonic chick tendon procollagen. Also when glomeruli were labelled with [14C]proline for 2 h and chased with unlabelled proline for 4 h there was a time-dependent conversion of the initially synthesised collagen moiety to collagen polypeptide chains which co-chromatograph with tendon pro-alpha chains (molecular weight approx. 120 000).

Topics: Animals; Basement Membrane; Body Weight; Centrifugation, Density Gradient; Chromatography, Gel; Collagen; Hydroxylysine; Hydroxyproline; In Vitro Techniques; Kidney Cortex; Kidney Glomerulus; Kinetics; Lens, Crystalline; Male; Proline; Rats; Time Factors

Topics: Aldehydes; Amino Alcohols; Aminocaproates; Animals; Body Weight; Bone and Bones; Bone Development; Borohydrides; Chickens; Chromatography; Collagen; Dipeptides; Hydroxylysine; Male; Oxidation-Reduction; Protein Conformation; Tibia; Tritium; Vitamin D Deficiency