Glomerulotubular balance, dietary protein, and the renal response to glycine in diabetic rats
| Autor: | Aihua Deng, Francis B. Gabbai, Scott C. Thomson, Larry A. Slomowitz, John S. Hammes |
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| Rok vydání: | 2002 |
| Předmět: |
Male
medicine.medical_specialty Physiology Urinary system Kidney Glomerulus Glycine Renal function urologic and male genital diseases Diabetes Mellitus Experimental Physiology (medical) Diabetes mellitus Internal medicine medicine Animals Diabetic Nephropathies Rats Wistar Tubuloglomerular feedback Kidney urogenital system Reabsorption Chemistry medicine.disease Rats Renal glucose reabsorption Kidney Tubules medicine.anatomical_structure Endocrinology Renal physiology Loop of Henle Dietary Proteins Glomerular Filtration Rate |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 282:R1096-R1103 |
| ISSN: | 1522-1490 0363-6119 |
| Popis: | The glomerular filtration rate (GFR) normally increases during glycine infusion, which is a test of “renal reserve.” Renal reserve is absent in diabetes mellitus. GFR increases after protein feeding because of increased tubular reabsorption, which reduces the signal for tubuloglomerular feedback (TGF). Dietary protein restriction normalizes some aspects of glomerular function in diabetes. Renal micropuncture was performed in rats 4–5 wk after diabetes was induced by streptozotocin to determine whether renal reserve is lost as a result of altered tubular function and activation of TGF, whether 10 days of dietary protein restriction could restore renal reserve, and whether this results from effects of glycine on the tubule. TGF activation was determined by locating single-nephron GFR (SNGFR) in the early distal tubule along the TGF curve. The TGF signal was determined from the ionic content of the early distal tubule. In nondiabetic rats, SNGFR in the early distal tubule increased during glycine infusion because of primary vasodilation augmented by increased tubular reabsorption, which stabilized the TGF signal. In diabetic rats, glycine reduced reabsorption, thereby activating TGF, which was largely responsible for the lack of renal reserve. In protein-restricted diabetic rats, the tubular response to glycine remained abnormal, but renal reserve was restored by a vascular mechanism. Glycine affects GFR directly and via the tubule. In diabetes, reduced tubular reabsorption dominates. In low-protein diabetes, the vascular effect is enhanced and overrides the effect of reduced tubular reabsorption. |
| Databáze: | OpenAIRE |
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