title: Changes in glomerulotubular dimensions, single nephron glomerular filtration rates and the renin-angiotensin system in hypothyroid rats.
abstract: Glomerular diameters (GD) and lengths of attached proximal convoluted tubules (TPL) were measured in nephrons dissected from the superficial (S), intermediate and juxtamedullary (JM) cortex (7-15 each) of acid-macerated kidneys of weight-matched (E) euthyroid and (H) hypothyroid (2-6 months after radioiodine treatment or thyroidectomy) male Sherman-Wistar rats. Incoordination of growth in H rats was evident in a more marked retardation in kidney than in total body growth. A similar incoordination of microstructural growth was evident in maintenance or GD within normal limits with respect to body weight while attached TPL fell 23% on the average below control values relative to body weight. These changes affected the total nephron population uniformly. As a result, GD/TPL in all nephrons increased significantly (p less than 0.01), by 27% in S and by 29% in JM nephrons. The glomerulotubular dimensional imbalance was associated with a marked and uniformly distributed reduction in single nephron glomerular filtration rate (ferrocyanide method), by 36% in S and JM nephrons. Plasma renin activity fell within normal limits while plasma renin substrate was decreased to 56% of control values. These findings are construed as evidence that growth retardation in hypothyroid rats affects the parenchyma of the kidney (and perhaps other viscera) more than the vasculature.
mesh_terms: D000804:Angiotensin II / Q000097:blood*; D000818:Animals; D005919:Glomerular Filtration Rate; D007037:Hypothyroidism / Q000503:physiopathology*; D007678:Kidney Glomerulus / Q000503:physiopathology*; D007687:Kidney Tubules, Proximal / Q000503:physiopathology*; D008297:Male; D009399:Nephrons / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D012083:Renin / Q000097:blood*
chemical_list: D000804:Angiotensin II; D012083:Renin