RESUMEN
Standard micropuncture and microdissection techniques were used to examine the function and structure of nephrons in rats whose kidneys were made cystic by dietary exposure to diphenylamine. Heterogeneity characterized the lesion, with dilation and frank cyst formation occurring in 5-30% of nephrons. Elevated intraluminal hydrostatic pressures, occurring in the absence of increased glomerular filtration or decreased net water reabsorption, were recorded in dilated, but not in nondilated nephrons. Structural studies demonstrated communication of dilated nephrons with cysts, concretions of debris within tubular lumens, evidence of extrinsic pressure by cysts on adjacent tubules, and apparent luminal narrowing of some proximal tubules. These observations were used to explain prolonged loop of Henle transit times and occasional failure to detect [3H]inulin excretion after microperfusion into dilated tubules. It was concluded that the elevated hydrostatic pressures in the dilated nephrons of diphenylamine-exposed kidneys were the consequence of variably severe and frequently incomplete tubular occlusion. These findings support the hypothesis that cyst formation is a consequence of partial obstruction and elevated intratubular pressure in this model and perhaps in other susceptible mammalian kidneys.
Asunto(s)
Compuestos de Anilina , Difenilamina , Modelos Animales de Enfermedad , Enfermedades Renales Quísticas/inducido químicamente , Animales , Líquidos Corporales/metabolismo , Peso Corporal/efectos de los fármacos , Tasa de Filtración Glomerular , Presión Hidrostática , Inulina , Corteza Renal/patología , Enfermedades Renales Quísticas/patología , Enfermedades Renales Quísticas/fisiopatología , Túbulos Renales/efectos de los fármacos , Túbulos Renales/patología , Asa de la Nefrona/efectos de los fármacos , Masculino , Nefronas/efectos de los fármacos , Nefronas/fisiopatología , Aceites/farmacología , RatasRESUMEN
We studied the role of the urinary bladder of Bufo marinus in the excretion of bicarbonate into the urine. The toads were in metabolic alkalosis, produced by administering 120 mM NaHCO3 by stomach tube or by soaking the toads in 120 mM NaHCO3 solution for 48 to 72 hr. In vitro 10 cannulated whole bladders from toads in alkalosis transported bicarbonate from the serosal to mucosal medium. The average gradient created by this transport was 5.7 meq/1. In 15 whole bladders from toads in metabolic acidosis studied under identical conditions, there was no transport of bicarbonate into mucosal medium.