Uncoupling of oxidative phosphorylation by ultrafiltrates of uremic serum

Effects of parathyroid hormone infusion on glucose tolerance and glucose-stimulated insulin secretion in normal and uremic rats

We used thyroparathyroidectomized (TPTX) rats with hypocalcemia to evaluate the effects of parathyroid hormone (PTH) infusion on glucose tolerance and glucose-stimulated insulin secretion in normal and uremic rats. Animals were subjected to oral glucose tolerance test (OGTT) and glucose-stimulated insulin secretion before and after TPTX or after their plasma calcium level was normalized by PTH infusion, vitamin D injection or calcium load. In both normal and uremic groups, TPTX produced a significant increase in area under the cure (AUC) of plasma glucose from 0 to 6 h in response to an oral glucose challenge and decrease plasma insulin level in response to glucose-stimulated insulin secretion. Before TPTX, uremic animals have a normal basal plasma insulin level (29 +/- 3 versus 31 +/- 2 microU/ml) and a normal glucose-stimulated insulin secretion, but significantly increase plasma glucose AUC in response to OGTT as compared with normal rats. TPTX worsen the response of glucose intolerance in uremic rats. After PTH infusion, vitamin D injection or calcium load, all rats in the response of OGTT and glucose-stimulated insulin secretion are recovered to the level before TPTX including normal and uremic rats, but uremic rats still have an abnormal glucose tolerance in response to OGTT. Uremic rats have a low basal plasma glucose level as compared with normal rats. TPTX significantly increase basal plasma glucose level in normal and uremic rats, but the uremic rats with TPTX have been found to elevate basal plasma glucose level to the range of normal rats. The basal plasma glucose level of normal rats with TPTX was recovered to the range before TPTX by PTH infusion, vitamin D injection or calcium load, but PTH infusion, vitamin D injection or calcium load did not decrease the level of basal plasma glucose in uremic rats with TPTX. All TPTX rats, including intact kidney or five-sixths Nx rats, were treated three times weekly by subcutaneous injection of 8 micrograms/kg L-thyroxin. These results indicate that uremia may produce thyroid dysfunction and PTH infusion did not affect the glucose tolerance in OGTT and glucose-stimulated insulin secretion in normal and uremic rats. In addition to PTH, other uremic toxins may be responsible for the glucose intolerance of uremia.

Carbohydrate metabolism in uremia

Abnormalities of insulin and glucose metabolism, namely glucose intolerance, inhibition of insulin secretion and insulin resistance, are present in children with chronic renal failure. Insulin resistance is universal among children with end-stage renal disease and may be caused by uremic toxins accumulated because of reduced renal function. The normal response of the beta cell is to enhance insulin secretion to overcome the insulin resistance. In patients with secondary hyperparathyroidism, this increase in insulin secretion is inhibited, resulting in glucose intolerance. Presence of glucose intolerance may be responsive for the growth retardation in uremic children. Improvements in glucose tolerance correlate with improvements in linear growth in uremic children. Further research should be directed towards investigation of the mechanisms by which abnormal energy utilization may affect growth in uremia and development of indices of glucose metabolism as predictors of growth in uremia.

Morphological changes of the liver in uremic patients treated with chronic hemodialysis--laparoscopic observations and light- and electron-microscopic studies

In order to clarify morphological changes of the liver in the uremic state, 16 uremic patients treated with chronic hemodialysis were studied. Biopsy was performed in 14 cases under laparoscopic observation and in two on the occasion of renal transplantation. One uremic patients not being treated with dialysis was also studied for comparison. All biopsy specimens were examined by light and electron microscopy. The liver usually appeared mildly or moderately swollen under laparoscopic observations, which was considered at least partially due to the enlargement of the hepatocytes. All patients had hepatocytes with an Orcein-negative "ground glass" appearance, in which marked proliferation of smooth endoplasmic reticulum (SER) was found by electron microscopy. Since the patient not being on dialysis also had such hepatocytes, this finding may be characteristic of uremia. With electron microscopy, in addition to proliferation of SER, alteration of mitochondria and rough endoplasmic reticulum (RER) and an increase in cytoplasmic lipid droplets were observed. Hypertrophy of the Golgi apparatus containing electron-dense particles (VLDL) was often found in patients associated with hypertriglyceridemia. Amorphous electron-dense inclusions in microbodies were occasionally observed. Siderosis was observed in nine patients including three having parenchymal siderosis. With electron microscopy, various siderosomes were seen in the cytoplasm of hepatocytes in patients with parencymal siderosis. Conclusively, these histological and ultrastructral features of hepatocytes are rather associated with several metabolic abnormalities in uremia.