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Biomedical subjects

H G Preuss

Publications and source records attributed to H G Preuss.

At least 127 records · Page 7Linked to original sources
PubMed1977

Effect of renal fuels on p-aminohippurate transport in rat renal cortical fragments.

The effects of the major renal fuels were studied, i.e., lactate, citrate, palmitate, glutamine, and glucose, at concentrations near those found circulating on the in vitro accumulation of p-aminohippurate (PAH) by rat renal cortical fragments. Only lactate and citrate were found to increase PAH uptake significantly. Noting that 10% v/v normal rat sera enhance PAH accumulation, we studied the renal fuels at 10% circulating concentrations and found that all fuels combined had stimulation comparable to 10% v/v sera. Lactate and the stimulator in normal sera are located in the same Sephadex G-25 fraction of sera. Both lactate, the major renal fuel, and normal sera stimulate the influx and inhibit the efflux of PAH. We conclude that the stimulators to PAH transport in normal sera are, at least in part, renal fuel organic anions.

Aminohippuric Acids↗
PubMed1976

The effects of high calcium concentrations on renal ammoniagenesis by rat kidney slices.

Deficiencies in acid excretion during hypercalcemia have been reported, and this defect has been ascribed to a deficiency in ammonia excretion. Because no changes in urine pH and urine flow occurred to explain decreased ammonia excretion, this suggested to us that decreased excretion was secondary to decreased renal ammonia production. To test this hypothesis, we investigated the ability of kidney slices from rats to produce ammonia and glucose and to consume oxygen when incubated in varying concentrations of calcium. High medium concentrations of calcium (3 and 4 mM) decreased kidney slice ammonia-genesis from glutamine and glutamine and kidney slice oxygen consumption while not affecting gluconeogenesis. Based upon our findings, we propose that hypercalcemia decreases urine ammonia excretion by depressing renal ammonia production.

Ammonia↗
PubMed1976

A renotropic system in rats.

While plasma or sera obtained from rats 20 h after removal of one kidney (uninephrectomy) stimulated [3H] thyrmidine incorporation into the DNA of kidney tissue incubating in vitro, azotemic plasma or sera obtained from rats 20 h after removal of both kidneys had no apparent effect. Dialysis of this azotemic sera resulted in its ability to stimulate isotope incorporation into renal DNA to the same degree as sera from uninephrectomized rats. This stimulatory factor (renotropin) was found to rise significantly within the first 26 h after uninephrectomy. Renotropin worked only on renal tissue, and we found that a factor could be extracted in large amounts from the remaining kidney 20 h after uninephrectomy that would stimulate renal DNA synthesis in the presence of sera. Based on these findings and others, we postulate that after uninephrectomy there is an elevation in circulating renotropin as well as a tissue factor in the remaining kidney. Both factors together probably produce an excitor which enhances [3H] thymidine into DNA. The latter is tightly bound to renal tissue, and its production and/or activity is modified by circulating inhibitors that are especially prominent in azotemia.

Animals↗
PubMed1976

Effect of para-aminohippurate on renal glutamine metabolism in the rat.

After para-aminohippurate (PAH) infusion into rats, urine pH decreased and urine ammonium excretion increased. Because augmented urine flow and decreased urine pH could not explain entirely the enhanced ammonium excretion, an increased ammonia production was postulated as a contributing influence. This was supported by the in vitro findings that PAH could increase slice ammoniagenesis from glutamine. The ability of PAH to stimulate ammoniagenesis in vitro was attributed to enhanced phosphate-dependent glutaminase activity. We conclude that PAH infusions at certain concentrations in vivo can alter ammonium excretion through increased renal ammonia production. The latter may be secondary to enhanced phosphate-dependent glutaminase activity.

Aerobiosis↗
PubMed1975

Hypomagnesemia following the diuresis of post-renal obstruction and renal transplant.

Three unusual cases are described which demonstrated hypomagnesemia and symptoms resembling magnesium deficiency syndrome. The hypomagnesemia was most likely secondary to urinary losses from diuresis following release of post-renal obstruction and renal homotransplantation. Heretofore, this association has not been described. Case 1 was unique because of the post-obstructive diuresis in the face of marked renal impairment. Case 2 is noteworthy because of the profound hypomagnesemia, 0.4 mEq/1, and because of the development of congestive heart failure. The rapid improvement noted in cardiac function with magnesium replacement suggests a relationship to magnesium deficiency.

Adult↗
PubMed1975

Measurement of renal blood flow in the rat.

The radioactive microsphere technique is a simple method for measurement of RBF and intrarenal blood flow distribution in the rat that does not require surgical manipulation of the kidney or general anesthesia. The results are reproducible and compatible with other established techniques.

Animals↗
PubMed1975

Early events in various forms of experimental acute tubular necrosis in rats.

Metabolic and morphologic changes occurred in the kidneys of rats within 3 hours after inciting acute tubular necrosis by completely clamping the renal blood supply, by intramuscular injections of glycerol, and by subcutaneous injections of HgC12. Although the initial trend was for p-aminohippurate and tetraethylammonium transport to decrease and for oxygen consumption, ammonia production, and gluconeogenesis to increase after glycerol, all of these parameters changed in opposite directions after renal pedicle clamping and after subcutaneous HgC12 (4.7 mg. per kg;). In addition, early morphologic changes in glycerol-injected rats differed from those seen with pedicle clamping and low dose HgC12. With high dose HgC12 (25 mg. per kg.), the metabolic and morphologic changes were somewhere in between those seen with the other insults. Coinciding with early metabolic and morphologic changes, cardiac output and renal blood flow decreased soon after the glycerol was given. On the basis of our findings, we cannot ascribe all of the early metabolic and morphologic changes in the glycerol model to ischemia, and we postulate that the circulating heme proteins may be nephrotoxic to ischemic renal tissue.

Acute Kidney Injury↗