Effect of estrogen-progestogen administration on tissue cation concentrations in the rat.

Five studies are reported which were designed to define the effects of an estrogen and a progestogen, alone and in combination, on tissue concentrations (heart, kidney, and liver) of two trace metals (zinc, copper) and four bulk cations (sodium, potassium, calcium, magnesium). Male rats received Premarin (0.08 mg) and/or progesterone (2 mg) in saline intramuscularly 5 days a week for 12 weeks. A significant increase in kidney copper concentrations was the most striking finding in treated, compared to control, animals. A small but significant increase in kidney zinc concentrations also was observed. The changes in cation concentrations in the liver were less striking and consistent, and no changes were observed in cation concentrations of heart muscle. The increase in renal copper was greater with estrogen than with progestogen alone but the two in combination produced an additive effect. Dose-response and time-response changes were documented. Two weeks after discontinuing treatment, renal copper and zinc concentrations returned to control levels.

Influence of synthetic corticosteroids on plasma zinc and copper levels in humans.

The effects of varying doses of a short-acting (methylprednisolone) and a long-acting (dexamethasone) synthetic glucocorticoid on extent and duration of alterations in plasma zinc and copper concentrations in normal humans are documented. Early after intravenous administration of either steroid, increases in plasma zinc and copper levels were observed. By 12 hours, plasma zinc concentrations had decreased below control levels and the extent and duration of the depression depended on the dosage of the steroid administered. No significant decrease was noted beyond 48 hours. The plasma copper levels did not decrease until after zinc levels began returning toward normal, reaching a peak depression at 48 hours and, at high doses of steroids, persisting until completion of the study at 96 hours. This difference in the time sequence suggests that different mechanism control plasma concentrations of the two metals. The serum zinc levels may depend on ACTH-adrenal interactions, while the slower response of the serum copper levels may depend on changes in the rate of synthesis of the serum copper-binding protein, ceruloplasmin.

Serum concentrations and urinary excretions of zinc in cirrhosis, nephrotic syndrome and renal insufficiency.

Serum zinc conentrations are decreased in patients with a variety of clinical disorders including cirrhosis, nephrotic syndrome and renal insufficiency. Urinary zinc excretions are increased in the first two disease states. Symptoms of acute zinc deficiency (anorexia, dysfunction of smell and taste and mental and cerebellar disturbances) and chronic zinc deficiency (growth retardation, anemia, testicular atrophy and impaired wound healing) are common in these patients. It remains unresolved whether these low serum zinc concentrations in these disease states are indicative of true symptomatic or asymptomatic zinc deficiency, or merely reflect a decrease in available zinc-binding proteins, as well over 90% of serum zinc is bound to protein in normal subjects. The correlation between serum zinc and albumin concentrations, reportedly the major zinc-binding protein, is unimpressive. Studies of serum and urine binding of added radiozinc65 using Sephadex G-200 gel column chromatography and polyacrylamide gel electrophoresis suggest most of the radiozinc is bound to a protein with a molecular weight near albumin (68,000). Polyacrylamide gel electrophoresis suggests this might be a prealbumin. The low serum zinc concentration in the patient with nephrotic syndrome does not appear to be due to loss of zinc bound to urinary protein.

Rapid development of glomerular crescents in epinephrine-infused dogs.

A serendipitous finding in the kidneys examined by light, electron, and immunofluorescence microscopy (LM, EM, and IFM, respectively) in mongrel dogs infused intravenously with epinephrine (4 microgram per kg per min) alone or in combination with therapeutic agents over a six hour period was proliferating epithelial cells in Bowman's space and adhesion to the Bowman's membrane (crescent). This lesion was observed in 10 of 17 dogs. In five, over 50 percent of the glomeruli were involved. In seven additional dogs infused with epinephrine, renal biopsy studies (LM) at 0, 3 and 6 hr periods revealed crescents only in the six hr specimens. By EM, the crescents were composed of actively proliferating epithelial cells with many large mitochondria containing conspicuous intramitochondrial particles. Fibrin was found within glomerular and peritubular capillaries, within tubules but rarely in the crescent. IFM revealed granular deposits of IgG only in the glomerular basement membrane and mesangium. Other changes included necrosis of the tubules in all dogs receiving epinephrine alone and necrosis of arterioles in some of the dogs studied. Dogs receiving normal saline infusions (control) did not reveal any abnormalities in the kidney. This model should prove useful in determining the morphogenesis of crescent formation and in evaluating the effect of therapeutic agents in the prevention of this lesion.

Comparison of renal and cardiac lymph constitutents.

The concentration of various substances were measured in renal and cardiac lymph and arterial and venous plasma to determine if lymph constituents might indicate events occurring at the cellular level in these two organs. The study utilized anesthetized dogs. Magnesium, calcium, pyruvate and glucose concentrations were similar in the four fluids. Cardiac lymph contained significantly higher concentrations of creatine phosphokinase, lactic dehydrogenase and lactate. Renal lymph contained lower concentrations of zinc and protein while both renal and cardiac lymph contained less copper than arterial plasma. Venous plasma contained more copper than the other fluids. It is concluded that lymph composition reflects events occurring in the cells, especially for substances that are not readily diffusable through blood capillary endothelium.

Renal excretion of chromium-51 chloride in the dog.

To examine the renal handling of the trace element chromium, clearance studies were performed in pentobarbital sodium-anesthetized mongrel dogs following either gavage or intravenous administration of chromium-51(III) chloride. Ultrafilterable plasma chromium-51 comprised as much as 9-19% of the total plasma chromium-51 when the isotope was given by gavage but only 2-3% when given by intravenous infusion. The mean ratio of the clearance of ultrafilterable plasma chromium-51 to that of endogenous creatinine was approximately unity in all dogs [0.97 +/- 0.11 to 1.14 +/- 0.10 by gavage (n = 5); 0.84 +/- 0.05 to 0.97 +/- 0.05 intravenously (n = 4)]. Regardless of the route of administration, ultrafilterable plasma chromium-51 concentration and glomerular filtration rate appeared to be the primary determinants of renal chromium-51 excretion.

Zinc metabolism in renal disease and renal control of zinc excretion.

Serum zinc concentrations are decreased in patients with a variety of clinical disorders including cirrhosis, nephrotic syndrome and renal insufficiency. Urinary zinc excretions are increased in the first two disease states. Symptoms of acute zinc deficiency (anorexia, dysfunction of smell and taste, and mental and cerebellar disturbances) and chronic zinc deficiency (growth retardation, anemia, testicular atrophy, and impaired wound healing) are common in these patients. It remains unresolved whether these disease states are indicative of true symptomatic or asymptomatic zinc deficiency or merely reflect a decrease in available zinc binding proteins. The low serum zinc concentrations and high urinary zinc excretions in patients with nephrotic syndrome do not appear to be due to loss of zinc bound to urinary proteins. Studies in dogs indicate increased serum and urine concentrations of certain amino acids(cysteine, histidine) greatly increase urinary zinc excretions. Studies are now underway to determine if the hyperzincuria and hypozincemia of cirrhosis, nephrotic syndrome and hyperalimentation can be explained by an increase in these urinary amino acids.

Effects of acetylsalicylic acid, dipyridamole, and hydrocortisone on epinephrine-induced myocardial injury in dogs.

A reproducible model for producing diffuse myocardial injury (epinephrine infusion) has been developed to study the cardioprotective effects of agents or maneuvers which might alter the evolution of acute myocardial infarction. Infusions of epinephrine (4 mug per kilogram per minute for 6 hours) increased radiocalcium uptakes into intact myocardium and each of its subcellular components with the mitochondrial fraction showing the most consistent changes when compared to saline-infused control animals (4,957 vs. 827 counts per minute per gram of dried tissue or fraction). Myocardial concentrations of calcium also increased significantly (12.0 vs. 5.0 mg.per 100 Gm. of fat-free dry weight). Infusions of calcium chloride sufficient to raise serum calcium concentrations 2 mEq. per liter failed to increase calcium influx into the myocardial cell. Mitochondrial radiocalcium uptakes were significantly decreased in animals pretreated with acetylsalicylic acid or dipyridamole or when hydrocortisone was added to the epinephrine infusion (2,682,2,803, and 3,424 counts per minute per gram of dried fraction, respectively). Myocardial calcium concentrations also were decreased (11.2, 8.3, and 8.9 mg. per 100 Gm. of fat-free dry weight, respectively) in the three treatment groups, being significantly decreased only in the last two. Evidence of microscopic damage was graded as less severe in the three treatment groups. Acetylsalicylic acid, dipyridamole, and hydrocortisone all appear to have cardioprotective effects when tested in this model.

Impairment of ascorbic acid synthesis in liver extracts of magnesium-deficient rats.

The effect of feeding a magnesium (Mg)-deficient diet for 9-34 days to weanling and young male rats on urinary and tissue ascorbate levels were studied. The concentrations of ascorbic acid in the liver and kidney were significantly reduced in the rats receiving a Mg-deficient diet as compared to those receiving a Mg-supplemented diet. The response to trichloro-2-methyl-2-propanol stimulation of urinary ascorbic acid was found to be considerably suppressed by dietary deficiency of Mg, suggesting that the decrease was not due to feed intake. In in vitro studies, the enzymatic synthesis of the vitamin from glucuronolactone or gulonolactone by liver extracts from Mg-deficient rats was significantly decreased as compared with Mg-supplemented rats. These results suggest that Mg-deficient rats have a reduced capacity to synthesize ascorbate which in turn produces a decrease in ascorbic acid concentrations in the liver.

Ethanol-ascorbate interrelationship in acute and chronic alcoholism in the guinea pig.

The effects of low (200 ppm) and of high (2000 ppm) ascorbic acid, in a nutritionally adequate diet, on blood ethanol levels have been studied in permanently carotid-cannulated, ethanol-infused, unanesthetized guinea pigs. In the acute study, the postinfusion rate of ethanol decline in the blood of animals treated with ascorbic acid was significantly higher when compared with animals treated with fructose, and the rate in the two treated groups was significantly higher than in untreated controls. In the chronic study, animals were infused with sublethal doses of ethanol (30% of the total caloric intake) for 8 weeks. Blood ethanol levels monitored throughout this period showed, at 3 hr postinfusion, a lower concentration in the group on a high ascorbic acid diet. Both experimental groups receiving ethanol lost significantly more body weight in the second week of dieting; but, while the group on high ascorbic acid regained weight steadily thereafter, the group on low ascorbic acid was still 50 g below the controls at the end of the experiment. Liver, kidney, and adrenal ascorbic acid concentrations were lower in the ethanol-treated groups compared to controls. Examination of the liver revealed more fatty metamorphosis or steatosis in the low ascorbic acid group, but there was no evidence of liver fibrosis or cirrhosis. These results demonstrate the feasibility of utilizing the guinea pig for the study of the biochemical and morphological sequelae of alcoholism. They further support the contention that a diet which is nutritionally adequate may no longer be so in the presence of high ethanol intake, and that supplemental vitamin C ingestion may afford protection against ethanol toxicity.

Urinary zinc excretion following infusions of zinc sulfate, cysteine, histidine, or glycine.

Zinc sulfate (40 mg elemental zinc) or one of three amino acids (5 or 10 g cysteine, 10 g histidine, or 10 g glycine) was infused into anesthetized dogs over a 60-min period. Plasma concentrations and urine excretions of zinc and five other cations, and glomerular filtration rates were determined before, during, and after these infusions. Infusions of zinc sufficient to produce a 20-fold increase in total plasma zinc concentrations had little effect on urinary zinc excretions (threefold increase) or plasma ultrafilterable zinc concentrations. Ten grams of cysteine urinary zinc excretions more than 100-fold, 5 g of cysteine increased zinc excretions more than 30-fold, 10 g of histidine increased zinc excretions sixfold, and 10 g of glycine had no effect. Cysteine infusions appeared to produce a net tubular secretion of zinc. Only histidine appeared to increase serum ultrafilterable zinc concentrations significantly. It would appear that plasma and urine concentrations of certain amino acids, specifically cysteine and histidine, along with polypeptides and other metabolites containing these amino acids, may be major determinants of urinary zinc excretion.

The effect of magnesium depletion on thyroid function in rats.

The effects of dietary magnesium (Mg) depletion on thyroid function were studied in young male rats. The rats were fed a semipurified diet containing either 12 ppm Mg (deficient rats) or 662 ppm Mg (control rats) for 14 to 28 days. Results showed that the Mg-deficient rats had decreased body weight gain, lowered concentrations of plasma thyroxine (T4) and Mg, but increased weight of the thyroid gland when expressed in proportion to the body weight (milligrams/100 g). There was no difference in the accumulation (uptake) of 131I, 24 hours after Na131I injection, between the Mg-deficient and Mg-supplemented rats. The protein-bound 131I (PB131I) level and the ratio of PB131I to total 131I in plasma was significantly reduced in Mg-deficient rats. Serum thyroid-stimulating hormone (TSH) levels after thyrotropin-releasing hormone injection (TRH, 50 ng/100 g body weight) increased fivefold at 30 minutes, but declined to near the basal level at 2 hours in both groups. No consistent difference in TSH response was observed between the two treatments. Serum T4 response to TRH challenge was significantly reduced in Mg-deficient as compared to Mg-adequate rats at all time intervals. The reduction of T4 level could be due to an impaired T4 synthesis or release in Mg-deficient rats.

Effects of acute and chronic splenectomy on experimental acute renal tubular lesions.

The first half of this study describes the effects of acute splenectomy on epinephrine-induced ATL in the dog. Renal morphology and hematocrit were compared in 12 dogs without splenectomy (group I), six dogs with antecedent splenectomy (group II), and seven dogs with antecedent splenectomy after splenic contraction was induced by topical application of epinephrine (group III). Splenectomy was performed in groups II and III 20 to 30 min prior to epinephrine infusion; all three groups received equal infusions (4 microgram/kg/min) for 6 hr before the kidneys were harvested. ATL and renal congestion were consistently severe in group I but infrequent and less severe in groups II and III. The second half of this study describes the apparent protective effect of chronic (2-week) splenectomy on epinephrine-induced ATL. Renal morphology and hematocrits were compared in 13 intact dogs (group IV) and 10 dogs splenectomized 2 weeks before the epinephrine infusion (group V). The severity of the ATL and the degree of renal congestion were significantly less in the chronically splenectomized dogs. This chronic protection afforded by acute and chronic splenectomy observed after epinephrine infusion remains unclear.