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W C Kruckeberg

Publications and source records attributed to W C Kruckeberg.

At least 19 recordsLinked to original sources
PubMed1999

Differential expression of renal nitric oxide synthase isoforms during pregnancy in rats.

Alterations in nitric oxide (NO) production have been suggested to play a role in mediating changes in renal function during normal pregnancy and in pregnancy-induced hypertension. Although NO production is enhanced during normal pregnancy, the mechanisms for the increase are unknown. The purpose of this study was to determine whether the elevation in NO production during pregnancy is associated with increases in renal expression of endothelial (eNOS), inducible (iNOS), and neuronal (nNOS) nitric oxide synthases. To achieve this goal we examined systemic and renal hemodynamics, urinary excretion of nitrate/nitrite, and renal protein expression of the three NOS isoforms in prepregnant rats, pregnant rats at days 6, 13, and 19 of gestation and at day 4 postpartum. Mean arterial pressure decreased by 14% in late pregnancy whereas the glomerular filtration rate and renal plasma flow increased by 21% and 24%, respectively, in mid pregnancy. Excretion of nitrate/nitrite increased throughout pregnancy with a 3.4-fold increase present at day 19 (12.2+/-0.7 to 41.1+/-1.3 micromol/24 h). Renal eNOS protein expression decreased by 39% during pregnancy with the lowest level resulting at day 19 and returning to virgin levels by day 4 post partum. In contrast, renal iNOS and nNOS protein expression increased 31% and 25%, respectively, with highest expression occurring for both at day 13 of pregnancy. These data suggest that the increased NO production and renal hemodynamics associated with pregnancy in rats may be caused by the upregulation of iNOS and nNOS in the kidney.

Animals↗
PubMed1994

Changes in nitric oxide precursor, L-arginine, and metabolites, nitrate and nitrite, with aging.

The present study was performed to test the hypothesis that excretion of nitric oxide metabolites, nitrate and nitrite, are decreased with progressive aging in rats and that a decrease in nitric oxide precursor, L-arginine, also decreases with aging. Urinary nitrate/nitrite excretory rates and serum L-arginine levels were measured in male Sprague Dawley rats, ranging in ages from 3 to 25 months. Proteinuria increased dramatically with aging. Conversely, urinary nitrate/nitrite excretion decreased by 50% and 80% in rats, aged 12 months and 17 months, respectively. There was no further decrease in urinary nitrate/nitrite excretion in very old rats, aged 23-24 months. Glomerular filtration rate (GFR) was also measured in some of the rats, aged 3-5 mos and 17 mos. GFR was not different between old and young rats, suggesting that a decrease in GFR could not account for the decrease in urinary nitrate/nitrite excretion in the old rats. However, serum L-arginine levels were decreased with aging, by 30% and 50% in rats, aged 13-15 months and 24-25 months, respectively, when compared with young rats. These data confirm our hypothesis and suggest that nitric oxide (NO) production may decrease with aging and that one mechanism by which nitric oxide production could be decreased with age is a lack of the endogenous substrate, L-arginine. Because NO has been implicated to be involved in many physiological processes, age-related decreases in NO production could have far-reaching adverse effects in the aging individual.

Aging↗
PubMed1991

Factors influencing variable oxidative hemolysis of inbred mouse erythrocytes.

The hemolysis of erythrocytes from certain inbred mouse strains (e.g., BALB/c) in response to hydrogen peroxide stress has been shown to be correlated with the type of hemoglobin beta chain (Kruckeberg, W.C., et al. (1987) Blood 70, 909-914). The characteristic hemolytic response of BALB/c red cells to oxidative stress resembles that of human red cells in that carbon monoxide and iron chelators inhibit hemolysis of both. Gross hemoglobin oxidation rates were similar in hemolytic (BALB/c) and nonhemolytic (C57BL/6) strains. The rate and degree of in vitro catalase inhibition by sodium azide was also the same for the two strains. Even in the presence of this catalase inhibitor the assayable hydrogen peroxide disappeared within seconds of its addition, yet hemolysis was not observed for about 15 min. The mechanism underlying this delay between hydrogen peroxide addition and disappearance and subsequent hemolysis is under investigation.

Animals↗
PubMed1987

Genetic differences in hemoglobin influence on erythrocyte oxidative stress hemolysis.

The RBC from mice of certain inbred strains hemolyzed under oxidative stress (2.0 mmol/L hydrogen peroxide), whereas red cells from mice of other strains did not. In the experimental system human erythrocytes did not hemolyze. The rate of formation of malonyldialdehyde (a fatty acid oxidative breakdown product) was fourfold higher in hemolytic v nonhemolytic red cells. There was insufficient variation in the levels of glutathione, peroxidase activity or its substrate, reduced glutathione, to explain these hemolysis differences. On the other hand, the antioxidants butylated hydroxyanisole and hydroxytoluene, and histidine protected the hemolysis-prone red cells from breaking open. The hemolysis trait demonstrated autosomal recessive Mendelian inheritance. When using inbred, recombinant inbred, and congenic inbred mice, this hemolysis/nonhemolysis trait correlated 1:1 with the type of hemoglobin beta chain in the RBC. This experimental system is a potential model for investigating the role of hemoglobin in prehemolytic events.

Animals↗
PubMed1979

Zinc inhibition of calmodulin: a proposed molecular mechanism of zinc action on cellular functions.

Calcium stimulates, and zinc inhibits, a wide variety of cell types. In the erythrocyte, we have found calcium and zinc to have antagonist actions in a variety of systems. An important mechanism for calcium effects on cells is activation of calmodulin. Calmodulin is a small ubiquitous protein which, when activated by calcium, has a large array of cellular regulatory functions. We now report that calmodulin function is inhibited by low concentrations of zinc. Zinc inhibition of calmodulin provides a rational molecular mechanism for the diverse cellular inhibitory effects of zinc, as well as for zinc's antagonism of calcium effects.

Adenosine Triphosphatases↗
PubMed1979

Regulation of avian erythrocyte AMP-deaminase.

1. Kinetic data for avian erythrocyte AMP-deaminase in lysate supernatants and 2000-fold purified enzyme were consistent with an allosteric model having four binding sites for substrate. 2. Relative to the purified enzyme, AMP-deaminase in lysate supernatants exhibited a greater S0.5 and enhanced sensitivity toward phytic acid, but was far less sensitive toward potassium ion. 3. In the absence of potassium chloride, the enzymatic activity in lysates exhibited hysteresis at subsaturating 5'-AMP. This response was modified reversibly by allosteric ligands. 4. It is concluded that the characteristics of avian RBC AMP-deaminase, as expressed in lysates, may reflect important intermolecular interactions and better represent the regulatory properties of this enzyme in erythrocytes.

AMP Deaminase↗
PubMed1978

Erythrocyte AMP-deaminase: an investigation of the increase in activity during chick maturation.

1. AMP-deaminase activity in erythrocytes increases gradually during chick (Gallus domesticus) maturation, reaching the adult level of enzymatic activity at about 16 weeks after hatching. 2. Adenosine deaminase activity increases approximately two-fold during this period. 3. Substrate specificity and immunoinhibition studies indicate that erythrocytes from adult chickens and newly-hatched chicks contain the same AMP-deaminase isozyme. 4. Comparison of temporal changes in RBC AMP-deaminase with those previously described for this enzyme in muscle and brain suggests that the level of this enzyme is regulated differently in these tissues.

AMP Deaminase↗
PubMed1978

The mechanism and control of human erythrocyte zinc uptake.

The increasing awareness of the importance of the divalent cation zinc in normal and pathologic cell functions has prompted our investigations into the mechanism and control of human erythrocyte zinc uptake. The albumin in blood plasma appears to be the main zinc binding moiety, effectively limiting zinc availability ot the red cell. In non-protein and non-phosphate-containing buffers (i.e., bicarbonate or Tris buffer) red cells sequester more than 90% of the extracellular zinc within 10--15 minutes at a rate more than 250 times faster than zink uptake by cells in plasma. In an albumin-containing media, the influx on red blood cell zinc is lightly temperature sensitive (decreased) between 37 degrees C and 25 degrees C, whereas with cells in bicarbonate buffer alone temperature sensitivity does not begin until below 25 degrees C. Over the physiological range, pH variation has a minimal effect on zinc uptake regardless of the media employed. Finally, once associated with the red cell zinc tends to remain, with a zinc efflux less than 2% of influx. We conclude that human erythrocytes are highly permeable to zinc, with the rate and amount of zinc taken up controlled primarily by the zinc binding characteristics of the media in which the cells are suspended.

Anemia, Sickle Cell↗