Prenatal lead exposure and the pregnancy outcome. A case-control study in southern Poland.

In an attempt to test null hypothesis (Ho): that prenatal lead exposure does not increase the risk of prematurity and the delivery of SGA infants, a case-control study was performed in four hospitals of Southern Poland (Kraków, Rabka, Limanowa, Zakopane). Lead content was determined in maternal and cord blood as well as in head and pubic hair by the GF AAS (Perkin Elmer). A significant interregional variation of lead content in maternal blood was observed.

Regulation of rat kidney mitochondrial metabolism in acute acidosis.

Proximal tubular ammoniagenesis is amplified under conditions of acute and chronic metabolic acidosis. Current hypotheses postulate that alterations in intracellular pH (pHi) or in the pH gradient across the inner mitochondrial membrane (delta pHm) influence mitochondrial glutamine metabolism. Enhanced glutamine transport across the inner mitochondrial membrane might constitute a key regulatory factor in acidosis.

Effect of oxalate on function of kidney mitochondria.

The effects of oxalate on kidney mitochondria were evaluated in vitro to test whether oxalate exposure leads to derangement(s) in mitochondrial function that could in turn promote the formation of kidney stones. Our previous studies demonstrated that oxalate is transported across the mitochondrial membrane via the dicarboxylate carrier. The present studies indicated that oxalate competitively inhibits the uptake and oxidation of exogenous malate and succinate in isolated mitochondria but has no effect on mitochondrial respiration in the presence of a mixture of glutamate plus malate or glutamate plus pyruvate.

Impairment by cyclosporine of membrane-mediated functions in kidney mitochondria.

This study was performed to evaluate whether cyclosporine penetrates kidney mitochondria and impairs mitochondrial functions, causing nephrotoxicity. Exposure of rat kidney cortical mitochondria in vitro to cyclosporine had little effect on the oxidation of glutamate plus malate. Oxidation of succinate was markedly inhibited by a toxic level of cyclosporine (25 to 50 nmol/mg protein) under resting (State 4) and ADP-stimulated (State 3) conditions.

Sites of action of glucagon and other Ca2+ mobilizing hormones on the malate aspartate cycle.

Data from a number of laboratories suggest that the exchange of glutamate for aspartate across the mitochondrial inner membrane is stimulated by glucagon and by Ca2+-mobilizing hormones. The purpose of this study was to determine the site of action of these hormones. Two possibilities were considered and tested.

The uptake of oxalate by rat liver and kidney mitochondria.

Oxalate, a metabolic end product, forms calcium oxalate deposits in the tissues under a variety of pathological conditions. In order to determine whether oxalate is able to penetrate the mitochondrial matrix, the uptake of oxalate by rat liver and kidney cortical mitochondria was characterized. Mitochondria did not swell in an iso-osmotic medium of ammonium oxalate unless a small amount of phosphate was provided.

Regulation of the uncoupling protein in brown adipose tissue.

Presumptive evidence suggests that the brown fat mitochondrial uncoupling protein, thermogenin, is involved in the mechanism of stimulation of respiration by norepinephrine in the intact tissue. Conflicting data have been reported which suggest involvement of either adenine nucleotides, or fatty acids, or long chain acyl-CoA, or protons in the physiological regulation. We measured the electrical potential gradient across the mitochondrial membrane (delta psi m) in control cells and in cells stimulated with norepinephrine, using the accumulation of lipophilic cation, tetraphenylphosphonium, as an indicator of the potential gradient.

The significance of the attachment of rat kidney glutaminase to the inner mitochondrial membrane.

The inner mitochondrial membrane of rat kidney mitochondria was altered by 0.03% Triton X-100 treatment in such a way as to render it permeable to NAD and CoA molecules without release of phosphate-dependent glutaminase. A break of linearity in the Arrhenius plot of the enzyme activity was characteristic for a conformational change of a membrane-bound enzyme.

The effect of glucagon on hepatic respiratory capacity.

Data from numerous laboratories show that mitochondria isolated from livers treated acutely with glucagon have higher rates of state 3 respiration than control mitochondria. The purpose of the present study was to learn whether this phenomenon is an isolation artifact resulting from a stabilization of the mitochondrial membrane or whether it represents a real increase in the maximal respiratory capacity of liver cells due to glucagon treatment. Electron transport was measured through different spans of the electron transport chain by using ferricyanide as an alternate electron acceptor to O2.

The effect of hormones on proton compartmentation in hepatocytes.

Liver mitochondria isolated from rats treated acutely with glucagon exhibit higher respiration-dependent H+ ion gradients across the mitochondrial inner membrane than mitochondria from control rats. It has been suggested that similar increases in mitochondrial delta pH in situ could stimulate gluconeogenesis, chiefly because the transport of pyruvate into mitochondria would increase in response to the increase in mitochondrial matrix pH. In order to determine whether the increased delta pH observed in vitro in isolated mitochondria also occurs in situ, the effect of glucagon on the pH in the cytosol and mitochondria matrix spaces of isolated hepatocytes was determined.

The purine nucleotide cycle and ammonia formation from glutamine by rat kidney slices.

To test the significance of the purine nucleotide cycle in renal ammoniagenesis, studies were conducted with rat kidney cortical slices using glutamate or glutamine labelled in the alpha-amino group with 15N. Glucose production by normal kidney slices with 2 mM-glutamine was equal to that with 3 mM-glutamate. With L-[15N]glutamate as sole substrate, one-third of the total ammonia produced by kidney slices was labelled, indicating significant deamination of glutamate or other amino acids from the cellular pool.

Effects of maleate on the content of CoA and its derivatives in rat kidney mitochondria.

Effects of maleate on the content of CoA derivatives in isolated mitochondria and in the tissues of maleate-intoxicated rats have been studied. The addition of maleate to kidney mitochondria incubated with 2-oxo-glutarate decreased CoA-SH and acid-soluble acyl-CoA concentrations while acid insoluble acyl-CoA content remained unchanged. As a result, a substantial loss (depletion) of the total CoA occurred.

Metabolism of glutamine in rat kidney mitochondria in the presence of aminooxyacetate.

1. Aminooxyacetate has no effect on respiration of rat kidney cortex mitochondria in the presence of glutamine but it inhibits respiration in the presence of glutamate to the values of endogenous respiration. 2.

Effect of extracellular pH and inhibitors on the gluconeogenesis and ammoniagenesis relationship in rat kidney cortex slices.

1. Gluconeogenesis from glutamine, fumarate, pyruvate, glutamine plus fumarate, and glutamine plus pyruvate, was generally higher at pH 7.1 than at pH 7.