[Intradermal metal deposits in an industrial worker]. / Intradermale Metalleinsprengungen bei einem Industriearbeiter.

CASE REPORT: We describe a 75-year-old patient with asymptomatic grey pigmentation on the face and fingers. He had worked over two decades in cutting high-voltage cables. The cutting procedures were performed without a face shield or protection gloves. The patient presented with gray punctate lesions beside some homogeneously stained zones. DIAGNOSTICS: Histologically, the deposits presented in the dermal tissue in a horse-shoe, oval, or splinter-like shape. The foreign body material was embedded by a few CD68-positive macrophages. Undyed histological sections were investigated via two-dimensional micro-synchrotron X-ray fluorescence analysis (SRXRF). The deposits were identified as zinc (Zn), copper (Cu), nickel (Ni), and strontium (Sr), which were strongly associated with maximal sulfur (S) concentrations. This association is presumably induced by complex binding between thiol groups and metal ions such as Zn, Ni etc. However, the iron (Fe) distribution patterns were quite different to those of Zn, Cu, or Ni. These heavy metals are major components of the metal wires that the patient worked with in his profession. CONCLUSION: To the best of our knowledge, this is the first case report in the dermatological literature of intradermal metal deposits identified via SRXRF analysis.

Quantitative trace element mapping in liver tissue from patients with Wilson`s disease determined by micro X-ray fluorescence.

AIMS: of this investigation were to quantify copper (Cu), iron (Fe) and zinc (Zn) along with sulphur (S) and phosphorus (P) in hepatocytes and connective tissue in liver section from patients with Wilson´s disease (WD) by micro Synchrotron X-ray fluorescence (µ-SRXRF). Secondly to establish two-dimensional µ-SRXRF element mappings for comparison with histologically prepared slices, and thirdly to assess whether elemental distributions are associated. METHODS: Archival liver tissues from twelve patients with end-stage cirrhosis or fulminant WD were investigated. Mutations in ATP7B have been classified before. For control seven archived normal liver tissues were investigated. µ-SRXRF measurements were performed at the DORIS III storage ring at HASYLAB/DESY (Hamburg, Germany). Two-dimensional element distribution were compared with histologically prepared slices about 20-30 µm apart from those investigated by µ-SRXRF. RESULTS: Elementary copper (Cu) could be demonstrated in all investigated liver sections simultaneously with Fe, Zn, P and S. In WD mean Cu was 20 fold increased in hepatocytes and threefold in fibrotic areas in comparison with controls. In regeneration nodules Cu was strikingly inhomogeneous distributed. Cu concentrations measured by µ-SRXRF correlated with those measured by atom absorption spectroscopy. Strong associations in their regional distribution existed between Zn and Cu or Fe and S. Moreover, differences in Cu/S were found between hepatocytes and fibrotic areas. An increase of Fe could only be documented in hepatocytes compared to fibrotic areas. With a beam size of 15 x 15 µm two-dimensional distributions of these elements are morphologically comparable with histological section with a magnification of about 25x optic microscope. CONCLUSIONS: µ-SRXRF investigations are a valuable tool for quantifying element concentrations in biological tissues and further provide 2-dimensional information of element distribution and elemental association in a biological tissues, thus speeding up basic knowledge in a synopsis with biological and clinical data.

Influence of fatty acid composition in mammalian erythrocytes on cellular aggregation.

The rheologic properties of red blood cells (RBC) are determined by humoral and cellular factors. Fatty acid composition of the RBC phospholipid bilayer is one factor influencing membrane fluidity this could affect RBC aggregation because of a higher bias of RBC deformability. The present investigation was performed to investigate a possible relationship between fatty acid composition and erythrocyte aggregation using animals with high RBC aggregation (horse and pig) and animals with immeasurable RBC aggregation (sheep). Horse and pig showed similar distribution of the four major components palmitoleic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1n9), and linoleic acid (C18:2n6). The sheep's saturated fatty acids C16:0 and C18:0 were decreased, whereas unsaturated oleic acid (C18:1n9) showed a two fold increase in comparison to horse and pig. It can be assumed that the fatty acid bilayer is a minor factor influencing erythrocyte flexibility due to its influence on membrane fluidity and therefore there might be an existing link to erythrocyte aggregation. The sheep has relatively dense erythrocytes with low cell volumes. Therefore, the absence of aggregation might be postulated to arise from geometric factors against the expected effect of unsaturated fatty acids on membrane fluidity, the higher level of unsaturated fatty acids in ovine erythrocytes over that found in horse and pig was surprising. The present result, which accords with former studies, indicates that the geometric factor given by the intracellular skeleton overrides any effect of membrane composition on aggregation in sheep.

Effects of parathyroidectomy on lead mobilization from bone in patients with primary hyperparathyroidism.

Since lead (Pb) accrued from environmental exposure accumulates in bone with a half life time between 6 and 10 years, a release of bone Pb into the circulation and/or urine (PbU) should be expected in diseases with increased bone metabolism such as hyperparathyroidism. We studied 60 patients with primary hyperparathyroidism (pHPT, 50 women, 10 men, aged 61.4 +/- 10.6 and 64.1 +/- 9.9 years, respectively) (a) before, (b) 1-6 months, and (c) 6-12 months after parathyroidectomy. Besides lead in blood (PbB) and lead in 24-h urine samples (PbU), parathyroid hormone (PTH), serum Ca2+, osteocalcin (OC), phosphate (PO4), and serum pyridinoline cross-linked telopeptide (cTP) were determined. Control data were determined in 20 healthy age-matched subjects. As expected, Ca2+ decreased after parathyroidectomy. Mean PbB in patients with pHPT was in the same range as in controls. A decrease of PbB after parathyroidectomy was found in the interval beyond 6 months. In contrast, mean PbU initially increased after surgery (3.05 +/- 1.94 vs. 4.25 +/- 2.65 microg/l, P = 0.004) and was not different beyond 6 months in comparison with preoperative values at (c). Investigating only patients with PTH < 150 ng/l, no significant PbB or PbU alterations were detected before and after parathyroidectomy. In patients with PTH > 150 ng/l, the decrease of PbB at (c) was more pronounced as was the increase of PbU at (b). In these patients, PbB and OC as well as PbB and cTP were correlated preoperatively. In conclusion, our data show that in environmentally lead-exposed (by food or by pollution) hyperparathyroid individuals, there is no hazardous PbB release from bone. The preoperative correlation between PbB and OC in pHPT patients with PTH > 150 ng/l provides evidence that in fact there is a Pb release from bone into the blood-pool by bone remodeling. The increase of PbU after parathyroidectomy is suspected to be caused by PTH-dependent Pb accumulation in the kidney, which seems to be restored with decreasing PTH. Moreover, our data confirm prior findings that bone remodeling seems to be normalized 6 months after parathyroidectomy.

Increased lead excretion correlates with desoxypyridinoline crosslinks in hyperthyroid patients.

Lead is a widespread toxic metal that accumulates predominantly in human bone. Altered bone metabolism in hyperthyroidism is characterized mainly by bone resorption. Thus, we speculated that lead excretion could be increased in hyperthyroid patients. In 12 hyperthyroid patients (43.3 +/- 16.1 years) who were not previously occupationally exposed to lead, lead concentrations in blood (PbB), spot urine samples corrected by urine creatinine (PbUs), and in 24-hour urine samples (PbU24) were determined in the hyperthyroid state and after euthyroidism had been induced by therapy. Serum osteocalcin (OC) and desoxypyridinoline crosslinks (Pyr) served as specific markers for bone metabolism. After induction of euthyroidism (duration of antithyroid therapy: mean 17.3 +/- 6.9 weeks) PbB was reduced (3.7 +/- 2.6 vs. 5.7 +/- 4.7 microg/dL, p = 0.041) as was PbUs (0.39 +/-0.27 vs. 0.61 +/- 0.32 microg/mg Cr, p = 0.005). A fourfold decrease of PbU24 was associated with a 3.3-fold decrease of Pyr, and moreover there was a significant correlation between Pyr and PbUs (r = 0.58, p = 0.047). Concentration of total triiodothyronine correlated with Pyr (r = 0.66, p = 0.018), but not with PbB or PbUs. OC showed only a tendency to be increased before antithyroid medication, and did not correlate with either thyroid hormone or Pyr. Our results indicate that in hyperthyroid patients, even when not previously exposed to lead, lead excretion is increased due to bone resorption.

Increased concentration of arachidonic acid in erythrocyte membranes in chronically lead-exposed men.

Animals intoxicated by lead present alterations in the fatty acid composition of red blood cells (RBC). Since this altered fatty acid composition of membranes may be a general reflection of lead toxicosis, we have examined 12 clinically healthy lead-exposed male subjects for fatty acid composition of RBC membranes along with blood lead, serum calcium, and serum iron concentrations. Twelve unexposed age-matched male subjects were used as controls. Significantly increased levels of arachidonic acid (AA) were found as compared to matching healthy controls in the RBC of the lead-exposed subjects. The increase of AA correlated in a dose-dependent manner with elevation in lead, and with serum iron, while a negative correlation was found between AA and serum calcium. The known ability of lead to substitute for calcium, which is essential in activating phospholipase A2 for AA release from membrane phospholipids, may be the main reason for increased AA in RBC membranes.

Increased lead excretion in hypothyroid patients after levothyroxine medication.

In a recent publication we hypothesized that increased bone metabolism induced by thyroid hormones should increase lead excretion even in lead unexposed subjects. To examine this hypothesis, 10 hypothyroid patients were investigated before and after substitution therapy with levothyroxine. After a mean of 9 wk after onset of therapy (patients were then in an euthyroid state), lead concentrations in urine (PbU) corrected by the individual creatinine in urine were increased (p = .007), while lead concentrations in blood (PbB) were slightly decreased (3.44 +/- 1.73 vs. 2.74 +/- 1.38, p = .008). Desoxypyridinoline cross-links (Pyr), a sensitive marker for bone degradation and excreted in urine, correlated with PbU (r = .64, p = .002) but not with PbB. Additionally PbU significantly correlated with serum concentrations of free circulating T3 (fT3) or free circulating T4 (fT4). Thus, we may suspect that increased lead excretion was induced by accelerated bone metabolism, since Pyr was increased after therapy (3.21 +/- 1.19 vs. 6. 10 +/- 1.81 nM/mM Cr, p < .001), too.

Neurobehavioral effects of vanadium.

It was our aim to study whether chronic exposure to vanadium reduces cognitive abilities. We investigated effects on attention, visuospatial and visuomotor functioning, reaction time, short-term memory, and prefrontal functioning. Forty-nine vanadium exposed subjects with a mean vanadium level in urine (VanU) of 14.4 micro/L and 49 controls (VanU: 0.8 microg/L) with the same socioeconomic background were investigated. Neuropsychological tests were done using a modified Wisconsin Card Sorting Test (WCST), Block Design Test (BDT), Visual Recognition Test (VRT), Simple Reaction Time (SRT), Choice Reaction (CR), Digit Symbol Substitution (DSS), and Digit Span (DS). Exposure was assessed by using the vanadium level in urine and serum. While there were significant differences in BDT and DSS, no differences were found in WCST, SRT, CR, and DS. Significant correlations existed between the vanadium levels in urine and serum and the cognitive deficits. Vanadium concentrations around 14.2 microg/L in urine reduce neurobehavioral abilities, particularly visuospatial abilities and attention.

Hemorheology in occupational lead exposure.

OBJECTIVES: The purpose of this investigation was to study hemorheological parameters in occupationally lead exposed men. MATERIAL AND METHODS: For 15 clinically healthy lead-exposed male subjects [age 34.6 (SD 8) years] the viscous (epsilon') and elastic (epsilon") components of whole blood viscosity corrected for 45% hematocrit were measured for shear rates between 1.s-1-100.s-1 at 37 degrees C. Moreover, lead concentrations in blood and urine and the delta-aminolevulinic acid dehydrase level were determined. Fifteen unexposed age-matched men were used as referents. RESULTS: The mean lead concentration in the blood and urine of the lead-exposed men was 48.7 (SD 16.2) micrograms. dl-1 and 38.8 (SD 17.1) micrograms.g creatinine-1, respectively. While epsilon" was significantly increased only at low shear rates, epsilon' was elevated throughout the investigated shear range in comparison with the values of the unexposed referents. These results are characteristic of erythrocytes with enhanced rigidity. The aggregation and filtration index of erythrocytes were significantly elevated for the lead-exposed workers. A positive correlation existed between lead in blood and epsilon' or epsilon", whereas delta -aminolevulinic acid dehydrase and epsilon' or epsilon" were inversely correlated. No differences in plasma viscosity or in lipid status could be detected. CONCLUSION: Increased blood lead concentrations can be considered an additional risk factor for vascular diseases predisposing towards microvascular occlusion.

Plasma catecholamines, atrial natriuretic peptide and blood lactate responses during upright bicycle ergometry with incremental steps adapted to individual maximal work capacity.

To assess whether hormone and metabolic responses in an upright bicycle exercise test are equivalent for subjects with different physical characteristics if test duration for reaching individual maximal work capacity (PWCmax) is standardized we investigated plasma catecholamines, human atrial natriuretic peptide (hANP) and blood lactate responses in twenty healthy sedentary subjects. Ten male (38.5 +/- 4.7 yrs) and ten female (34.5 +/- 6.4 yrs) healthy volunteers performed two ergometries, a first one with incremental steps of 25 Watts each for two minutes to determine PWCmax, and a second one with incremental steps of PWCmax/6. According to this definition a test duration of 12 min was attained for all subjects for the second ergometry. The results show that the increase of the rate pressure product (RPP) as an index of relative cardiac work is significantly different between the male and female group in the test with constant 25 Watts steps. But with the modified exercise test RPP/time-slopes are nearly identical, identicating equivalent cardiac work due to gender and body surface. Similar results are obtained for plasma catecholamines, hANP and blood lactate. Mean values did not differ in the modified exercise test between the male and female group either in the sub-maximal range or at PWCmax. In conclusion, our data suggest that in a maximal exercise test with equal test duration, and considering individual physical properties for the calculation of incremental steps hormonal and metabolic responses are equivalent. It seems that the designed, modified exercise test provides inter-individual comparisons at least for these investigated parameters. The test may be helpful if catecholamines, hANP or lactate are used as diagnostic parameters in patients.

Lead accumulation in tidemark of articular cartilage.

OBJECTIVE: Determination of the spatial distribution of the toxic element lead (Pb) and other trace elements in normal articular cartilage and subchondral bone from adult humans with no history of work-related exposure to Pb. METHODS: Four macroscopically normal femoral heads and three patellas were harvested from randomly selected forensic autopsies. All subjects died of acute illnesses, had no history of work-related exposure to Pb and had no metabolic bone disease. The elemental distribution of lead (Pb) together with zinc (Zn), strontium (Sr) and calcium (Ca) in the chondral and subchondral region was detected using high resolution synchrotron radiation induced micro X-ray fluorescence (SR mu-XRF) analysis. SR mu-XRF line scans in conventional and SR mu-XRF area scans in confocal geometry were correlated to backscattered electron (BE) images visualizing the mineralized tissue. RESULTS: In all samples, we found a highly specific accumulation of Pb in the tidemark, the transition zone between calcified and non-calcified articular cartilage. Pb fluorescence intensities in the tidemark, which is thought to be a metabolically active mineralization front, were 13-fold higher when compared to subchondral bone. Pb intensities in the subchondral region were strongly correlated with Zn, but were distinctly different from Ca and Sr. CONCLUSIONS: The finding of the highly specific accumulation of lead in the tidemark of human articular cartilage is novel. However at this point, the exact mechanisms of the local Pb accumulation as well as its clinical implications are unknown.

Functional adrenergic receptor polymorphisms and idiopathic orthostatic intolerance.

OBJECTIVES: Idiopathic orthostatic intolerance (IOI) is a common disorder that is characterized by chronic orthostatic symptoms and substantial increases in heart rate and plasma norepinephrine concentrations that are disproportionately high while standing. Several features of the syndrome, including the tachycardia, tremulousness, and exaggerated norepinephrine have been considered potentially due to hypoactive or hyperactive states of adrenergic receptors of the sympathetic nervous system. The aim of this study was therefore to ascertain whether genotypes at eight polymorphic loci within five relevant adrenergic receptor genes (alpha2A, alpha2B, alpha2C, beta1 and beta2) influence the risk for IOI. METHODS: We studied 80 young men in military service (20 patients with IOI and 60 age-matched controls). All participants underwent a tilt table test including monitoring of blood pressure, heart rate and plasma catecholamines, in the supine position and during 30 min of standing. Genotyping at the eight loci (alpha2ALys251, alpha2BDel301-303, alpha2CDel322-325, beta1Gly49, beta1Arg389, beta2Arg16, beta2Glu27, beta2Ile164) was performed in all participants. Chi-square tests of independence were used to test for associations between IOI and genotype. In addition, an association of the polymorphisms with haemodynamic variables (heart rate, supine and upright blood pressure) was ascertained using one-way variance analysis. RESULTS: For the beta1Gly49 polymorphism we found a decrease in the risk of IOI among persons who were homozygous (odds ratio, 0.88; 95% confidence interval, 0.81-0.97). In addition, we found an association between beta1Gly49 and decreased heart rate in the upright position, regardless of IOI diagnosis. There were no associations with the other studied polymorphisms and IOI. CONCLUSIONS: Our current results suggest that the beta1Gly49 polymorphism is protective for IOI. This is likely one of several common genetic loci that may represent modifiers of IOI phenotypes.

Dose dependent reduction of erythroid progenitor cells and inappropriate erythropoietin response in exposure to lead: new aspects of anaemia induced by lead.

OBJECTIVE: To determine whether haematopoietic progenitor cells and erythropoietin (EPO), which is an essential humoral stimulus for erythroid progenitor (BFU-E) cell differentiation, are affected by lead intoxication. METHODS: In male subjects chronically exposed to lead with and without anaemia, pluripotent (CFU-GEMM), BFU-E and granulocyte/macrophage (CFU-GM) progenitor cell counts in peripheral blood were measured with a modified clonal assay. Lead concentrations in blood (PbB) and urine (PbU) were measured by the atomic absorption technique, and EPO was measured with a modified radioimmunoassay. RESULTS: PbB in the subjects exposed to lead ranged from 0.796 to 4.4 mumol/l, and PbU varied between 0.033 and 0.522 mumol/l. In subjects exposed to lead with PbB > or = 2.896 mumol/l (n = 7), BFU-E cells were significantly reduced (p < 0.001) whereas the reduction in CFU-GM cells was only of borderline significance (p = 0.037) compared with the age matched controls (n = 20). The CFU-GEMM cells remained unchanged. Furthermore, BFU-E and CFU-GM cells were reduced in a dose dependent fashion, with increasing PbB or PbU, respectively. In the subjects exposed to lead EPO was in the normal range and did not increase in the presence of anaemia induced by lead. No correlations existed between EPO and PbB, PbU, or progenitor cells. CONCLUSION: The data suggest new aspects of lead induced anaemia besides the currently acknowledged shortened life span of erythrocytes and inhibition of haemoglobin synthesis. Two additional mechanisms should be considered: the reduction of BFU-E cells, and inappropriate renal EPO production in the presence of severe exposure to lead, which would lead to an inadequate maturation of BFU-E cells.

Nutritional antioxidants, red cell membrane fluidity and blood viscosity in type 1 (insulin dependent) diabetes mellitus.

The study was designed to evaluate whether the antioxidant nutrients selenium, vitamin A, and vitamin E are associated with alterations of blood viscosity in patients with insulin-dependent (Type 1) diabetes mellitus (IDDM). We assessed selenium concentrations in plasma and red blood cells (RBC), glutathione peroxidase activity in RBC, vitamin A and vitamin E, and the viscosity of whole blood and plasma in 20 patients with IDDM and 20 sex, age and body mass index-matched healthy controls. While selenium was not altered in plasma in IDDM, it was markedly decreased in RBC of IDDM (1.24 +/- 0.32 vs 0.92 +/- 0.38 mumol l-1, p = 0.006) correlating negatively with the elastic and viscous component of whole blood viscosity. Plasma viscosity increased with stage of retinopathy. Mean glutathione peroxidase activity in RBC was reduced in IDDM (5.78 +/- 0.77 vs 5.13 +/- 1.03 U gHb-1, p = 0.029). In IDDM with normal renal function (creatinine < or = 97.2 mumol l-1, no albuminuria) vitamin A was significantly reduced (1.26 +/- 0.62 vs 1.89 +/- 0.56 mumol l-1, p = 0.005). Vitamin A levels increased with impaired renal function. They strongly correlated with plasma creatinine (r = 0.86, p < 0.001) and plasma viscosity (r = 0.71, p = 0.001). However, in vitro experiments with different vitamin A plasma concentrations indicated that this particular correlation may not represent a causal one. No changes in vitamin E were found in IDDM. We conclude that reduced selenium concentrations in RBC contribute to impaired haemorheology in IDDM patients. Plasma viscosity was not affected by the plasma concentrations of vitamins A and E.

Membrane potential measurements in human oocytes.

Both maturation and fertilization of oocytes involve changes within the cell membrane as also in other cell structures. One method of documenting this phenomenon is the electrophysiological measurement of membrane potential (MP). Changes of MPs occurring coincidentally with the development of oocytes have been published previously for intervertebrates and vertebrates. In the present investigation MPs were measured in human oocytes at different stages of development. This was to prove whether the data published for animal models are also relevant in man. MPs were obtained from oocytes recovered for in vitro fertilization (IVF). This procedure produces not only the desired normal fertilized oocytes, but also immature cells, oocytes with failure of fertilization and pathologically fertilized oocytes. The results obtained show a good correlation of MP-changes during development and after fertilization with data published previously from a variety of species. In mouse and human oocytes, even absolute MP-values show a good correlation.

Kinetics of plasma cyclic GMP and atrial natriuretic peptide after intravenous, intramuscular and subcutaneous injection of 50 micrograms hANP in man.

Plasma kinetics of immunoreactive natriuretic peptide (IR-ANP) and cyclic guanosine monophosphate (cGMP) were studied after intravenous (i.v.), intramuscular (i.m.) and subcutaneous (s.c.) application of 50 micrograms human ANP (hANP) in six healthy, male volunteers. The study was single blind. Mean base-line IR-ANP value (N = 54) was 10.8 +/- 1.8 pmol/l. Five min after injection peak IR-ANP concentrations were reached i.v.: 149.5 +/- 94, i.m.: 25.6 +/- 10.8 and s.c.: 18.3 +/- 3.3 pmol/l while cGMP levels reached maximum values at 15 min or 30 min after application: i.v.: 30.6 +/- 12.1, i.m.: 19.2 +/- 8.5 and s.c.: 17.3 +/- 12.3 nmol/l with a mean base-line value of 13.2 +/- 2.1 nmol/l. The calculated corresponding areas under the IR-ANP curves (AUC) achieved about 22% bioavailability for i.m. and s.c. in comparison with the i.v. application. cGMP bioavailability was about 32%. No statistical difference was calculated between i.m. and s.c. application of 50 micrograms hANP. Changes in IR-ANP levels after i.m. and s.c. administration were not accompanied with effects on urine and electrolyte excretion while there was only a tendency in urine volume and sodium increase after i.v. administration. In conclusion after i.m. or s.c. application of hANP only a minor fraction (approximately 1/5) of IR-ANP is available in circulation in comparison with i.v. application with little or no biological effects.

Atrial natriuretic peptide release due to physical exercise in healthy persons and in cardiac patients.

Plasma levels of human atrial natriuretic peptide were determined during different stages of a symptom-limited bicycle ergometer stress test. Eight healthy persons and three patients suffering from well-defined cardiac disorders were examined. Measurements of the peptide were performed before the exercise, at 75 watts, at maximal work load, and 10 and 30 min after ceasing the exercise. In healthy persons plasma levels of the peptide increased from preexercise levels of 4-41 ng/l to 16-59 ng/l at maximal work load, but remained in the normal range (10-70 ng/l). In contrast, in the cardiac patients, levels of the peptide were up to 8-fold higher at maximal physical exertion (154-270 ng/l) than at rest (34-86 ng/l). Within a recovery period of 30 min hormone concentrations returned almost to preexercise levels.

Dissociation of hemodynamic and renal effects of i.v. alpha-hANF (99-126) in conscious calves.

The effects of i.v. human atrial natriuretic factor (alpha-hANF [99-126]) was investigated in 5 conscious calves (age 4 months, weight 94 +/- 14kg) with constant fluid (300 ml/h) and sodium intake over a period of 24 hours before and during the 3 hours of experimentation. We administered 200 micrograms, 400 micrograms and 800 micrograms ANF at hourly intervals. Immediately (+2 min) after the i.v. injection the peptide's serum-concentration rose from, basal 13 +/- 3 to 802 +/- 191 (200 micrograms), 1707 +/- 419 (400 micrograms) and 3483 +/- 878 pmol/l (800 micrograms) (p < 0.0001), respectively. Mean arterial pressure decreased from, basal, 108 +/- 18 to 85 +/- 17, 76 +/- 16 and 69 +/- 18 mmHg (p < 0.0001), and central venous pressure decreased from, basal, 5.1 +/- 3 to 1.2 +/- 1, 0.4 +/- 1 and 0.8 +/- 2 mmHg (p < 0.001). Heart rate increased from, basal, 66 +/- 5 to 84 +/- 23, 111 +/- 29 and 114 +/- 13 b/min (p < 0.001). Following the administration of ANF the urine volume decreased from, basal, 261 +/- 145 to 195 +/- 72, 121 +/- 41 and 102 +/- 33 ml/h (p < 0.0041). The urinary sodium excretion rates decreased from, basal, 50 +/- 17 to 30 +/- 13, 22 +/- 10 and 19 +/- 10 mmol/h (p < 0.007), and the potassium excretion rates decreased from, basal, 43 +/- 19 to 39 +/- 16, 26 +/- 11 and 23 +/- 10 mmol/h (p < 0.0047). Endogenous clearance of creatinine (basal: 182 +/- 30 ml/min) did not change (260 +/- 84, 218 +/- 66 and 224 +/- 76 ml/h) following i.v. ANF. Inspite of this marked fluid retention, the hematocrit, expressed as relative change, was increased by 7.5%, 11.8% and 10.4%. In 2 calves we additionally measured an increased whole blood and plasma density possibly indicating increased liquid permeation to an extravascular compartment. Thus, in calves the hemodynamic effects of ANF are comparable to those seen in man. However, the failure of ANF to stimulate diuresis and natriuresis indicates a dissociation of hemodynamic and renal effects of ANF in calves.

Improved glucose tolerance by acute vanadate but not by selenate exposure in genetically obese rats (fa/fa).

OBJECTIVE: To describe the impact of acute vanadate and selenate exposure on glucose tolerance of obese Zucker rats (fa/fa). DESIGN: Intravenous glucose tolerance tests (2.4 mmol/kg, continuously from 0 to 30 min) were performed in conscious Zucker rats exposed to a bolus-continuous infusion of sodium vanadate (2.45 mumol/h) or sodium selenate (0.90 and 2.45 mumol/h) and were compared to intraindividual control experiments with saline infusion. RESULTS: Vanadate infusion improved glucose tolerance and decreased insulin release, as shown by total areas under the curves (0-120 min: Glucose, min.mmol/l: control, 983 +/- 59 vs vanadate, 915 +/- 54, P < 0.02; Insulin min.nmol/l: control, 117.5 +/- 19.9 vs vanadate, 88.5 +/- 26.2, P < 0.01). In contrast, infusion of selenate increased glucose induced insulin release during the first phase of the IVGTT (0-60 min, incremental area under the insulin curve: by 57% and 110% for low and high selenate infusion rate, respectively) and transiently improved glucose tolerance (0-60 min, decrease of incremental area under the glucose curve: 31% and 28%, respectively). That effect of selenate was lost with progression of the experiment during the second hour of the IVGTT, when plasma glucose continued to decline slowly in control experiments, but increased in selenate exposed rats without any adequate insulin secretory response to hyperglycemia. CONCLUSION: The results demonstrate improved glucose tolerance and decreased plasma insulin concentration during acute vanadate exposure. Only a transient insulinotropic effect with improved glucose tolerance is induced during acute selenate exposure, and is followed by progressive development of hyperglycemia indicating selenate toxicity.