The double isotope tracer method is a reliable measure of fractional zinc absorption.
Explore the source record for details and available documents.
Feces↗
Biomedical subjects
N M Lowe
Publications and source records attributed to N M Lowe.
A compartmental model of zinc metabolism in healthy women using oral and intravenous stable isotope tracers.
A mathematical model of zinc metabolism in six healthy women (average age: 30 +/- 11 y) was developed by using stable isotopes of zinc. After equilibration on a constant diet containing 7.0 mg Zn/d, an oral tracer highly enriched in 67Zn and an intravenous tracer highly enriched in 70Zn were administered simultaneously. Multiple plasma and 24-h urine samples were collected for the next 7 d with complete fecal collections for 11 d. Tracer-trace ratios in plasma, urine, and feces were calculated from isotope ratios of 67Zn to 66Zn and 70Zn to 66Zn measured by using inductively coupled plasma-mass spectrometry. An a priori identifiable model composed of seven compartments was developed to describe the kinetics of both tracers as well as that of naturally occurring zinc. The parameters of the model were fitted to the data by using the SAAM-CONSAM modeling software and were estimated with good precision. Several important, not directly measurable zinc variables were estimated (mean +/- SEM) from the model including the fractional absorption from the gastrointestinal tract (0.279 +/- 0.043), the rates of endogenous secretion (2.79 +/- 0.49 mg/d) and excretion (2.01 +/- 0.35 mg/d), the fractional turnover rate of the plasma pool (131 +/- 20/d), and the sizes (7.2 +/- 1.2 and 77.1 +/- 6.4 mg) and fractional turnover rates (22.3 +/- 7.1 and 1.49 +/- 0.18/d) of the fast and slow tissue pools equilibrating with the plasma, respectively.
Administration, Oral↗
Pets and immunocompromised persons.
Explore the source record for details and available documents.
Animals↗
A stable isotope study of zinc kinetics in Irish setters with gluten-sensitive enteropathy.
The short-term kinetics of Zn turnover were studied in Irish setters with gluten-sensitive enteropathy and control dogs following intravenous injection of 0.25 mg 96.5% enriched 70ZnCl2. The 70Zn enrichment of serum was found closely to obey two-compartment kinetics and the derived two-compartment decay equation was used to calculate the size and turnover of the two initial rapidly exchanging pools of body Zn. In normal Irish setters isotopic Zn initially equilibrates with a pool (a) of size 1.27 (SD 0.46) mumol/kg and then with a second pool (b) of size 6.83 (SD 1.72) mumol/kg. The fractional turnover of pool (b) was approximately one eighth that of pool (a). Enteropathic dogs showed no reduction in the size of either rapidly exchangeable Zn pool, reduction in serum Zn concentration or abnormality in Zn balance and hence these results do not support the possibility of an underlying Zn deficiency in this disorder.
Animals↗
Dantrolene sodium protects against experimental ischemia and reperfusion damage to skeletal muscle.
The effect of 4 hours of ischemia followed by reperfusion for 1 hour has been studied in fully anesthetized rabbits. Muscles from the limb subjected to ischemia and reperfusion showed considerable ultrastructural damage, although the distribution of damage between muscles was not uniform (anterior tibialis > soleus > quadriceps). Damage to the muscle was associated with a significant increase in the concentration of some indicators of free radical-mediated processes (thiobarbituric acid-reactive substances and diene conjugates), although others (glutathione and protein sulfhydryl groups) were unchanged. Reperfused muscles also showed considerable changes in their calcium and sodium contents. Treatment of animals with dantrolene sodium (4 mg/hr) throughout the periods of ischemia and reperfusion was found to preserve the ultrastructural appearance of quadriceps, soleus and anterior tibialis muscles. No effect of dantrolene sodium on indicators of free radical activity or muscle cation content was seen.
Animals↗
Studies of human zinc kinetics using the stable isotope 70Zn.
1. The short-term (120 min) kinetics of Zn turnover has been studied in control subjects and patients with alcoholic liver disease after intravenous injection of 0.5 mg of 96.5% enriched 70ZnCl2. 2. The 70Zn enrichment of plasma was found closely to obey two-compartment kinetics and the derived two-component decay equation has been used to calculate the size and turnover of the initial two rapidly exchanging pools of body Zn. 3. In normal subjects isotopic Zn appears initially to equilibrate with the whole of the plasma Zn which comprises the first metabolic compartment, pool a. This has a size of 0.72 +/- 0.1 mumol/kg. 70Zn equilibration then occurs with a second compartment, pool b, consistent with a rapidly exchanging liver Zn pool of size 3.60 +/- 0.93 mumol/kg. The fractional turnover rate of pool b was found to be fivefold slower than that of pool a. 4. In the alcoholic group an expansion of pool a was observed (1.63 +/- 0.39 mumol/kg), but the size of the second pool was not significantly different from that of control subjects (5.55 +/- 1.0 mumol/kg), although its fractional turnover was significantly increased (Kab: control subjects, 0.018 +/- 0.002 min-1, alcoholic patients, 0.031 +/- 0.006 min-1). 5. These data therefore demonstrate that kinetic studies using stable isotopes of Zn can provide novel information on exchangeable Zn pools in man, but provide no support for the possibility of an underlying Zn depletion in patients with alcoholic liver disease.
Adult↗
Plasma 65Zn kinetics in the rat.
The amount of 65Zn in the plasma of rats after intravenous injection was found to decline following closely two-compartment kinetics over a period of 90 min. Comparative analysis of the amount of 65Zn present in the two kinetic pools at various time-intervals post-injection with the actual physiological location of the 65Zn, revealed that the initial pool (Qa) is primarily the blood plasma, while the second pool (Qb) is primarily within the liver. The plasma Zn concentration and Qa were both found to fall reproducibly during Zn depletion, whereas Qa and Qb increased following injection of Escherichia coli endotoxin in contrast to the decline in plasma Zn concentration. Further investigation of the nature of Qb indicates that it represents in part a metabolic pool within the liver which varies substantially in response to Zn status in a manner similar to metallothionein.
Animals↗