Growth and development of the bone mass of two strains of inbred rats.

The experiments reported in this paper were designed to gain information on the growth and development of the bone mass of the rat and to recognize genetically determined features of the growth phenomenon. The experimental model involved the study of the axial (AX, head excluded) and appendicular (AP) skeletons of two strains of inbred rats ('m' and 'e') from the 3rd to the 27th week of age. The contribution of the skeleton to body weight differed between strains ('m' greater than 'e'). The development of the skeleton was in phase with body growth (peak growth rate = 7th week of age). The AP skeleton of these strains of rats differed in the kinetics of matrix mineralization ('m' faster than 'e') and in the ash/matrix ratio of adult animals ('m' greater than 'e'). The AX skeleton, on the other hand, showed a constant ash/matrix ratio from the 4th to the 27th week of age, without significant differences between strains. The anatomical volume of the femur was found to differ significantly between strains at an earlier age (4th week) than its dry weight (7th week). The AP and AX skeleton of 'e' rats mature simultaneously attaining their peak calcium mass at 36 weeks of age. The maturation of the AP and AX skeletons of 'm' rats, on the other hand, are dissociated and attain full maturity at approximately 39 and 57 weeks, respectively. The curves of specific growth rates (g of Ca (or matrix) per week/g of skeletal Ca (or matrix] of the AP and AX skeletons indicate that there exist separate metabolic controls for the growth of Ca and matrix masses. Absolute measurements (Ca, organic matrix, ash or total dry weights, bone volume) unambiguously established that 'm' rats have greater bone mass than 'e' ones. Relative measurements favoured 'm' (ash/matrix ratio of AP skeleton), 'e' (femoral weight/volume ratio, percentage of metaphyseal trabecular bone volume) or gave no significant differences between strains (ash/matrix ratio of AX skeleton). These results indicate that the AP and AX skeletons have important metabolic differences and that their growth and development are under genetic control.

Comparative study of the effect of sodium fluoride and sodium monofluorophosphate on glucose homeostasis in the rat.

The effect of acute and chronic administration of sodium fluoride (NaF) or sodium monofluorophosphate (MFP) on the glucose homeostasis of the rat are compared. The oral administration of a single dose of 40 mumol/100 g b.w. of either compound produced similar increases in plasma glucose (up to 1.8 g/l) and diffusible fluoride (up to 130 mumol/l). In long-term experiments (three months of duration), treatment with NaF (a 5 mmol/l solution as the water supply) produced, in the first month of experiment, abnormal glucose tolerance tests and increased plasma diffusible fluoride levels (range: 2-12 mumol/l). Treatment with MFP, on the other hand, did not affect glucose homeostasis; plasma diffusible fluoride was always below 2 mumol/l. The results of these experiments indicate that glucose homeostasis is affected when plasma diffusible fluoride exceeds 5 mumol/l. The basal and glucose-stimulated insulin secretion of isolated Langerhans rat islets (incubated with solutions containing 2, 5, 10 and 20 mumol/l NaF) was significantly inhibited by 5 to 20 mumol/l fluoride. No effect was observed under similar conditions with MFP at concentrations of 2, 5, 10, 20 and 50 mumol/l.

Measurement of total and diffusible serum fluoride.

This article describes a technique for the measurement of total and diffusible F content of serum, at clinical significant concentrations of F (1-10 microM). The proposed procedure avoids the interference of unknown serum components with the ion-specific electrode. Sample F is concentrated fivefold through distillation of hydrofluoric acid (Taves' method). Ionic fluoride is presented to the electrode in a simple solution at concentrations within the linear response of the electrode. Average recoveries of F from serum or its ultrafiltrate were 96+/-7% (21%) and 97+/-12% (53%) (mean+/-SEM [CV]), respectively. With four replicates of each sample, the technique produce within-run standard deviations of 0.6 microM and 2.2 microM at 1 and 10 microM F, respectively. Total precision assessment gave standard deviations of 0.6 microM and 2.6 microM at 1 and 10 microM F, respectively. The fasting serum F levels of normal climacteric women, 45 to 65 years, showed an asymmetric distribution. The data obtained started at the detection limit of the technique (0.1 mM). The 75 percentile was 1.85 microM for total and 0.5 microM for diffusible F. In patients (n = 25) treated with NaF (30 mg F/day) the fasting levels of total serum F (4.5 +/-1.7 microM) did not differ from those of diffusible F (4.2+/-1.5 microM). In patients (n = 50) treated with sodium monofluorophosphate (15 mg F/day) the fasting levels of total and diffusible serum F were 6.5+/-1.7 microM and 0.5+/-0.03 microM, respectively. In conclusion, this paper establishes the presence of two fractions of serum fluorine: diffusible and nondiffusible (or protein bound) and describes a technique for their clinical estimation. In untreated subjects and in patients receiving NaF, the former fraction contains ionic fluoride. In patients treated with MFP, diffusible serum fluorine is composed by ionic fluoride and low molecular weight, peptide-bound, acid-labile fluorine.

Pharmacokinetic differences between sodium fluoride and sodium monofluorophosphate and comparative bone mass increasing activity of both compounds in the rat.

After the administration of an oral dose of 80 mumol/l of NaF (CAS 7681-49-4) to rats, the area under the curve of total plasma fluoride equals 10,200 mumol.min/l. After an oral dose of 80 mumol of monofluorophosphate (MFP/CAS 10,163-15-2), two forms of fluoride appear in plasma: protein-bound MFP and diffusible fluoride. The areas under the curve of total (protein-bound + diffusible) and diffusible fluoride equal 22,200 and 8,850 mumol.min/l, respectively. The activity of MFP for increasing the bone mass of the rat was assessed with NaF as the standard. The animals were treated chronically for 100 days since weaning with food ad libitum and 5 mmol/l NaF, 5 or 2.5 mmol/l MFP solutions as the water supply. The effect obtained with 2.5 mmol/l MFP was similar to that produced by 5 mmol/l NaF, indicating a potency ratio MFP is twice as active as NaF.

Growth and development of bone mass in untreated alloxan diabetic rats. Effects of collagen glycosylation and parathyroid activity on bone turnover.

Body and skeletal growth and development were studied in alloxan-treated and age-matched control rats, between 3 and 23 weeks of age. For both groups the growth of the skeletal and body weights were in phase, with a maximum at 7 weeks of age. The growth data was assessed according to Parks' theory of feeding and growth. Alloxan-treated rats showed an important reduction in body and bone mass, with a greater impact on soft tissues. As expected, the asymptotic body and skeletal weights were reduced respect to controls. The time needed to attain 63% of mature food intake (Brody's 'time constant') was also reduced, indicating that maturation occurred at an earlier age than controls. The diabetic state is characterized by a reduced food conversion efficiency. Despite hyperfagia, alloxan-treated rats showed circa one-half the body and skeletal weights of age-matched controls. The following adverse effects of alloxan diabetes on bone tissue were observed: (a) a decrease in trabecular bone volume (femoral metaphyses) and cortical width (femoral diaphyses), (b) increased bone collagen glycosylation as a function of extracellular glucose concentration, (c) increased resistance of bone collagen to collagenase hydrolysis, (d) decreased rate of bone resorption except under strongly stimulated parathyroid function, (d) significantly lower ashes/bone matrix ratio in diabetic rats with more than 10 weeks of diabetes, and (e) no histological evidence of osteomalacia.