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Biomedical subjects

W R Robertson

Publications and source records attributed to W R Robertson.

At least 73 records · Page 4Linked to original sources
PubMed1991

Inhibition of protein kinase C by staurosporine increases estrogen secretion by rat Sertoli cells.

We have examined the effect of inhibition of protein kinase C activity by staurosporine on estradiol secretion by Sertoli cells isolated from 8-10 days old rats. Staurosporine lead to a dose-related increase in estradiol secretion independent of FSH, such that with 100 nmol/l staurosporine basal estradiol levels increased 10-fold. The maximal response seen with staurosporine alone (100 nmol/l) or in combination with FSH (0.4-8 IU/l) was similar to that seen with a saturating dose of FSH (8 IU/l). There was no evidence of synergy between FSH and staurosporine. Activation of protein kinase C by phorbol 12,13 dibutyrate (10(-7) mol/l) resulted in a 53-74% inhibition of estradiol production provoked by FSH (8 IU/l), staurosporine (5-100 nmol/l) or staurosporine in combination with FSH. Staurosporine (5-100 nmol/l), in the absence or presence of FSH, was unable to overcome inhibition of estradiol secretion by phorbol ester, indicating the presence of at least two independent binding sites on protein kinase C for these molecules. Forskolin (1 mumol/l)- and dibutyryl cAMP (1 mmol/l)-stimulated estradiol secretion was inhibited by 31 +/- 5% and 64 +/- 5% respectively, by phorbol 12,13 dibutyrate (10(-7) mol/l). We conclude that FSH-induced estradiol secretion in immature rat Sertoli cells is affected by protein kinase C activity.

Alkaloids↗
PubMed1991

Tri-iodothyronine increases intra-cellular calcium levels in single rat myocytes.

We have studied the effects of acute administration of triiodothyronine (T3) on cytosolic free calcium levels [Ca2+]i in single rat myocytes microinjected with aequorin. Ventricular myocytes were isolated by perfusing rat hearts with collagenase, and healthy, rod-shaped cells were injected to less than 1% of their volume with aequorin. The photons emitted from single cells were measured and a conversion to [Ca2+]i made on the basis of an in vitro calibration after the remaining aequorin had been discharged by cell lysis. Only cells that depolarized reversibly (showing elevated [Ca2+]i levels) when superfused with 80 mM KCl, and which gave a substantial signal on lysis with distilled water were used. The [Ca2+]i rose from a resting value of 150 +/- 56 nM (mean +/- SD, n = 14) by 127 +/- 47 nM on depolarization with 80 mM KCl. Application of T3 (1-100 nM) led to an increase (P less than 0.05) in [Ca2+]i (mean amplitude of 152 +/- 35 nM) before returning to baseline. The median duration of these events was 10 min (range = 1.4-34.4 min). The time to response was shorter when 100 nM T3 was applied (median and range; 6.8, 0-14 min) than when 1 nM T3 was used (16, 7.0-56.1 min) (P less than 0.05). To conclude, physiological concentrations of thyroid hormones caused rapid but transient stimulation of [Ca2+]i in single rat myocytes.

Aequorin↗
PubMed1990

Mitochondrial alpha-glycerol phosphate dehydrogenase activity in IIA fibres of the rat lateral gastrocnemius muscle; the effect of Ca2+ and ATP.

Mitochondrial alpha-glycerol phosphate dehydrogenase is an important enzyme, but it is difficult to extract and purify. We have measured the activity of this enzyme in single type IIA skeletal muscle fibres under initial rate conditions by microdensitometry of the formazan reaction product. The Km (1.6 mM) for the substrate (L-alpha-glycerol phosphate) was lower than reported for the extracted enzyme. Further, at low substrate concentrations (3 mM), the enzyme was allosterically activated by free Ca2+ concentrations of 1 microM or greater, and half-maximal stimulation occurred at 0.3 microM free Ca2+. In the absence of Ca2+, there was negative cooperativity of substrate binding with a Hill constant of 0.57, but no cooperativity occurred in the presence of calcium. ATP (10 mM) inhibited enzyme activity in the presence of Ca2+ but not in its absence.

Adenosine Triphosphate↗
PubMed1990

Testosterone reduces the bioactivity of luteinizing hormone (LH) in man.

The effect of testosterone on LH bioactivity was investigated in six adult men (aged 40-56 years) with primary hypogonadism. Two men received a 400 mg testosterone implant, another two 800 mg, and the final two patients received both doses in consecutive courses separated by at least 4 weeks. Plasma samples, obtained before and at 1, 2, 4, 8, 16 and 24 weeks after treatment, were analysed for bioactive LH by the mouse Leydig cell bioassay, and immunoreactive LH and testosterone (T) by standard radioimmunoassays. The bioactive to immunoreactive (B:I) LH ratio, an index of LH biopotency, was calculated and the results compared with those from a group (n = 17) of healthy adult men. Before treatment, both bioactive and immunoreactive LH levels in the patients were higher and T levels lower than in the normal men (P less than 0.001). The mean +/- SD B:I LH ratio (3.5 +/- 0.6) in the patients was greater (P less than 0.05) than in the controls (2.7 +/- 0.7), indicating that in primary testicular failure, increased amounts of LH with enhanced bioactivity are secreted. Following T administration, a dose-related increase in circulating T and a reciprocal decrease in LH levels was observed between 1 and 16 weeks of treatment. However, there was a more pronounced decline in bioactive rather than immunoreactive LH levels, so that the B:I LH ratios decreased (P less than 0.001) from basal values after treatment. There was a negative correlation (r = -0.82, P less than 0.001) between circulating T levels and B:I LH ratios; the stronger the feedback signal, the lower the B:I LH ratio. It is concluded that testosterone negative feedback modifies not only the quantity but also the biological quality of secreted LH.

Adult↗
PubMed1990

The effect of danazol and the LHRH agonist analogue goserelin (Zoladex) on the biological activity of luteinizing hormone in women with endometriosis.

In an attempt to determine whether the suppression in oestradiol levels caused by danazol is due to an effect on the hypothalamic-pituitary axis, we compared the endocrine effects of danazol with those of the LHRH (GnRH) agonist analogue goserelin. Serum levels of immunoreactive LH (I-LH), FSH, 17 beta-oestradiol (E2) and bioactive LH (B-LH) (using a mouse Leydig cell bioassay), were measured in ten and 20 women with endometriosis treated with danazol and goserelin, respectively. I-LH was measured both by radioimmunoassay (RIA) and immunoradiometric assay (IRMA). During 6 months of treatment with 600 mg of danazol daily, mean serum E2 decreased (P less than 0.05) to levels near the upper limit of the post-menopausal range (to a mean (and 95% confidence interval of the mean) of 117 (65-169) pmol/l) whereas FSH, I-LH (both by RIA and IRMA) and B-LH levels were not significantly altered. During 6 months of treatment with monthly depot injections of 3.6 mg goserelin, mean serum E2 decreased (P less than 0.001) to well within the post-menopausal range (to 23 (18-28) pmol/l). The mean FSH, I-LH and B-LH levels also decreased (P less than 0.05) during therapy with goserelin (from 3.9 (3.1-4.7) to 2.0 (1.6-2.4) IU/l for FSH, from 5.3 (4.5-6.1) to 1.9 (1.7-2.1) IU/l for RIA-LH, from 2.9 (2.5-3.3) to less than 0.5 (less than 0.5) IU/l for IRMA-LH and from 9.1 (7.1-11.1) to 2.9 (2.6-3.2) IU/l for B-LH).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Luteinizing hormone pulsatility in men with damage to the germinal epithelium.

Bioactive-LH (B-LH) was measured in plasma by in-vitro bioassay and immunoactive-LH (I-LH) by immunoassay at 10 min intervals for 6 h in five men after standard chemotherapy for Hodgkin's disease. Eleven normal men acted as controls. Follicle-stimulating hormone (FSH) was markedly raised in the treated patients (mean +/- SEM; 12.8 +/- 2.8 vs. 2.7 +/- 0.4 IU l-1, P less than 0.006) reflecting damage to the germinal epithelium. Bioactive (27.4 +/- 2.8 vs. 12.9 +/- 1.3 IU l-1) and I-LH (9.6 +/- 2.0 vs. 4.9 +/- 0.4 IU l-1) were elevated (P less than 0.006) in the patient group whilst testosterone levels (24.0 +/- 3.8 vs. 19.6 +/- 2.4 nmol l-1) were normal. The testosterone I-LH ratio, a putative index of Leydig cell dysfunction, was negatively correlated with FSH levels (r = -0.85, P less than 0.02). Bioactive and I-LH pulse peak amplitude were elevated, as were pulse maxima (P less than 0.05). In contrast, B-LH pulse frequency was similar between the patients (2 pulses per 6 h) and controls (median 2, range 1-3 pulses per 6 h) as was the I-LH pulse frequency (median 2, 1-2 pulses per 6 h in both groups). The mean B:I LH ratios were similar (2.94 +/- 0.09 vs. 2.63 +/- 0.14) in both groups, although the inter-pulse B:I ratio was increased (P less than 0.007) in the patient group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Changes in plasma inhibin levels following pulsatile gonadotrophin-releasing hormone therapy in a man with idiopathic hypogonadotrophic hypogonadism.

Changes in circulating inhibin levels were related to changes in testosterone (T) and the gonadotrophins luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in a hypogonadotrophic hypogonadal man before and during pulsatile gonadotrophin-releasing hormone therapy which resulted in normal spermatogenesis. Before treatment, the plasma inhibin levels in the patient (210 +/- 50 U/l; mean +/- SD of four samples) were lower than in normal controls (552 +/- 150 U/l; p less than 0.01), as were T (1.1 nmol/l) and gonadotrophin (less than 1.0 IU/l) levels. Within 1 week of gonadotrophin-releasing hormone treatment, plasma LH (14.1 +/- 0.7 IU/l) and FSH (14.4 +/- 0.6 IU/l) reached supraphysiological levels. In response, T and inhibin concentrations increased progressively to reach high normal levels (27.7 +/- 1.6 nmol/l and 609 +/- 140 U/l) at 4 weeks, by which time the gonadotrophin levels stared to decline and gradually returned to the normal range between 12 and 24 weeks of treatment. There was a concomitant decrease in T and inhibin levels which remained within the normal range. The decline in the FSH level following the rise in testicular hormones was earlier and steeper than that of LH (37.5% decrease at 4 weeks vs. 30.4% at 12 weeks), suggesting that T and inhibin may act together to inhibit pituitary FSH secretion as opposed to LH secretion which is primarily controlled by T. It is concluded that, in man, during maturation of the pituitary-testicular axis, changes in circulating inhibin parallel those of T, and quantitatively normal inhibin secretion is dependent on gonadotrophin stimulation. FSH secretion may be regulated through negative feedback control, by both T and inhibin.

Adult↗
PubMed1990

Pulsatile bioactive luteinizing hormone secretion in men with chronic renal failure and following renal transplantation.

We have measured plasma luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (To) by radioimmunoassay (RIA) and bioactive LH (B-LH) by in vitro bioassay at 10-min intervals over 6 h in men treated by haemodialysis for renal failure and in men after renal transplantation. Eleven normal male volunteers acted as controls. Immunoreactive LH (I-LH) and FSH levels were elevated (p less than 0.03) in uraemia (mean +/- SE; 10.0 +/- 1.0 and 4.6 +/- 0.7 IU/l for LH and FSH, respectively) and following renal transplantation (8.1 +/- 1.2 and 5.3 +/- 0.5 IU/l) compared to controls (C) 4.9 +/- 0.5 and 2.7 +/- 0.4 IU/l) whereas B-LH [17.3 +/- 2.5, 14.8 +/- 1.8 and 12.9 +/- 1.3 IU/l in dialysis (D), transplant (T) and C groups, respectively] levels were normal. Prolactin levels were elevated (p less than 0.03) in the D group (median 348, range 162-1,780 mU/l) compared to the T group (161, 91-206 mU/l) and controls (163, 124-312 mU/l) whereas total To levels (mean +/- SE; 17.3 +/- 4.8, 15.5 +/- 1.3 and 19.6 +/- 2.1 nmol/l in the D, T and C groups, respectively) were similar as was the free To index. B-LH (median frequency, 2 and range 1-3 pulses/6 h) and I-LH (median frequency, 2 and range 1-2 pulses/6 h) was pulsatile in all the C group but B- and I-LH pulses were absent in 2 of the 5 subjects treated by dialysis. Following renal transplantation B-LH pulses were detected in all subjects, whilst I-LH pulses were absent in 1 subject.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

ACTH adrenal cell bioassay: improved sensitivity (12 ng/L) achieved by immunoextraction of ACTH from human plasma by a monoclonal antibody.

We have previously reported a bioassay for human plasma ACTH based upon trypsin dispersed guinea-pig adrenal cells which was sensitive to 100 ng/L ACTH in unextracted human plasma when measured against human pituitary ACTH (1-39) standard 74/555. We now present a bioassay of increased sensitivity (12 ng/L) which incorporates three major changes. The trypsin/trypsin inhibitor step in the cell dispersion protocol has been replaced with collagenase, donor calf serum (3%) has been incorporated into the standard curve and ACTH has been extracted from human plasma and dilutions of standard hormone by a sephacryl bound monoclonal antibody (2A3) directed towards the 25-39 sequence. The extracted standard curve has a detection limit of 6 ng/L and the cells can tolerate up to 50% plasma equivalent concentration. Thus, the improved assay has a detection limit of 12 ng/L ACTH in plasma. The assay can now measure bioactive plasma ACTH levels reliably in the normal range.

Adrenal Glands↗
PubMed1990

The pulsatile secretion of bioactive luteinising hormone in normal adult men.

We have studied bioactive and immunoreactive LH pulsatility in 11 normal men. The temporal relationship of plasma LH, testosterone, and FSH were also investigated. Blood samples were taken at 10-minute intervals for 6 h and bioactive LH levels were determined using an in vitro mouse Leydig cell bioassay. Testosterone, LH and FSH were determined by standard radioimmunoassay. Twenty-two bioactive LH pulses were detected (amplitude 8.5 +/- 4.9 IU/l, mean +/- SD) with a frequency of 2 +/- 0.8/6 h compared with only 18 immunoreactive LH pulses (amplitude of 3.6 +/- 1.8 IU/l) and a frequency of 1.6 +/- 0.5/6 h. Bioactive:immunoreactive LH ratios increased (p less than 0.01) from the preceding pulse nadirs (2.26, range 1.66-4.28) to the pulse peaks (2.71, range 1.99-4.67). Twenty FSH pulses (seen in all but one subject) of low amplitude (0.7 +/- 0.6, median 0.5 IU/l) were also present. There was a close temporal relationship between testosterone and FSH secretion with bioactive and immunoreactive LH pulses with lags of 30-60 and 0 min, respectively. We conclude that immunoreactive LH pulses are discordant from bioactive LH pulses in 18% of occasions. Further, the mean amplitude of bioactive episodes were approximately 2.6 times greater than that of immunoreactive episodes, whereas interpulse period and pulse duration were similar. The increase in bioactive:immunoreactive ratio at pulse peaks may indicate that in normal men LH pulses are enriched with a more biopotent form of the molecule.

Adult↗
PubMed1989

The effect of some antiprostatic steroids upon cortisol production by guinea-pig adrenal cells stimulated by ACTH.

The antiprostatic steroids 6-methylene-4-pregnene-3,20-dione (6-MP) (I), 17-alpha-acetoxy-6, 16-dimethylene-4-pregnene-3,20-dione (II), and melengestrol acetate (MGA) (III) were incubated with guinea-pig adrenal cells, both alone and maximally stimulated with ACTH. Cortisol output was then measured by RIA. Increased cortisol-like secretion was obtained with 6-MP in the absence of ACTH. In the presence of ACTH, cortisol-like steroid secretion was the sum of that seen with ACTH and 6-MP alone. It follows that 6-MP stimulates in vitro a cortisol-like steroid cross reacting with the cortisol antibody by a mechanism that by-passes ACTH. Steroid (II) weakly inhibited cortisol output. MGA, in contrast, proved to be a strong inhibitor of cortisol output (ID50 of 2.3 mumol/l). Its site of action was established by adding it to adrenal cells incubated with precursor steroids on the cortisol pathway. Conversion of 3 beta-hydroxysteroids to cortisol was inhibited whereas conversion of 3-keto steroids was not affected. It follows that MGA inhibits 3 beta-hydroxysteroid dehydrogenase.

3-Hydroxysteroid Dehydrogenases↗
PubMed1989

The effect of tartrate on bone cell acid phosphatase activity: a quantitative cytochemical study.

Tartrate-resistant acid phosphatase activity (TRAPase) is widely used as a cytochemical marker to distinguish osteoclasts from macrophages and other related cell types. The degree of tartrate resistance, however, may depend on which reaction methods, tissues, or species are used. To investigate this further, we have measured the amount of cytochemical reaction product by microdensitometry. We compared osteoclast acid phosphatase (APase) activity in fresh frozen sections of neonatal rat calvaria using two different reaction methods; one is commonly employed for qualitative histochemistry and includes alpha naphthyl phosphate as substrate, simultaneous coupling to the chromagen Fast Garnet, and a 30-minute reaction time (method A). The other may be used to measure enzyme reaction rates in cells in situ and employs conditions suitable for initial velocity kinetics, namely naphthol-ASBI phosphate as substrate, post coupling to Fast Garnet, and a 2-minute reaction time. Although enzyme reaction rates differed greatly between the two methods, significant inhibition of APase activity by tartrate was observed in calvarial osteoclasts (69% and 59% with methods A and B, respectively), osteoblasts, and spleen macrophages. Using method B, mouse calvarial osteoclasts had similar APase activity to that seen in the rat. Tartrate produced little inhibition in these mouse cells, in contrast to the observations made with rat tissue, but murine spleen macrophages were significantly tartrate sensitive (40% inhibition with tartrate). On this basis, conclusions regarding the cell specificity of TRAPase should be treated cautiously.

Acid Phosphatase↗
PubMed1989

Acute in vitro thyrotropin regulation of lysosomal enzyme activity in the thyroid follicular cell.

The acute effect of a physiological concentration (1 mU/l) of thyrotropin (TSH) on the activity of four lysosomal enzymes in the thyroid follicular lining cell has been studied by quantitative cytochemical techniques. N-acetyl-beta-glucosaminidase (NAG) activity was increased by 14% after 10 min TSH stimulation and NAG and beta-galactosidase activities were increased by 24% and 25% respectively (P less than 0.05) after 20 min stimulation and by 40% and 45% (P less than 0.05) respectively after 30 min stimulation with TSH, indicating an early processing of these carbohydrate residues in thyroglobulin. Acid phosphatase activity, an acid hydrolase unrelated to the hydrolysis of thyroglobulin, was unchanged 30 min after TSH stimulation. Leucyl-beta-naphthylaminidase (LNA) activity changed biphasically with peak activities of 7 and 25 min possibly representing an early fusion of endocytotic vesicles and lysosomes and later the release process of the thyroid hormones. The changes in LNA activity and thus membrane permeability were not reflected in the other enzyme activities studied. This may indicate that the TSH regulation of lysosomal enzyme activities could be independent to the endocytotic process, which is known to involve fusion of lysosomes and endocytotic vesicles. In conclusion we have demonstrated for the first time with physiological concentrations of TSH a specific acute regulation of some lysosomal enzyme activities which may be involved in thyroglobulin processing. Further, these effects may be independent of the changes in lysosomal membrane permeability due to formation of secondary lysosomes.

Acetylglucosaminidase↗
PubMed1989

Quantitative and qualitative changes in LH secretion following pulsatile GnRH therapy in a man with idiopathic hypogonadotrophic hypogonadism.

The pattern of bioactive and immunoreactive LH secretion before and during pulsatile GnRH therapy (18 micrograms/90 min) in a hypogonadotrophic hypogonadal male has been studied. Before treatment the patient was azoospermic and had low testosterone (1.2 nmol/l) with low and apulsatile immunoreactive LH (1.9 +/- 0.2 IU/l) and FSH (1.4 +/- 1.9 IU/l) levels. There was no detectable LH bioactivity. During the first 24 h of GnRH therapy there was a small increase in immunoreactive (5.4 +/- 0.8 IU/l) and bioactive (6.7 +/- 1.3 IU/l) LH, with an irregular pattern and little effect on testosterone production (2.2 nmol/l). Within 1 week of treatment both bioactive (30.5 +/- 6.8 IU/l) and immunoreactive (13.6 +/- 1.5 IU/l) LH levels were above the normal range and the pattern of secretion was pulsatile. The bioactive to immunoreactive (B:I) LH ratios within the pulses (2.6 +/- 0.3) were higher (P less than 0.01) than between pulses (1.97 +/- 0.1) and the testosterone concentration (17.8 +/- 2.1 nmol/l) was now normal. At one month LH secretion was similar and testosterone pulses of high amplitude were evident corresponding to high-amplitude bioactive LH pulses. By 3 months mature spermatozoa (1.3 x 10(6)/ml) were seen in the patient's semen. The pattern of LH secretion was pulsatile but the levels of bioactive (13.1 +/- 3.6 IU/l) and immunoreactive (9.5 +/- 1.3 IU/l) LH decreased towards the normal range reflecting maturation of the testicular feedback control at the pituitary level. This effect was more pronounced on bioactive rather than immunoreactive LH secretion (57% vs 32% relative decrease). At 6 months LH levels were similar and the sperm count was normal (34 x 10(6)/ml).

Adult↗
PubMed1989

Assessment of the bioactivity of human and bovine thyrotrophin preparations using a porcine thyroid cell bioassay.

The biopotency of six preparations of thyrotrophin (TSH) has been compared in a highly sensitive in vitro porcine thyroid cell bioassay using iodide uptake as an endpoint. Three of these preparations were of human origin and three derived from bovine pituitary tissue. One human TSH preparation, the 2nd International Reference Preparation, 80/558, was used to calibrate the other five. The log dose-log response curves for all preparations were sigmoidal in shape. For the purpose of evaluation the central linear portions of the curves were compared. With all preparations the slopes in this region were very similar. The relative biopotencies of the bovine preparations (unit:unit) were at least five times those of the human standards when measured using the porcine thyroid cell bioassay. These findings emphasise the need to control the TSH standards employed in a variety of bioassays, particularly those used for between-laboratory comparison.

Animals↗
PubMed1988

Antibody that blocks stimulation of cortisol secretion by adrenocorticotrophic hormone in Addison's disease.

To investigate whether Addison's disease may in some cases be due to the blocking of adrenocorticotrophic hormone's action at the adrenal cortex by antibodies IgG isolated from a woman with Addison's disease associated with the autoimmune polyglandular syndrome type I was studied. Its effects on guinea pig adrenal cells in vitro were investigated and compared with those of IgG from three normal subjects and IgG obtained commercially. IgG from the patient inhibited the stimulation of cortisol secretion by adrenocorticotrophic hormone by 77 (SD 2)% and 57 (12)% at concentrations of 0.5 and 0.05 g/l, respectively; IgG prepared five months after she had started treatment with replacement steroids inhibited cortisol secretion by 74 (1)% (0.5 g/l) and 51 (15)% (0.05 g/l). The other IgGs had no inhibitory effects. The IgG from the patient and that obtained commercially did not inhibit the stimulation of cortisol secretion by dibutyryl cyclic adenosine monophosphate or precursors of cortisol. None of the IgGs bound to adrenocorticotrophic hormone. These results suggest that the IgG from the patient acted against the receptor for adrenocorticotrophic hormone, and its presence may explain the patient's raised concentrations of adrenocorticotrophic hormone, failure to respond to exogenous adrenocorticotrophic hormone, and normal basal cortisol concentrations. Addison's disease may thus in some instances be a receptor antibody disease.

Addison Disease↗
PubMed1988

A quantitative cytochemical assay for osteoclast acid phosphatase activity in foetal rat calvaria.

Acid phosphatase activity is prominent in osteoclasts (bone resorbing cells) and has been implicated in the process of bone resorption, although its precise role is not understood. To study the distribution and activity of this enzyme, a quantitative cytochemical method has been developed using undecalcified fresh frozen sections of foetal rat calvariae. Sections were allowed to react with 3 mM naphthol ASBI phosphate at pH 5.0, and the reaction was stopped by rinsing in ice-cold tap water containing 50 mM sodium fluoride. The reaction product was post-coupled to Fast Garnet at 4 degrees C. The absorbance of areas of reaction product in the cytoplasm was measured using scanning and integrating microdensitometry. The initial velocity rate was maintained for up to 2 min at pH 5.0 with a substrate concentration of 3 mM and a section thickness of 5 micron. Under these conditions reaction product was localized to osteoclasts and the surface of bone matrix beneath these cells. Activities in osteoblasts and chondrocytes were negligible. Osteoclastic acid phosphatase was almost totally inhibited by 10 mM fluoride and reduced by 70% by 100 mM tartrate.

Acid Phosphatase↗