Correlation between erythromycin and acid phosphatase in mouse liver.

1. Whole liver homogenates obtained from mice 1h after an intraperitoneal injection of erythromycin lactobionate (343 mg/kg, 1/3 LD 50) were fractionated into nuclear (7000 times g min), mitochondrial (33000 times g min) and lysosomr-rich (250 000 times g min) fractions. 2. The resulting fractions, as well as the final supernatant, were analyzed for erythromycin, acid phosphatase and protein. 3. The highest relative specific activities (per cent total protein) of erythromycin and of acid phosphatase were exhibited by the lysosome-rich fraction. 4. It was of interest, therefore, to examine the effects of erythromycin upon the free activity of acid phosphatase in soluble form and on its in vitro and in vivo release from liver lysosomes. 5. Concentrations of 1.7 - 10-4 M, 3.4 - 10-4 M, 6.8 - 10-4 M and 13. 6 - 10-4 M of erythromycin lactobionate had no significant effect upon the free activity of acid phosphatase in soluble form but retarded the release of this enzyme from the liver lysosome-rich preparation. This effect of erythromycin lactobionate was dose- and time-dependent. 6. Treatment of mice with erythromycin lactobionate (343 mg/kg, 1/3 LD 50) iwtraperitoneally for 7 days significantly decreased the unsedimentable acid phosphatase activity expressed as per cent of total activity in whole liver homogenates. This indicated an in vivo diminished release of acid phosphatase from liver lysosomes by erythromycin. 7. Since erythromycin lactobionate is ionisable it could be possible that erythromycin basis as many other cationic molecules accumulates in lysosomes. 8. The in vitro and in vivo diminished release of acid phosphatase may suggest that erythromycin decreases permeability of lysosomal membrane.

The effects of benzo(a)pyrene on rat liver lysosomes.

An i.p. injection of benzo(a)pyrene (BP; 10 mg/kg) into rats led to the progressive release of hepatic, beta-glucuronidase (beta-Gluc), beta-galactosidase (beta-Gal) and beta-N-acetylglucosaminidase (beta-Glm). This occurred prior to the appearance of altered cells or cell populations from which malignant transformations may gradually develop. The in vitro studies on the latency of beta-Gluc, Beta-Gal and beta-Glm in the lysosome-enriched rat liver suspension treated with BP showed that concentrations of 10(-7) M, 10(-6) M and 10(-5) M significantly decrease latency of all three lysosomal enzymes, the effect being time-dependent. These concentrations of BP did not alter the activities of beta-Gluc, b-Gal and beta-Glm in vitro. No significant alterations were observed in total enzyme activities, following in vivo and in vitro BP administration. BP exerts its effect on rat liver lysosomes by modifying the structural properties of the lysolemma, and may represent an early precarcinogenic change.

The effects of 2,3,7,8-tetrachloro-dibenzo-p-dioxin on human polymorphonuclear leucocytes.

Suspensions of human polymorphonuclear leucocytes were treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) at concentrations 10(-8), 10(-7), 10(-6) and 10(-5) M. The TCDD provoked a progressive extracellular release of the lysosomal enzyme beta-N-acetylglucosaminidase and the cytoplasmic enzyme lactate dehydrogenase in a dose-dependent fashion. At all concentrations TCDD was much more effective in releasing beta-N-acetylglucosaminidase than lactate dehydrogenase. Different responses of the two enzymes to TCDD might be explained by differential structural affinities of beta-N-acetylglucosaminidase for the lysosomal membrane and of lactate dehydrogenase for the cytoplasm. It is likely that TCDD affected the solubility of beta-N-acetylglucosaminidase to a higher extent than that of lactate dehydrogenase, which is probably firmly attached to the cytoplasm.

Effect of sodium thiomalate on immune complex-induced release of lysosomal enzymes from human polymorphonuclear leucocytes.

The extracellular release of beta-glucuronidase and beta-N-acetylglucosaminidase from normal human polymorphonuclear leucocytes initiated with bovine serum albumin/anti-bovine serum albumin immune complex (15 micrograms/ml) was significantly inhibited (p less than 0.01) by pretreatment with increasing concentrations (10(-8) M, 10(-7) M, 10(-6) M and 10(-5) M) of sodium thiomalate in a time- and dose-related fashion. Also, beta-glucuronidase and beta-N-acetylglucosaminidase exhibited similar responses to the effects of bovine serum albumin/anti-bovine serum albumin or sodium thiomalate. In contrast, neither bovine serum albumin/anti-bovine serum albumin nor sodium thiomalate provoked appreciable leakage of the cytoplasmic enzyme, lactate dehydrogenase. This indicates that cell integrity remains intact under the experimental conditions described.

Effects of D-penicillamine, dichlofenac sodium and gold sodium thiomalate upon the selective release of lysosomal enzymes from human polymorphonuclear leucocytes to immune complex.

The selective release of beta-glucuronidase (beta-Gluc) and beta-N-acetylglucosaminidase (beta-Glm) from human polymorphonuclear leucocytes (PMN), initiated with bovine serum albumin/anti-bovine serum albumin (BSA/anti-BSA) immune complex (15 micrograms/ml-1) was significantly reduced by increasing concentrations (10(-7) M, 10(-6) M and 10(-5) M) of D-penicillamine (D-PEN) in a dose-dependent fashion. These effects upon the exocytosis of the lysosomal enzymes studied are in accordance with the results obtained previously in rats with adjuvant arthritis. In contrast, Dichlofenac Sodium (DICHL), which has been found to exert inhibitory activity upon extracellular release of beta-Gluc and beta-Glm in adjuvant arthritic rats in previous studies, had no significant in vitro effect on the exocytosis of these enzymes at the concentrations identical to those of D-PEN. Also, Gold Sodium Thiomalate (GST), in the same concentrations ranging from 10(-7) M-10(-5) M, failed to inhibit selective release of beta-Gluc and beta-Glm in the present investigations. Additionally, BSA/anti-BSA, D-PEN, DICHL and GST did not significantly produce the extracellular release of lactate dehydrogenase (LDH) indicating that under experimental conditions described the cell remained intact. Moreover, neither D-PEN, DICHL, GST or BSA/anti-BSA significantly changed the activities of lysosomal enzyme markers used in these experiments. The possible mechanism(s) of the observed phenomena are discussed.

Comparative studies on the effects of erythromycin A and azithromycin upon extracellular release of lysosomal enzymes in inflammatory processes.

In the present studies the in vivo and in vitro effects of erythromycin A and azithromycin, a new type of macrolide (Fig. 2.), were investigated upon extracellular release of lysosomal enzymes, beta-glucuronidase (beta-Gluc) and beta-N-acetylglucosaminidase (beta-Glm) by using two experimental model systems: in vivo-adjuvant-induced arthritis in rats and in vitro- human polymorphonuclear leucocytes (PMNL) exposed to bovine serum albumin/anti-bovine serum albumin (BSA/anti-BSA), immune complex. Administrations of erythromycin A or azithromycin at doses of 5, 10 and 15 mg/kg into rats one day prior and 2, 4, 6, 8 and 10 days after a single subplantar injection of Freund's complete adjuvant significantly (p less than 0.01) inhibited extracellular release of lysosomal enzymes tested in the synovial fluid of injected left hind paw. These effects were dose-dependent. Further, erythromycin A and azithromycin at concentrations of 10(-7) M, 10(-6) M and 10(-5) M significantly (p less than 0.01) reduced excocytosis of both lysosomal enzymes, beta-Gluc and beta-Glm from human PMNL initiated by BSA/anti-BSA in a dose-related fashion. However, azithromycin was by far more effective (p less than 0.01) in decreasing extracellular release of beta-Gluc and beta-Glm either in the in vivo or in vitro experiments in comparison with erythromycin A. Appropriate control experiments excluded the possibilities that erythromycin A or azithromycin interfered with activities of lysosomal enzymes or with test reagents. Also, in no instances was there enhanced release of a cytoplasmic enzyme LDH.(ABSTRACT TRUNCATED AT 250 WORDS)