Intracellular glutathione (GSH) content was measured by flow cytometry using monochlorobimane (mBCl) and by the enzymatic assay in a set of 6 sublines of murine L1210 leukemia cells made resistant to ...DNA-interacting agents having distinct mechanisms of action: L-phenylalanine mustard (L-PAM), 1,3-bis(2-chloroethyl)-I-nitrosourea (BCNU), cisplatin (DDP), N-deformyl-N-(4-N,N-bis(2-chloroethylamino) benzoyl) distamycin A (FCE 24517), doxorubicin (DX) and 3'-deamino-3' (2-methoxy-4-morpholinyl)-doxorubicin (FCE 23762). A significant correlation was demonstrated between the mean intracellular mBCl fluorescence values measured by flow cytometry and levels of GSH measured by the classical enzymatic assay, despite the possible influence of glutathione-S-transferases and of other thiols on the mBCl fluorescence. Although less specific, the flow cytometric method is more informative than the enzymatic assay, allowing detection of fluorescence distributions, which we proved to be characteristic of each subline. In order to assess a procedure enabling a quantitative analysis to be made of intercellular GSH heterogeneity, we propose the use of appropriate thresholds and parameters of the mBCl flow cytometric distribution. By use of this analysis procedure, distinct types of alterations, with respect to the heterogeneity distribution of the parental L1210 cell line, have been evidenced in resistant cells. A uniform increase in mBCl fluorescence was observed among cells of the sublines resistant to L-PAM and FCE-24517. The mean mBCl fluorescence increase in sublines resistant to DX and DDP was due to a higher number of cells with fairly high mBCl fluorescence, but still within the range spanned by the parental cell line. A less heterogeneous mBCl fluorescence distribution was found in the L1210 subline resistant to FCE 23762, which was, however, similar to a cloned sensitive line. Though GSH was linked to the principal cause of drug resistance only in the L-PAM-resistant cell line, alterations in heterogeneity, as detected by mBCl fluorescence distributions, were found in 5 out of 6 resistant lines.
1
Hypolipidaemic agents may increase biliary cholesterol in man, inducing a supersaturated bile.
2
To evaluate this possible side‐effect, we have studied bile lipid secretion over a period of 8 h ...with intact enterohepatic circulation and 4 h with complete interruption in rats treated for two months with a salt of cholestyramine and 2‐4‐(p‐chlorobenzoyl)‐phenoxy2‐methyl propionic acid (α‐1081, 1.150 g/kg body wt., daily), cholestyramine (1.125 g/kgbody wt. daily), procetofenic acid (25 mg/kg body wt. daily) and saline respectively (six rats for each group).
3
Cholesterol saturation index significantly (P< 0.005) increased (from 0.21 ±0.01 to 0.39±0.09, mean±s.d.), in rats fed with procetofenic acid but it did not in α‐1081‐ and cholestyramine‐treated animals.
4
Procetofenic acid and, to a lesser extent, cholestyramine increased the bile flow. Procetofenic acid increased cholesterol secretion from 0.45±0.17 to 0.94 ± 0.19 μmol kg−1 body wt. h−1 (mean±s.d.).
5
Cholestyramine increased both serum cholesterol and bile acid secretion from 0.45±0.17 to 0.68±0.10 and 25.8±9.48 to 39.96 ± 6.68 μol kg−1 body wt. h−1 respectively; α‐1081, on the contrary, had no effect on bile lipid secretion.
6
These data suggest that α‐1081 may be used as a new hypolipidaemic drug without any risk of increasing cholesterol in bile.
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