Yasuo Kakiuchi

Distribution and binding pattern of benzo(a)pyrene in rat liver, lung and kidney constituents after oral administration

Orally administered 3H‐benzo(a)pyrene (BP) was persistent in protein fraction of liver, lung and kidney. The radioactivity in this fraction increased with time after administration and accounted for about 50%, 40% and 65% of total radioactivity in liver, lung and kidney, respectively at 48 hr. The BP metabolites binding proteins were located in cytosol and had molecular weights of 40,000–60,000 and 80,000–100,000 as determined by gel filtration and polyacrylamide gel disc electrophoresis. In addition, at 48hr after administration, about 80% of radioactivity in high molecular weight protein fraction was found to be precipitated by trichloroacetic acid treatment. These results suggest that BP metabolites might be transported by and are persistent in these protein fractions of liver, lung and kidney if the intake of BP is continuous. These proteins, therefore, appeared to be closely related to cell toxicity or mutagenicity in these organs as well as DNA.

Metabolism of benzo(a)pyrene in rat by oral administration

Abstract Orally administered 3 H-benzo(a)pyrene (BP) was concentrated in liver, kidney and lung of rat. Liver contained BP-diols, BP-quinones and 3-hydroxy-BP, and extremely high amounts of BP-quinones and unmetabolized BP were found in lung until after 7 hr of administration. In kidney, BP-quinones and BP-diols were major metabolites, but not BP or 3-hydroxy-BP. Low level of metabolites as conjugates with glucuronate and more polar compounds were also detected in kidney. These results suggested that an orally administered BP was metabolized to BP-diols and 3-hydroxy-BP mainly in liver, to BP-quinones mainly in lung, and to BP-diols and glucuronides or more polar compounds mainly in kidney.

Polycyclic aromatic hydrocarbons affect the calcium ionophore induced activation of rabbit platelet

Abstract The effect of 11 polycyclic aromatic hydrocarbons (PAHs) on calcium ionophore A-23187 induced activation of washed rabbit platelets has been examined. Platelet activation was measured by thromboxane B 2 (TXB 2 ) synthesis using enzyme immunoassay (EIA) for determination. The results reveal that anthracene and pyrene were synergistic, while benz(a)anthracene, chrysene, benzo(a)pyrene and benzo(ghi)perylene had inhibitory effects. These effects were abolished by removal of PAHs before A-23187 stimulation. The amount of TXB 2 and the concentration of intracellular calcium ion related closely. The little or/and no protein kinase C connection to synergism of these PAHs also demonstrated.

Changes in the composition of glutathione transferase subunits in rat liver after oral administration of Benzo[a]Pyrene

The oral administration of 50mg/kg of B[a]P for 10 days resulted in an increase in the activity of glutathione (GSH) transferases of the liver cytosol, but not of the microsomal fraction. The cytosolic enzyme activities toward l‐chloro‐2,4‐dinitrobenzene and l,2‐epoxy‐3‐(p‐nitrophenoxy)propane was increased by 1.9‐fold and 1.6‐fold, respectively, while a little or no change was observed in the activities toward 1,2‐dichloro‐4‐nitrobenzene and ethacrynic acid. When GSH transferase subunits were determined using a reverse‐phase HPLC technique coupled with the S‐hexyl affinity chromatography, the subunit 1 was preferentially induced by the B[a]P treatment as compared with other subunits, consisting with the substrate spectrum of the GSH transferases. On the other hand, phenobarbital (80 mg/kg, i.p. for 4 days) induced the subunit 1 followed by subunits 3 and 2, but not subunit 4. Thus the induction pattern of the subunits in the rat treated with B[a]P was quite different from that with phenobarbital. These d...

Rubber additives inhibit the calcium ionophore and thrombin induced activation of rabbit platelets

Abstract Together with the mutagenic activities of 5 rubber vulcanization activators (tetramethylthiuram disulfide[TMTD], zinc dimethyldithiocarbamate[ZDMC], zinc diethyldithiocarbamate[ZDEC], sodium dimethyldithiocarbamate[SDMC] and sodium diethyldithiocarbamate[SDEC]), the effect of these compounds on thrombin or calcium ionophore A-23187 induced activation of washed rabbit platelets has been examined. The mutagenicity was investigated in Ames test, and platelet activation was measured by thromboxane B 2 (TXB 2 ) synthesis and the amount of TXB 2 was determined by enzyme immunoassay (EIA). In mutagenic assay, TMTD, ZDMC and SDMC were mutagenic, on the other hand, all tested compounds inhibited the platelet activation induced by thrombin or A-23187 when they were added simultaneously. The thrombin induced platelet activation was inhibited in proportion to the increased concentration of rubber vulcanization activators. There was not so much IC 50 differences (2–4×10 −8 M) between these compounds against the platelet activation by thrombin. For A-23187 induced platelet activation, the extent of inhibition by these compounds occurred independently of the concentrations used. When platelets were pretreated with these compounds for 5 min before stimulation with thrombin or A-23187, the decreased synthesis of TXB 2 was observed with all compounds. These inhibitory effects were not abolished after removal of the compounds. No correlations were observed between mutagenic activity and inhibitory effect of these rubber vulcanization activators.

Food additives on acceptable daily intake (ADI) level affect the agonist induced platelet activation I. Antioxidants and preservatives

The effect of food additives on cellular functions was examined. Rabbit washed platelets were treated with five antioxidants [butylated hydroxytoluene(BHT), butylated hydroxyanisole(BHA), propyl gallate(PG), ascorbyl palmitate(AP), dl- α -tocopherol(VE)] and three preservatives [thiabendazole(TBZ), diphenyl(DP), o-hydroxydiphenyl(OPP)], and the amount of thromboxane B2(TXB2) synthesized was determined as an indicator of platelet activation. Calcium ionophore A-23187 induced TXB2 synthesis was inhibited by the presence of BHA or PG at 10−6M, BHT or AP at 10−5M. In contrast, thrombin induced TXB2 synthesis was inhibited more significantly than A-23187 induced ones at 10−8M of BHT, PG, AP or VE, 10−7M of BHT. The inhibitory effects of these food additives on A-23187 induced TXB2 synthesis recovered the removal of these compounds, but no recovery was observed in thrombin induced ones. Collagen induced TXB2 synthesis was inhibited by 10−6M levels of BHA or PG, and 10−5M of DP or OPP. AP seemed to have biphasic effects depended on its concentration, and others had no effect on collagen induced TXB2 synthesis.

Metabolism of 3-hydroxybenzo (a) pyrene in rat, isolated hepatocytes and kidney

Abstract After intravenous injection of 3-hydroxybenzo (a) pyrene into rat, benzo (a) pyrene-diols were detected in urine, and in vitro experiment using isolated hepatocytes and sliced kidney also indicated the metabolism of 3-hydroxybenzo (a) pyrene to diol derivatives. THese results suggested the presence of unknown metabolic pathway of benzo (a) pyrene-phenols such as 3-hydroxybenzo (a) pyrene to diol derivatives both in vivo and in vitro .

Effect of halocarbons and styrene on thrombin and calcium ionophore induced activation of rabbit platelets

Abstract The series of study about the effect of environmental pollutants on cell functions, the influence of several volatile halocarbons (trichloroethylene, tetrachloroethylene, trichloroethanol, bromodichlomethane, chlorodibromomethane and bromoform) and styrene on calcium ionophore (A-23187) or thrombin induced activation of washed rabbit platelets has been examined. Platelet activation was measured by thromboxane B 2 synthesis. As a result, tetrachloroethylene and trichloethanol inhibited both A-23187 and thrombin induced platelet activation significantly. Bromoform had an inhibitory action at its highest concentration(10uM) against A-23187 induced platelet activation. Styrene and bromoform revealed a strong inhibitory action against thrombin induced platelet activation. There seemed to be no concentration dependent inhibition of these compounds against platelet activation induced by both agonists. When platelet was pretreated with these compounds, all compounds except trichloroethylene inhibited thrombin induced platelet activation. These result suggest the importance of monitoring the environmental concentration and distribution of widely used volatile compounds which may be potentially hazardous to our health.