Intrarenal distribution of cytochrome P-450 (P-450) was investigated with different segments of isolated single nephrons from rabbits and rats by using a new ultra-micro method of P-450 determination. In both animals, P-450 was localized only in the proximal tubule. Other segments such as the glomerulus, the loop of Henle, the distal tubule, and the collecting tubule possessed no P-450 at all. Within the proximal tubule, the straight portion (S2 and/or S3 segments) revealed a higher specific content of P-450 than the convoluted one. An inducer of P-450, 3, 4-benzo(a)pyrene increased the P-450 of a definite portion (second 3mm from the glomerulus) almost doubly in rabbits. In rats, both 3-methylcholanthrene (3MC) and 48 hr starvation (Fast) induced P-450, but only the later increased laurate-ω-hydroxylation. P-450 in the proximal convoluted and straight tubules was induced separately by Fast and 3MC, respectively. These results indicate that renal mixed function oxidase should be confined to the proximal tubule and that, like the liver, multiple forms of renal P-450 should exist in the different proximal segments.
Metabolism of platelet-activating factor (PAF) in rabbit plasma or in rabbit platelets was studied. 1. [C3H3]-Labeled PAF was degraded into IysoPAF and choline in plasma. An agonist of PAF, NT071 was not degraded in the plasma. Albumin protects the degradation of PAF in plasma deprived of albumin but not the degradation of lysoPAF. These findings indicate that PAF may be metabolized in plasma by acetylhydrolase and then by lysophospholipase D. 2. PAF was converted to phosphatidylcholine (PC) in washed rabbit platelets. The radioactivities in PC was recovered in the fraction of lysoPC after mild alkaline treatment, suggesting that the product is 1-alkyl-2-acyl-glycerophosp ho choline. 3. The binding of PAF and lysoPAF to rabbit platelets, rabbit erythrocytes and liposomal membranes were next examined. The binding of PAF to various membrane; was inhibited by albumin. Albumin also suppressed the activation of platelets by PAF. A monomeric form of PAF, which is free from albumin, may react with target cell membrane and also to be degraded by catabolic enzymes. 4. The binding of lysoPAF to platelets, erythrocytes and liposomes was more effectively inhibited by albumin than that of PAF. The affinity of PAF to lipid bilayers may be higher than that of lysoPAF.
The dependence of the phagocytosis of particulate materials on their size was studied. Rabbit alveolar macrophages (AMs) obtained by lung lavage were cultured in suspensions or monolayers with Latex particles of 1 μm or 2 μm in diameter. After culturing AMs with 107-5×109 Latex particles per ml for 15 to 360 minutes, the number of phagocytized particles in each of 100 individual cells was counted by light microscopy. In suspension culture, there was no significant difference in the average number of particles phagocytized per AM between 1 μm and 2 μm particles in the identical conditions as to the particle concentration (particle number/ml) and the incubation time. In monolayer culture, it was difficult to compare the average number of 1μm particles phagocytized by AM with that of 2 μm ones in the identical condition as to the particle concentration, since the sedimentation velocities at which particles sank to the bottom of culture chamber were different between both particles, resulting in the difference of particle concentration around AMs. The sign of saturation was observed when the average number of phagocytized particles reached approximately 10 particles per AM in either case of suspension culture with 1 μm or 2 μm particles and approximately 45 of 1 μm and 10 of 2 μm particles in monolayer culture.
This report dealt with the effects of dimercaprol (BAL) and thiotic acid (TA), antidotes against arsenical, on the distribution and the excretion of <74>As in several organs of the rat. Each organ was removed and served for quantitative analysis of <74>As five days after subcutaneous injection of Na3<74>AsO35 μCi/100 g. Administration of BAL or TA was performed intraperitoneally with a single administration or five consecutive administrations for five days before animals were sacrificed. <74>As content in each organ of the rat decreased to a greater extent in the five consecutive administration group of BAL or TA than in the non-treated or single administration groups. Moreover, the excretion of <74>As in a digestive tract increased more remarkably in the five consecutive administration group than in the non-treated or single administration groups. There were no differences in the excretion or the content of <74>As in each organ between the single administration group and the non-treated group.
Most environmental pollutants affect biological membranes more or less, resulting in an increase in permeability of mitochondrial and red cell membranes, which causes changes in potassium compartmentation, and also impairment of oxidative phosphorylation of mitochondria. Authors classified various environmental pollutants from the mode of action on biological membranes.
The urine of the mice fed on a 15% sorbic acid diet was treated with or without β-glucuronidase and was fractionated by XAD-2 column chromatography. The non-polar urine fraction was slightly mutagenic towards TA 98 when metabolically activated, but not towards TA 100. From the comparison of thin-layer chromatograms between the intestinal and urinary samples, it was suggested that a part of the mutagens produced in the intestine was excreted in the urine. As for the lipid peroxidation, the levels of lipid peroxide in the liver of the mice fed on a 15% sorbic acid diet were lower than those in the control over the feeding period of 15 months. Moreover, there was a correlation between the concentration of sorbic acid (X) in the diet and the lipid peroxide level (Y) in mice fed on potassium sorbate diets, obeying the linear equation, Y=-8.39X+341 (p<0.01). However, the lipid peroxide levels of 15% sorbic acid group did not fit with the above equation, and was higher than those of 20.1% potassium sorbate group, which was equivalent to 15% sorbic acid group in respect of sorbic acid concentration. Accordingly, the difference of lipid peroxide levels between the two groups (15% sorbic acid and 20.1% potassium sorbate group) might reflect productive difference of the mutagens.
Acute toxicity of Ketoprofen, a nonsteroidal anti-inflammatory analgestic, was studied using rat weanlings. Ketoprofen was intrarectally administered in the form of a mixture with T10, a basic materials for suppositaries. The results obtained were as follows : 1. LD<50> of KP was estimated to be 434 mg/kg in male weanlings and 496 mg/kg in female weanlings. These values were about four times higher than those obtained from our previous study (Shimpo et al., 1981) using six-weeks old abult rats of both sexes. The fact indicated that rat weanlings were far tolerant to KP intrarectally administered than young adult rats. 2. Intrarectal administration of KP at high doses, caused death between the second and the seventh day after administration. Gross and histopathological examinations revealed that dead weanlings carried perforative peritonitis with ulcers mainly in jejunum and ileum not in rectum. It was therefore suggested that the ulcer was produced in small intestine by entero-hepatic circulation of KP and finally mortal peritonitis occurred.
Studies on antigenicity of suloctidil were performed on ASA, Schultz-Dale reaction, PCA and PHA in guinea pigs. Two sensitizing procedures were enforced. One was performed by means of treatment of suloctidil (p.o. and i.p.) and the other was done by means of injection of suloctidil, suloctidil-BSA-mixture and suloctidil-BSA-conjugate emulsified with FCA. Guinea pigs treated with suloctidil by oral or intraperitoneal administration showed no ASA, Schultz-Dale reaction, PCA and PHA by the challenge of suloctidil. The animals treated with suloctidil-BSA-conjugate only evoked severe anaphylactic reaction to challenge of suloctidil-OVA-conjugate. Guinea pigs treated with suloctidil and suloctidil-BSA-mixture showed no anaphylactic reaction to challenge of suloctidil, suloctidil-OVA-mixture and suloctidil-OVA-conjugate. The animals sensitized with suloctidil-BSA-conjugate showed no anaphylactic reaction to challenge of suloctidil and suloctidil-OVA-mixture. Therefore, it is concluded that suloctidil does not have any antigenicity.