In this study, the original method (Lowry method) of Lowry et al. (1951), its modified method (Lowry-TCA method) with protein precipitation by trichloroacetic acid (TCA) and the new method (BCA method) with bicinchoninic acid reaction, were reexamined as to whether these three methods were applicable to urinary protein quantitation of rats. Because of the presence of the urinary interfering substances, the quantitations in the Lowry- and BCA methods were found to be overestimated more than 3 times as large as in the Lowry-TCA method. When the urine sample was diplyzed against water and determined by the Lowry- and BCA methods, more than 24 hours were found to be needed in order to completely exclude the interfering substances from the urine. From these findings, the Lowry-TCA method is recommended for quantitation of urinary protein in rats.
Cardiac effects of ketanserin were examined mainly electrophysiologically with using rat and guinea pig heart muscle preparations. 10<-6>M ketanserin slightly antagonized the positive chronotropic but not inotropic action of serotonin in spontaneously beating guinea pig atria. Ketanserin, only at the concentration as high as 10<-4>M, produced sIight rightward shift of the positive chronotropic but not inotropic dose-response curves for norepinephrine in guinea pig atria. In both rat and quinea pig atria, ketanserin per se produced negative chronotropic effect and slight prolongation of action potential duration (APD) at high concentrations, 0.1 or 0.3mg/ml. In guinea pig ventricular preparation, 1mg/ml of ketanserin did not affect the rate of rise of the action potential (+Vmax), action potential amplitude and APD. In rat ventritular free wall preparations, 1mg/ml of katanserin produced slight increase in APD without affecting the other action potential parameters. In rat ventricular papillary muscle and septum preparations, 0.3 mg/ml of katanserin tended to produce a decrease in +Vmax and an increase in APD. However, since these changes were produced only at extremely high concentrations and slight in degree, it was concluded that ketanserin does not produce electrophysiological side effects of clinical relevance.
Intravenous (iv) administration of tri-o-cresyl phosphate (TOCP) caused a delayed neurotoxic effect in hens similar to that produced by oral and dermal administration. The iv ED50s for producing ataxia and paralysis were estimated to be 15.9 mg/kg and 31.7 mg/kg respectively. The tissue disposition of unaltered TOCP was determined in hens following a single iv injection of 40 mg/kg of TOCP. One hour (hr) after the injection, the leg muscle contained the highest concentration, 26.99 μg/g fresh weight followed by the adipose tissue. Among the nerve tissues, the sciatic nerve had the highest concentration, 9.63 μg/g followed by the spinal cord and the brain. Except the adipose tissue and the sciatic nerve, the concentration in all analyzed tissues dropped below 1.0 μg/g (ml) after 24 hr. An unidentified metabolite appeared in bile taken 1 and 3 hr after the injection. Pretreatment of hens with 3-methylcolathrene (3-MC) and β-naphthoflavone (B-NF) protected against the TOCP-induced delayed neuro-toxicity, whereas phenobarbital (PB) failed to protect against the neurotoxicity. Plasma creatine phosphokinase (CK) activity in paralytic birds increased approximately 4 times of the control or symptomless hens on the 21st day. 3-MC-, B-NF- and PB-treatment depressed substantially the concentration of unaltered TOCP in brain and plasma 1 hr after iv dosing with 40 mg/kg of TOCP. Only B-NF pretreatment lowered the level of TOCP in spinal cord. There was no effect of these inducers on the level of TOCP in sciatic nerve and adipose tissue. B-NF and 3-MC lowered significantly the TOCP level in leg muscle, whereas PB had no such effect. More attention should be paid to the role of TOCP in muscle, especially to the leg muscle, judging from the present toxicological and metabolic studies.
Conversion of absorbance unit into molar amount was tried as to deoxydinucleotide. In order to achieve this trial, a reversed-phase high-performance liquid chromatographic method with a linear gradient mode was established for separation and quantification of deoxymononucleotides and deoxynucleosides. Selecting 2'-deoxycytidylyl-(3'-5')-thymidylic (5') acid as an example of deoxydinucleotides, this compound dissolved in water was estimated in absorbance unit at 260nm, and it was treated by alkaline phosphatase and furthermore by snake venom phospho-diesterase. Based on quantification of the cleaved nucleic acid constituents including 2'-deoxycytidine 5'-monophosphoric acid and thymidine by the above method, the molar amount per 1.000 absorbance unit at 260 nm in the deoxydinucleotide was determined. Thus, the conversion of absorbance unit into molar amount is considered to be applicable to other deoxy-oligonucleotides.
Incubation of isolated rat hepatocytes with high concentration of β-lactam antibiotics, cephaloridine (CER), flomoxef (FMOX) or cephamandole (CMD), resulted in significant reduction of cellular glutathione (GSH) levels, though cell viability was not affected during the incubation period. I.v. injection of a large dose, 300 mg/kg, of these β-lactam antibiotics to rats did not affect the hepatic GSH levels. The concentration of β-lactam antibiotics in the body fluid of the rats were found to be much lower than the amounts which causes GSH depletion in vitro.
The effects of rokitamycin (RKM), a macrolide antibiotic, on young rats with hyperbilirubinemia were investigated. RKM at a dose of 1, 000 mg/kg was orally administered to 14-day-old rats with hereditary, non-hemolytic hyperbilirubinemia (homozygous Gunn rats, total plasma bilirubin concentration : about 7 mg/dl). Animals given 10 ml/kg of 0.5% carboxymethyl cellulose (CMC) were used as control. Plasma total bilirubin concentration, plasma unbound bilirubin concentration and derebellar bilirubin level did not significantly change during 1, 3, 6 and 24 hours after administration of RKM or CMC. There was no significant difference in plasma total bilirubin concentration, plasma unbound bilirubin concentration and cerebllar bilirubin level between RKM-treated and control animals at 1, 3, 6 and 24 hours after the administration. No localized yellow discoloration of the brain tissue (non-cerebellar parts) was noted at 1, 3, 6 and 24 hours after administration of either RKM or CMC.