Polyamines tissue concentrations

Specific uptake systems may account for selective localization in tissues, and this may be the explanation for toxic effects in those particular tissues. For example, the herbicide paraquat (Fig. 3.16) is taken up by the polyamine transport system into the lungs and thereby reaches a toxic concentration (see chap. 7 for a detailed description of this system). 

The high concentration of OCT is in hepatic tissue relative to other tissues this leads to this enzyme being regarded as a liver-specific enzyme. OCT is localized in the periportal mitochondria and is the second of the five enzymes in the urea cycle. The enzyme measurement should not be confused with ornithine decarboxylase (ODC), which is of interest in studies of polyamine metabolism. The use of the method has been limited by some of technical requirements for the older assays, but newer enzymatic methods may increase its use (Peltenburg et al. 1991 Isobe, Matsuzawa, and Nagamura 1993 Ishikawa et al. 2002). In a number of rat studies, ALT was found to be more predictive of hepatotoxicity than OCT (Bondy et al. 2000). 

High concentrations of polyamines occur in fetal and neoplastic tissues and in seminal fluid. These tissues represent antigenic challenges that often do not elicit appropriate immune response of the host organism (for reviews see Selmeci et al., 1985 Normann, 1985 Morgan, 1987 Bulmer,... 

Polyamines are formed from ornithine and SAM, thus aflEording an alternative fate for this purine derivative (P3). The polyamines, as well as adenosine, regulate transmethylation (Hll, L3). Ornithine decarboxylase is produced in greater quantity in rapidly dividing cells (B17, D7, Rl, RIO). Levels of S-adenyosylmethionine decarboxylase are also increased in such tissues (H2, R9). There is evidence that this increase is cyclic AMP mediated (B7), This ties these compounds although indirectly to adenosine concentrations. 

Samples were deproteinized with 0.2 M HC104- Before reaction with 0PA-thiol, a known amount of 3-3 -diaminodipropylamine was added to the tissue homogenates as an internal standard and perchloric acid extracts were adjusted to pH 9.5 by addition of borate buffer. For quantitation, polyamines were compared to the internal standard. The peak height ratios of polyamine to internal standard for a known concentration of polyamine was presented in Table 1. 

Diamine Oxidase Diamine oxidase (DAO, his-taminase) is a degradative enzyme of the polyamine metabolic pathway that is expressed in mature epithelium lining the rodent intestinal villi (Luk et al., 1980). Diminished blood concentrations, measurable by tritiated water assay, have been shown to correlate well with tissue expression... 

Two Cig columns and a guard column were used for separation. The mobile phase was methanol/water (65 35 v/v). The benzoylated putrescine, 1,6-hexanediamine, spermidine and spermine were separated in 10 min. Detection was at the absorption maximum of 229 nm (instead of 254 nm) with a detection limit of 1 pmol. The linear range was up to 100 nmol of polyamine and the recoveries for putrescine, spermidine and spermine were 104.7 + 3.4%, 97.3 + 3.7% and 88.8 5.5% respectively. Considerably lower spermidine and putrescine concentrations were found in tumour tissues obtained from animals treated with DL-a-difluoromethylomithine for seven days compared with untreated controls. 

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