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Heavy metals accumulation in parallel with the evaluation of physiological and biochemical effects resulting from continued metal exposure were considered here using for the first time the great white-toothed shrew Crocidura russula as an in vivo model. Shrews were originated from an abandoned lead/zinc mining area and from a reference area, both in Alentejo, southern Portugal. Hepatic contents of nickel, copper, zinc, cadmium, mercury and lead were quantified by Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Haematological parameters (white blood cells, red blood cells, haemoglobin and haematocrit) were obtained in a Coulter Counter Analyser and biochemical markers of the redox balance (glutathione S-transferase, glutathione peroxidase, and glutathione reductase) activities were measured spectrophotometrically using a Duo-50 spectrophotometer. Compared with control animals, significantly higher concentration of hepatic cadmium (9.29 vs. 1.18 micorg/g dry weight) and nickel (1.56 vs. 0.343 microg/g dry weight) were detected in the shrews collected in the mining area. However, no significant changes were observed on haematological or enzymatic parameters in animals exposed to metal pollution. The obtained results show that shrews are good bioaccumulators of toxic heavy metals, but very tolerant to their effects, revealing an interesting long-term adaptation to polluted environments. In addition, this study provides reference values for haematological parameters and antioxidant enzymes levels in C. russula, which may be relevant for comparative purposes in further studies.

To assess the risk from heavy metal accumulation to insectivorous species exposed to different pollutants, shrews [Sorex araneus (Linnaeus 1758) and Sorex minutus (Linnaeus 1766)] were collected in the Olkuski Ore Region (OOR; a Zn and Cd smelter area), Legnicko-Głogowski Copper Mine Region (LGCR; a copper ore-mining area), and Białowieza Forest (BF; a control area). A few sites were chosen in each region and a total of 57 animals were collected from them. The liver and kidneys were dissected from the animals, dried, and digested in a 4:1 mixture of HNO3 (nitric acid) and HClO4 (perchloric acid). Cadmium, lead, zinc, copper, and iron were determined in the samples by flame or flameless atomic absorption spectrometry. The interactions between toxic and essential metals were calculated for each tissue. The data showed that accumulation of metals by insectivores is high; shrews accumulated much higher amounts of cadmium and lead than bank voles, studied by other researchers, from the same areas. The expected high tissue accumulation of copper at LGCR and zinc at OOR was not seen, but the levels of both elements were higher in the tissues of shrews from OOR than from LGCR. The lowest copper concentrations were in the tissues of shrews from BF. The highest cadmium and lead concentrations were found in the tissues of shrews from OOR. Some significant correlations were found between the tissue concentrations of xenobiotic and essential metals (e.g., between cadmium and zinc and between lead and iron).

We measured the enzymes of glycolysis, Krebs Cycle, beta-oxidation and electron transport in the heart, liver and skeletal muscle of the Northern Short-tailed Shrew, Blarina brevicauda. Additionally, we measured the amount of myoglobin in skeletal and heart muscle as well as the concentration of glutathione in heart. The picture that emerges is of an aerobically well-endowed animal with constrained anaerobic capacity as indicated by small activities of glycolytic enzymes and creatine kinase. Lipid metabolism and amino acid transamination, as well as gluconeogenesis, are predominant in processing carbon resources and probably reflect the large contribution lipid and protein make to the diet of this carnivore. The citrate synthase activity is the largest of any reported value for vertebrate heart (250 U/g). The additional, very active cytochrome c oxidase activity (220 U/g) and large myoglobin concentrations (8 mg/g) in heart are clearly the underpinnings of the rapid metabolic rates reported for small insectivores. The potential for generation of reactive oxygen species must be great since the total glutathione concentration (165 mumol/g) is 300-fold greater in shrew hearts than in hearts of rats.

Suncus murinus (suncus) is an animal species highly sensitive to ethanol (Lin, S.-C., Saito, H., Yohro, T. and Shiga, J.,J. Toxicol. Env. Health, 18: 575-587, 1986). To elucidate the mechanism involved in sensitivity to alcohol, we investigated that properties of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in the suncus in comparison with the rat. The activities of ALDH in microsomes and mitochondria of suncus livers were lower than those in rat livers, although the activity of cytosolic ADH was not different between the suncus and the rat. We propose that the high sensitivity of the suncus to alcohol can be accounted for, at least in part, by the low activity of ALDH in suncus liver.

The amounts of several drug-metabolizing enzymes in livers of Suncus murinus (suncus) were studied in comparison with rats. The content of cytochrome P450 in suncus was less than one third that seen in rats. Activities of glutathione S-transferase, UDP-glucuronyltransferase and arylhydroxycarbon hydroxylase in suncus were less than half those in rats. Activity of flavin-containing monooxygenase in suncus was 71% that of rats. Interestingly, N-acetyltransferase (NAT) activity in suncus liver cytosols was not detectable: no detectable activities were seen with aniline, p-aminobenzoic acid and p-amino-salicylic acid as substrates. We propose that suncus is a unique animal possibly lacking NAT in liver cytosol.

The distributions of trace metals in tissues of shrews in a series of feeding trials are described. The relationship between body cadmium burden and organ weight was directly related to differences in body weight. Organ weight expressed as a percentage of body weight was constant in the kidney, but was correlated with cadmium burden for the liver. Liver and kidney accounted for up to 80% of total body cadmium. The proportion of the body cadmium burden found in the kidney ranged from 8 to 17%. Copper and zinc concentrations in the kidney increased in response to cadmium accumulation. Hepatic zinc concentrations increased with cadmium accumulation. Exposure to a copper-contaminated diet resulted in increased liver copper levels. High liver concentrations were correlated with high kidney concentrations. At the lowest levels of exposure to metals liver and kidney concentrations were similar, but as exposure increased so did liver concentrations and much more so than in the kidney.

The structure of the liver of the thick-tailed shrew (Suncus murinus) was studied with special reference to the vitamin A-storing cell. The macroscopic arrangement of hepatic lobes was the same as those of rodents. Connective tissues of Glisson's sheath were not prominent. There were gradual differences in the size and the cytoplasmic contents of hepatocytes among perihepatic, intermediate, and periportal regions. These correspond to the acinar zones 3, 2, and 1 of Rappaport, respectively. The ultrastructural features of the hepatocyte were numerous microvilli, a large mass of glycogen particles (alpha-particles), and well-developed Golgi complexes and lysosomes in the peribiliary region. Cellular elements of the sinusoid were the same as those of rodents. Vitamin A-storing cells were demonstrated by autoradiography of tritiated retinyl acetate administered orally. They were distributed in the perihepatic and intermediate regions. The number of vitamin A-storing cells was much smaller than that in the mouse liver and did not increase after excess vitamin A was given to the animal. Cytological features of the vitamin A-storing cells in Suncus liver were similar to those for other mammalian livers. The scarceness of vitamin A-storing cells and the low amount of vitamin A esters suggest that Suncus does not store much vitamin A in the liver.

Characteristics of mixed-function oxidases in the liver of house musk shrew, Suncus murinus, were studied. The basal level of cytochrome P-450 and the activity of drug-metabolizing enzyme in hepatic microsomes of Suncus murinus is relatively lower than that of rats, while the level of cytochrome b5 and NADPH-cytochrome c reductase is approximately the same as that of rats. The treatment of Suncus murinus with phenobarbital and 3-methylcholanthrene elevated the level of cytochrome P-450 and the activity of drug-metabolizing enzymes, but not the level of cytochrome b5. Two distinct forms of cytochrome P-450 have been purified from hepatic microsomes of 3-methylcholanthrene-treated Suncus murinus. These forms have their absorption maximum at 448.0 nm and 448.5 nm in CO-bound reduced form, and one is in the high-spin state and the other is in the low-spin state. They are different in their molecular weights (53,500 and 55,000) and in their spectral and catalytic properties. Characteristics of these forms were compared with those of the major forms of cytochrome P-450 purified from livers of rats treated with 3-methylcholanthrene.

Serum constituents and liver of the wild male suncus as well as of those bred and fed in our laboratory were examined serologically and histologically. The following results were obtained: The serum glutamic-oxaloacetic transaminase, gamma-glutamyl transaminase, inorganic phosphate, blood urea nitrogen, creatinine, uric acid, and zinc turbidity test levels of wild suncus were higher than those of 4 and 8 week old fed suncus. The total cholesterol level of wild suncus was lower than those of 4 and 8 week old fed suncus. In wild suncus, the total bilirubin and direct bilirubin levels were higher, and the Ca and albumin levels were lower than those of 4 week old fed suncus. However, no significant differences were observed between the wild and the 8 week old fed suncus. Although the alkaline phosphatese and thymol turbidity test levels of wild suncus were larger than those of 8 week old fed suncus, no significant differences were observed between the wild and the 4 week old fed suncus. The histological study revealed the presence of fatty droplets in only 2 of the 67 wild suncus examined while fatty droplets (grade +) were observed in almost all the fed suncus. In one case of the wild suncus, moderate round cell infiltration in interlobular connective tissue was found.

1. Starch gel electrophoresis of adult shrew (Suncus murinus) liver extracts revealed five forms of alcohol dehydrogenase (ADH 1-5) and four of them were purified. 2. ADH-4 and ADH-5 resemble human class I ADH in terms of electrophoretic mobility, substrate specificity and sensitivity to pyrazole inhibition. 3. ADH-2 does not belong to any of the three classes of human ADHs but rather with catalytic properties similar to those of the class B ADH found in guinea pig liver. 4. ADH-1 prefers secondary alcohol over primary alcohol substrates and between the enantiomers tested, the enzyme favors the S isomers.