Comp. Biochem. Physiol. Vol.99B, No. 3, pp. 673--677,1991 03054)491/91 $3.00 + 0.00 Printed in Great Britain © 1991Pergamon Press pie COMPARATIVE STUDIES ON THE DISTRIBUTION OF RHODANESE IN DIFFERENT TISSUES OF DOMESTIC ANIMALS MAHMOUDAMINLARI*~and HASSAN GILANPOURi" *Department of Biochemistry and i'Department of Anatomy, School of Veterinary Medicine, Shiraz University, Shiraz 71365, Iran (Received 18 December 1990) Almtraet--l. The activity of rhodanese in different tissues of some domestic animals was measured. 2. Rhodanese was present in all tissues studied. 3. The activity of rhodanese in most tissues of sheep was higher than other animals studied. 4. In sheep and cattle the epithelium of rumen, omasum and reticulum were the richest sources of rhodanese. Significant activity of rhodanese was also present in liver and kidney. 5. In camel the liver contained the highest level of rhodanese followed by lung and rumen epithelium. Camel liver contained a third of the activity of sheep liver. 6. Equine liver had a third of the activity of sheep liver. Other tissues showed low levels of rhodanese activity. 7. Dog liver contained only 4% of the activity of sheep liver. In this animal, brain was the richest source of rhodanese. 8. The results are discussed in terms of efficacy of different tissues of animals in cyanide detoxification. INTRODUCTION The enzyme rhodanese (E.C. 2.8.1.1.; thiosulfate: cyanide sulfurtransferase) is a ubiquitous enzyme and its activity is present in all living organisms from bacteria to man (Westely, 1974; Chew and Boey, 1972; Ryan et al., 1978; Dudeck et al., 1980; Janse van Resenberg and Shabort, 1984; Beesley et al., 1985; Wantabe, 1985; Ogata and Volini, 1986; Alexander and Volini, 1987; Drawbaugh and Marrs, 1987; Aminlari et al., 1989). This enzyme catalyzes the reaction of a thiophilic anion such as cyanide and a sulfane-containing one such as thiosulfate to form a thiolated anion such as thiocyanate (Westely, 1973). Evidence has been accumulated to indicate that this enzyme plays a central role in cyanide detoxification (Frankenberg, 1980; Westely, 1981; Westely et al., 1983; Calabrese, 1983). Activity of this enzyme has been detected in homogenates from many tissues of human and other species, albeit in different amounts (Himwich and Saunders, 1948; Koj and Frendo, 1962; Wood, 1975; Dudeck et al., 1980; Drawbaugh and Marrs, 1987; Aminlari et al., 1989). It seems likely that variation in the level of this enzyme might cause interspecies difference in cyanide sensitivity and there is some evidence that this phenomenon indeed exists (Calabrese, 1983; Amin- lari et al., 1989). Comparative studies of the data published by different laboratories are difficult because of the difference in methodological approaches in the deter- mination of rhodanese activity and preparation of tissue extracts. For example, many investigators con- :~Author to whom correspondence should be addressed. sider liver and kidney of animals as the major source of rhodanese and therefore the main site of cyanide detoxification (Westely, 1973; Dudeck et al., 1980; Drawbaugh and Marrs, 1987). However, we have recently provided evidence that in ruminants the epithelial layer of different parts of stomach contains greater rhodanese activity than liver (Aminlari et al., 1989). It would be valuable to obtain more concise and accurate data on the pattern of the distribution of rhodanese in different tissues of animals. Such data might assist us to define a plausible physio- logical mechanism for cyanide detoxification medi- ated by rhodanese. In the present paper we report on the results of comparative studies on the distri- bution of rhodanese in different tissues of domestic animals. MATERIALSAND METHODS All chemicals were of analytical grade and were supplied by commercial sources. Organs of sheep (Ovis aries), camel (Camelus dromedarius) and cattle (Bos taurus) were obtained from slaughtered animals. Post-mortem horse (Equus caballus), donkey (Equus asinus), and dog (Canis familiaris) samples were obtained from the Veterinary School hospital. These samples were prepared by autopsy of animals, 0-2 hr after death. All samples, kept on ice, were transferred within 45 min to the laboratory; tissues were separated, stripped from fat and extraneous materials, washed a few times with physiological saline and then blotted. Tissue extracts were prepared by freezing 1 g of the sample in liquid nitrogen, homogenizing with a hand homogenizer, and suspending the homogenates in 4 ml of 0.025 M sodium phosphate buffer, pH 7.2. The suspensions were centrifuged for 15 min at 4000g in a MSE high speed refrigerated centrifuge. The supernatants were used as the source of enzyme. The muscular and epithelial layers of different parts of stomach and small and large intestine were 673