The effect of triethyltin on mitochondrial swelling

Inhibition of Ca2+ transport associated with cAMP-dependent protein phosphorylation in rat cardiac sarcoplasmic reticulum by triorganotins

Organotin compounds have been shown to interfere with cardiovascular system. We have studied the in vitro and in vivo effects of tributyltin bromide (TBT), triethyltin bromide (TET) and trimethyltin chloride (TMT) on the cardiac SR Ca2+ pump, as well as on protein phosphorylation of SR proteins, in order to understand the relative potency of these tin compounds. All the three tin compounds inhibited cardiac SR 45Ca uptake and Ca(2+)-ATPase in vitro in a concentration-dependent manner. The order of potency for Ca(2+)-ATPase as determined by IC50, is TBT (2 microM) greater than TET (63 microM) greater than TMT (280 microM). For 45Ca uptake, it followed the same order i.e., TBT (0.35 microM) greater than TET (10 microM) greater than TMT (440 microM). In agreement with the in vitro results, both SR Ca(2+)-ATPase and 45Ca uptake were significantly inhibited in rats treated with these tin compounds, indicating that these tin compounds inhibit cardiac SR Ca2+ transport. cAMP significantly elevated (70-80%) the 32P-binding to SR proteins in vitro in the absence of any organotin. In the presence of organotins, cAMP-stimulated 32P-binding to proteins was significantly reduced, but the decrease was concentration dependent only at lower concentrations. The order of potency is TBT greater than TET greater than TMT. In agreement with in vitro studies, cAMP-dependent 32P bound to proteins was significantly reduced in rats treated with TBT, TET and TMT. SDS-polyacrylamide gel electrophoresis of the cardiac SR revealed at least 30 Coomassie blue stainable bands ranging from 9 to 120 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)

Tin--a toxic heavy metal? A review of the literature

A tolerable limit for tin concentration in canned food of 250 ppm (Fritsch et al., 1977) is generally accepted. However, biochemical effects attributable to tin have been observed even after oral administration of 1 and 3 mg Sn/kg body wt (Yamaguchi et al., 1980). These doses reflect 10 and 30 ppm tin in the diet. The experiments of de Groot (1973) showed that hemoglobin concentrations in the blood of rats decreased significantly feeding a diet containing 150 ppm tin. The absorption of iron was diminished after simultaneous administration of 0.8 mumol Sn(II) and iron, reflecting a tin dose of 95 ppm tin, by injection into jejunal loops of rats (Schäfer and Forth, 1983). In general, however, canned food usually plays a secondary role in daily nutrition. Fortunately, concentrations of about 2000 ppm tin as reported by Warburton et al. (1962) and Barker and Runte (1972) are not found in canned food, but values between 50 and 500 ppm are not unusual (Piscator, 1979). If a large amount of canned food is eaten daily over a long period, disturbances of gastric acid secretion and a reduction in iron absorption or heme metabolism cannot be excluded. The storage of food, especially acid foods, in opened cans should be avoided as this practice increases the amount of tin in the food when it is consumed.