methylthiouracil and sodium-perchlorate

Na,K- and Ca,Mg-ATPase activities in the membrane of red blood cells (RBC) were determined in glutamate treated obese rats (GOR). Both activities are related oppositely. In the obese rats the Na,K-ATPase is higher but the efficiency in maintenance of Na/K-ion concentration gradients is diminished. Ca,Mg-ATPase is decreased in GOR. Under the hypermetabolic condition of cold adaption the Na,K-ATPase activity decreases and the Ca,Mg-ATPase activity rises in both animal groups. The Na,K-ATPase activity in RBC-membranes is positively related to fat accumulation and age.

Topics: Animals; Ca(2+) Mg(2+)-ATPase; Calcium-Transporting ATPases; Cold Temperature; Erythrocyte Membrane; Female; Male; Methylthiouracil; Obesity; Perchlorates; Rats; Sodium Compounds; Sodium Glutamate; Sodium-Potassium-Exchanging ATPase

The effect of sodium perchlorate (NaClO4) on the methylthiouracil-induced increase in the activity of thyroid glucose 6-phosphate dehydrogenase (G6PDH), ornithine decarboxylase (ODC) and polyamine contents was studied in the rat. The G6PDH activity was increased nearly three-fold by methylthiouracil (MTU) but not by ClO4- at 7 days of treatment. Perchlorate lowered the MTU-induced enzyme activity to nearly the control level, without changing circulating thyrotrophin (TSH). The anion had no inhibitory effect on G6PDH activity in vitro. The possibility that an inhibitor specific for G6PDH was generated in ClO4- - treated rat thyroids was excluded. The activity of ODC was greatly increased by both ClO4- and MTU, the increase being significant as early as on the second day of treatment. Perchlorate had no inhibitory effect on MTU-induced ODC activity in vivo but decreased total contents of spermidine and spermine in the thyroid, without affecting the concentration (nmoles/g wet weight) of the polyamines. These results suggest that ClO4- acts directly on the thyroid to suppress specifically the stimulatory effect of TSH on G6PDH activity and possibly on polyamine accumulation.

Topics: Animals; Antithyroid Agents; DNA; Glucosephosphate Dehydrogenase; Male; Methylthiouracil; Organ Size; Ornithine Decarboxylase; Perchlorates; Polyamines; Putrescine; Rats; RNA; Sodium Compounds; Spermidine; Spermine; Thyroid Gland; Thyrotropin