ABSTRACT
Objective To study the effects of 3,5-diiodotyrosine (DIT) and potassium iodide (KI) on myocardial ATPase activity in hyperthyroidism Wistar rats induced by thyroid tablets.Methods Seventy-two Wistar rats were divided into 8 groups according to body weight by the random number table method (9 rats in each group),respectively,which were control group,hyperthyroidism model group,low,medium and high doses groups (both DIT and KI contents were 25.0,166.7,500.1 μg/kg).Physiological saline was intragastrically administrated to the control group;the hyperthyroidism model group was given thyroid tablet suspension (200.0 mg/kg);DIT and KI groups were given thyroid tablet suspension with corresponding doses of iodine simultaneously.The medicine was given once a day for a mouth,all the rats were sacrificed and heart tissue was collected.The colorimetric method was used to examine the activity of ATPases (Na+-K+-ATPase,Mg2+-ATPase,Ca2+-ATPase).Results The activities of Na+-K+-ATPase,Mg2+-ATPase,Ca2+-ATPase were significantly different statistically between groups (F =2.99,3.03,6.18,all P ＜ 0.01).Compared with the control group [(4.01 ± 0.22),(4.28 ± 0.28),(4.46 ± 0.35) μmol/mg·h],the activities of ATPases (Na+-K+-ATPase,Mg2+-ATPase,Ca2+-ATPase included) were reduced significantly in hyperthyroidism model group [(3.60 ± 0.25),(3.42 ± 0.31),(3.85 ± 0.17)μ mol/mg·h,all P ＜ 0.01];the activities of Mg2+-ATPase in DIT medium dose group [(3.89 ± 0.35)μmol/mg ·h],Ca2+-ATPase in DIT medium and high doses groups [(4.12 ± 0.20),(4.09 ± 0.21)μ mol/mg·h] were reduced significantly (all P ＜ 0.05);the activities of Na+-K+-ATPases,Ca2+-ATPase were decreased significantly in three KI groups [(3.64 ± 0.32),(3.60 ± 0.32),(3.53 ± 0.33),(3.93 ± 0.22),(3.90 ± 0.23),(3.85 ± 0.26)μmol/mg·h],Mg2+-ATPase in KI high dose group [(3.65 ± 0.49)μmol/mg·h] was decreased significantly (P ＜ 0.05or ＜ 0.01).Compared with the hyperthyroidism model group,the activities of ATPase were increased in most of the DIT groups [Mg2+-ATPase in low,medium doses groups:(4.06 ± 0.51),(3.89 ± 0.35)μmol/mg·h;Ca2+-ATPase in low,medium,high doses groups (4.15 ± 0.26),(4.12 ± 0.20),(4.09 ± 0.21)μmol/mg·h,all P ＜ 0.05].Conclusion Supplementation of thyroid tablets in the process of hyperthyroidism formation in Wistar rats will reduce myocardial damage by DTT compared with the same dose of KI.