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Effects of benzo(a)pyrene exposure on the ATPase activity and calcium concentration in the hippocampus of neonatal rats

100%

Yang K. , Chen C. , Cheng S. , Cao X. , Tu B.

tom 30

nr 2

203-211

Objectives To investigate whether postnatal benzo(a)pyrene (B(a)P) exposure caused the impairments on the process of neurodevelopment and the alteration in the calcium medium in the neonatal rats. Material and Methods Eighty neonatal Sprague Dawley (SD) rats were randomly divided into 5 groups (untreated control group, vehicle group, 0.02 mg/kg, 0.2 mg/kg and 2 mg/kg B(a)P-exposed group). Rats were treated with B(a)P by the intragastric administration from postnatal day (PND) 4 to 25. Morris water maze (MWM) was employed to observe the spatial memory of rats. The activity of calcium adenosine triphosphatase (Ca2+-ATPase), sodium-potassium adenosine triphosphatase (Na+-K+-ATPase) and calcium-magnesium adenosine triphosphatase (Ca2+-Mg2+-ATPase) in the hippocampus were detected by commercial kits. Fura-2 pentakis(acetoxymethyl) (Fura-2/AM) probe and reactive oxygen species (ROS) reagent kit were used for measuring the concentration of Ca2+ and ROS in the hippocampus synapse, respectively. Results Rats exposed to B(a)P resulted in the deficits in the spatial memory manifested by the increased escape latency and decreased number of crossing platform and time spent in target quadrant in comparison with the control groups. Benzo(a)pyrene exposure caused the significant decrease in the ATPase activity in the hippocampus and caused Ca2+ overload in the synaptic, besides, the ROS concentration increased significantly which may further induce neurobehavioral impairment of the neonatal rats. Conclusions Our findings suggest that postnatal B(a)P exposure may cause the neurobehavioral impairments in the neonatal rats, which were mediated by the decreased ATPase activity and elevated Ca2+ concentration. Int J Occup Med Environ Health 2017;30(2):203–211

Spectrophotometric method for the determination of renal ouabain-sensitive Hplus, Kplus-ATPase activity

84%

Beltowski J. , Wojcicka G.

nr 2

The aim of this work was to develop a method for renal H+,K+-ATPase measurement based on the previously used Na+ ,K+ -ATPase assay (Bełtowski et al.: J Physiol Pharmacol.; 1998, 49: 625-37). ATPase activity was assessed by measuring the amount of inorganic phosphate liberated from ATP by isolated microsomal fraction. Both ouabain-sensitive and ouabain-resistant K+ -stimulated and Na+ -independent ATPase activity was detected in the renal cortex and medulla. These activities were blocked by 0.2 mM imidazolpyridine derivative, Sch 28080. The method for ouabain- sensitive H+ ,K -ATPase assay is characterized by good reproducibility, linearity and recovery. In contrast, the assay for ouabain-resistant H ,K -ATPase was unsatisfactory, probably due to low activity of this enzyme. Ouabain-sensitive H+ ,K+ -ATPase was stimulated by K + with Km of 0.26 ± 0.04 mM and 0.69 ±0.11 mM in cortex and medulla, respectively, and was inhibited by ouabain (Ki of 2.9 ± 0.3 uM in the renal cortex and 1.9 ± 0.4 uM in the renal medulla) and by Sch 28080 (Ki of 1.8 ± 0.5 uM and 2.5 ± 0.9 uM in cortex and medulla, respectively). We found that ouabain-sensitive H+ ,K+ -ATPase accounted for about 12% of total ouabain-sensitive activity in the Na+ ,K+-ATPase assay. Therefore, we suggest to use Sch 28080 during Na+,K+-ATPase measurement to block H+ ,K+ -ATPase and improve the assay specificity. Leptin administered intraperitoneally (1 mg/kg) decreased renal medullary Na+ ,K+ -ATPase activity by 32.1% at 1 h after injection but had no effect on H+ ,K+ -ATPase activity suggesting that the two renal ouabain-sensitive ATPases are separately regulated.

Correlation of myofibrillar ATPase activity and myosin heavy chain content in ventricular and atrial myocardium of fish heart

67%

Karasinski J. , Sokalski A. , Kilarski W.

nr 1