酒精投與 및 禁斷이 白鼠 腦 및 肝 Adenosine Triphosphatase 活性에 미치는 影響

The Effects of Ethanol Administration and Its Withdrawal on the Activity of Adenosine Triphosphatase in Rat Brain and Liver

The major action sites of alcohol are brain and liver, though it is not still clarified how the changes affect on the formation of tolerance and dependence. Recently proposed, alcohol primarily acts on the synaptic membranes, causing widespread changes in neurotransmission via effects on the numerous biochemical processes. That is to say, alcohol inhibits action potentials and active transports of cations, in which ATPase plays an important role as a carrier. The activities of membrane-bound enzymes such as Mg++ ATPase and(Na+ — K+) ATPase are influenced by alcohol. The authors investigate on the changes of ATPase activities when ethanol is administered acutely, chronically upto 3 weeks, and withdrawn 6 hours after the last dose of ethanol upto 72 hours, to account with the effect of ethanol on sodium pump and cation transport. The results obtained are as follows: 1) Upon acute ethanol(3 0% w /v) administration, brain homogenates showed more significantly increased Mg++ ATPase activities than control group only in small amount of ethanol treated groups after 1hour and 2hours. (Na+ — K+) ATPase activities were in decreasing trend rather than the control group, even though amount of ethanol was increased and reaction line was prolonged, but there was no statistical significance. After 1 hour, only (N a+ — K+) ATPase activities were gradually decreased according to the increase of ethanol amount in liver homogenates, which were significantly decreased rather than control groups alter 2 hours. 2) Upon chronic ethanol(14% w/v)administration, brain homogenates showed significantly increased Mg++ ATPase activities in 2 weeks and 3 weeks group as increase of(Na+-K+) ATPase activities in 3weeks group. In liver homogenates, Mg++(Na+ ~ K+) ATPase and Mg++ ATPase activities were significantly increased than controls according to lapse of time, but(Na+ 一K+) ATPase activities were significantly decreased. 3) Upon ethanol withdrawal after chronic ethanol(14%w/v) administration for 3weeks ,brain homogenates showed that Mg++(Na+ — K+) ATPase activities began to decrease significantly than chronic ethanol treated groups after 12 hours of withdrawal, which was approximated to the control leveL(Na+ -K+) ATPase activities began to increase after 6 hours,reaching to the maximal level after 24 hours, which was followed by slight decrease after 48 hours and reincrease after 72 hours, being approximated to normal control group. In liver homogenates, Mg++ (Na+ - K+) ATPase activities showed no significant changes than 3 weeks ethanol treated groups with lapse of withdrawal time, but began to decrease after 6 hours, being significantiy increased after 24 hours than normal con-trols. Mg++ ATPase activities began to decrease gradually after 6 hours according to lapse of time, but it was significantly increased than normal controls. (Na+—K**) ATPase activities were gradually increased according to lapse of withdrawal time. The aforementioned findings suggest that sodi- um — pump seems to be suppressed when ethanol is administered acutely or chronically, because{Na+一 K+) ATPase activities in liver homogenates are decreased and liver weight is increased, although. acute ethanol administration cannot affect on the(Na+ - K+) ATPase activities. In brain, (Na+ 一K+) ATPase activities are decreased according to prolongation of duration of ethanol administration, and brain weight become slightly increased in l~2weeks with no changes in 3 weeks group, which suggest that sodium pump may be decreased and cation transports are inhibited. Upon lapse of ethanol withdrawal time, brain and liver (Na + - K+) ATPase activities are increased to return to the normal control level, which suggest that a certain compens