Abstract
The binding in vitro of an opiate agonist, $(^3H)-morphine$, was studied using rat brain slices which were incubated in the modified Krebs-Henseleit bicarbonate buffer solution containing various concentrations of electrolytes with or without morphine, naloxone or morphine+naloxone at $4^{\circ}C$ for 24 hours. The binding of $(^3H)-morphine$ may be seperated into two component; one a saturable binding and the other nonsaturable. The saturable binding may be calculated from the differences in binding observed in the absence and presence of high concentration of morphine. The maximal saturable binding and $K_D$ value in the naive preparations were $0.32{\pm}0.02\;pmole/mg$ protein and $0.75{\pm}0.07\;nM$ respectively. The saturable binding of $(^3H)-morphine$ was significantly increased by low temperature-treatment, while $K_D$ value was not changed. Morphine in the incubation media significantly increased the saturable binding of $(^3H)-morphine$ and $K_D$ value. Naloxone also increased the maximal saturable binding of $(^3H)-morphine$ and $K_D$ value of the drug. Decrease of $K^+\;and\;Mg^{++}$, and addition of $Mn^{++}$ in the incubation media significantly increased the saturable binding of $(^3H)-morphine$, but decrease of $Na^+$and increase of $Ca^{++}$ in the incubation media did not influence the binding. The increment of the saturable binding of $(^3H)-morphine$ by nonlabeled morphine in the incubation media was notaffected by decrease of $Na^+,\;K^+\;or\;Mg^{++}$, or addition of $Mn^{++}$ into the incubation media, but was inhibited by increase of $Ca^{++}$ in the incubation media, while the increment of the saturable binding of $(^3H)-morphine$ was net observed by decrease of $Na^+,\;K^+\;or\;Mg^{++}$, or increase of $Ca^{++}$ in the incubation media. The above results indicate that change of opiate binding sites in quality, i.e. affinity, and quantity, i.e. number of binding sites, may occur by low temperature-treatment in the absence and presence of morphine or naloxone and that electrolytes play role of the changes of opiate binding sites.
전해질농도(電解質濃度)를 달리하고 morphine, naloxone 또는 morphine+naloxone을 가(加)하거나 가(加)하지 않은 modified Krebs-Henseleit bicarbonate buffer용액(溶液)에 흰쥐의 뇌절편(腦切片)을 incubate하여 저온처리(低溫處理)와 media내(內) 전해질조성(電解質組成)이 $(^3H)-morphine$의 saturable binding에 미치는 영향(影響)을 관찰(觀察)하여 다음과 같은 성적(成績)을 얻었다. 1) 저온처리(低溫處理)는 $(^3H)-morphine$의 saturable binding을 현저(顯著)히 증가(增加)시켰고, maximal saturable binding은 증가(增加)시키나 $K_D$치(値)에는 영향(影響)을 미치지 못하였다. 2) 저온처리시(低溫處理時) media내 morphine과 naloxone은 $(^3H)-morphine$ 의 maximal saturable binding 과 $K_D$치(値)를 증가(增加) 시켰다. 3) 저온처리시(低溫處理時) media내(內) $K^+$감소(減少), $Mg^{++}$제거 또는$Mn^{++}$첨가(添加)는 $(^3H)-morphine$의 saturable binding을 현저(顯著)히 증가(增加)시켰고, $Na^+$감소(減少), $Ca^{++}$증가(增加)는 saturable binding에 영향(影響)을 미치지 못하였다. 4) 저온처리시(低溫處理時) media내(內) morphine에 의한 $(^3H)-morphine$의 saturable binding증가(增加)는 media내(內) $Na^+$감소(減少), $K^+$감소(減少), $Mg^{++}$제거 또는 $Mn^{++}$첨가(添加)로는 영향(影響) 받지 않았으나 $Ca^{++}$증가(增加)로 억제(抑制)되었고, media내(內) naloxone에 의한 saturable binding증가(增加)는 $Mn^{++}$첨가(添加)는 영향(影響)받지 않았으나 media내(內) $Na^+$감소(減少), $K^+$감소(減少), $Ca^{++}$증가(增加) 또는 $Mg^{++}$제거로 억제(抑制)되었다. 이상(以上) 실험성적(實驗成績)은 저온처리(低溫處理) 및 저온처리시(低溫處理時) media내(內) morphine 또는 naloxone이 opiate수용체(受容體)의 양적(量的)인 변동(變動)과 또는 친화력(親和力)의 변동(變動)을 유발(誘發)하며, media내(內) 전해질조성(電解質組成)이 이들 변동(變動)에 영향(影響)을 미침을 시사(示唆)한다.
(Dept. of Pharmacology, Jeonbug University Medical School)
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