Mansner R
Med Biol. 1977 Aug;55(4):228-33.
The in vitro uptake of nicotine into the crude synaptosomal fraction of rat brain and spinal cord was studied. The tissue/midium ratio was low and the changing of incubation time or [14C]nicotine concentration did not affect the ratio, nor did a metabolic inhibitor, sodium fluoride. A lowered ratio was obtained at 0degrees C, but this decrease may be attributable to an altered pKa of the drug at low temperature. Nicotine antagonists, mecamylamine and hexamethonium, did not affect the ratio when incubating the crude synaptosomal fraction of either adult or infant rat brain. These results suggest that the uptake of nicotine into the synaptomal fraction is not an active process. When mecamylamine and nicotine were injected in vivo, the mecamylamine antagonism was also demonstrated as lowered nicotine concentrations in infant ray synaptosomes. Since the newborn rat cortex lacks glial tissue, the nicotine concentrations in the crude synaptosomal fraction of infant rats may reflect the receptor level effects better than in adult brains. The pretreatment of infant rats with mecamylamine also lowered blood nicotine levels, suggesting that mecamylamine affected nicotine brain levels also in an unspecific way.
研究了尼古丁在大鼠脑和脊髓粗突触体部分的体外摄取情况。组织/介质比值较低，孵育时间或[14C]尼古丁浓度的变化均不影响该比值，代谢抑制剂氟化钠也不影响。在0℃时比值降低，但这种降低可能归因于低温下药物pKa的改变。尼古丁拮抗剂美加明和六甲铵在孵育成年或幼鼠脑粗突触体部分时不影响该比值。这些结果表明尼古丁摄取到突触体部分不是一个主动过程。当在体内注射美加明和尼古丁时，美加明的拮抗作用也表现为幼鼠突触体中尼古丁浓度降低。由于新生大鼠皮层缺乏神经胶质组织，幼鼠粗突触体部分中的尼古丁浓度可能比成年大脑更好地反映受体水平效应。用美加明预处理幼鼠也降低了血液中的尼古丁水平，这表明美加明也以非特异性方式影响尼古丁的脑内水平。
