Wallis C J, Gregory T J, Printz M P
J Neurochem. 1982 Jul;39(1):111-6. doi: 10.1111/j.1471-4159.1982.tb04708.x.
Prior studies from this laboratory have established that angiotensinogen, the prohormone of angiotensin, is unevenly distributed in the rat brain and that adrenalectomy selectively perturbs levels of the prohormone in regions associated with cardiovascular neural pathways. However, plasma angiotensinogen levels are 10(2)--10(3) times higher in plasma than in brain, so that the observation of a unique distribution of brain angiotensinogen may reflect variable plasma contamination. Studies were therefore undertaken to establish whether adrenalectomy selectively alters regional blood flow, blood volume, or plasma contamination of brain tissue, thereby artifactitiously altering apparent angiotensinogen levels. Radioactive 2-deoxyglucose, iodoantipyrine, and inulin were employed in these analyses. We conclude that variations in blood flow do not explain the selective effects of adrenalectomy, but that a variable extent of residual plasma contamination (remaining after transcardiac perfusion) is partially reflected in our earlier data. However, after correcting for plasma contamination, we still find significant changes in selected areas of the rat brain following adrenalectomy. Finally, our results demonstrate the necessity for direct quantitation of plasma contamination od brain tissue segments. This is shown to have relevance in other situations, such as corticosterone binding globulin contamination of brain corticosterone receptor binding.
该实验室先前的研究已证实，血管紧张素原（血管紧张素的前体激素）在大鼠脑中分布不均，并且肾上腺切除术会选择性地扰乱与心血管神经通路相关区域的前体激素水平。然而，血浆中血管紧张素原的水平比脑中高10² - 10³倍，因此观察到的脑内血管紧张素原独特分布可能反映了不同程度的血浆污染。因此开展了研究以确定肾上腺切除术是否会选择性地改变脑血流量、血容量或脑组织的血浆污染，从而人为地改变血管紧张素原的表观水平。这些分析中使用了放射性2-脱氧葡萄糖、碘安替比林和菊粉。我们得出结论，血流量的变化并不能解释肾上腺切除术的选择性作用，但残留血浆污染程度的差异（经心脏灌注后残留）在我们早期的数据中部分有所体现。然而，校正血浆污染后，我们仍发现肾上腺切除术后大鼠脑的某些选定区域有显著变化。最后，我们的结果表明有必要直接定量脑组织片段中的血浆污染。这在其他情况下也有相关性，比如脑皮质酮受体结合的皮质酮结合球蛋白污染。
