高血圧自然発症ラット脳動脈内皮細胞の微細変化

SCANNING ELECTRON MICROSCOPIC STUDY OF THE ENDOTHELIAL CELLS OF THE CEREBRAL ARTERIES IN THE SPONTANEOUSLY HYPERTENSIVE RATS

I．はじめに

　Okamoto＆Aoki^9）により分離された高血圧自然発症ラットSpontaneously hypertensive rat （以下SHRと省略）は，すべての動物において高血圧を自然に発症し，諸臓器に種々の高血圧性血管病変を示すので，ヒトの本態性高血圧症研究の最適のモデルとされている^3）。

　これまでに，高血圧性脳血管病変の成立機序を明らかにするために，種々の形態学的検索方法を用いて，SHR脳血管の経時的な研究がなされてきた^1,2,6,7）。その結果，高血圧に基づく脳動脈内皮細胞の機能的・器質的変化と，それによる透過性の亢進が，脳血管そのものの病変および脳実質病変を起こすのに重要な役割を演じていると考えられる所見が報告されている^2,6）。本研究は，SHR脳動脈の内皮細胞内腔表面の変化を走査型電子顕微鏡を用いて観察し，脳動脈内皮細胞に関するより広範な，またより詳細な情報を得ようとするものである。

In order to clarify the developmental mechanism of the hypertensive cerebrovascular changes mor-phologically, endothelial luminal surfaces of the cerebral arteries in spontaneously hypertensive rats (SHR) and control Wistar Kyoto rats were investi-gated by the scanning electron microscope (SEM), and following findings were obtained.

1) In control Wistar Kyoto rats, endothelial cells of the cerebral arteries showed increased number of villi and enlargements at the sites of branchings.

2) In the cerebral arteries of SHR, enlargements of endothelial cells and increased number of villiand pits which indicate an increased cellular functions of the cells were diffusely observed besides at the sites of branchings.

3) In the cerebral arteries of SHR, especially in the aged group, there were the regressive changes of the endothelial cells such as balloon-like pro-trusions, crater-like cave-ins and their transitional changes between these findings.

4) Endothelial cells with such regressive changes posessed particularly an increase of pits in number, and it was suggested that an increased vesicular transport of endothelial cells play an important role in the development of these regressive changes.

5) Aggregate of platelets was often observed adhered on endothelial luminal surfaces of the cerebral arteries in aged SHR which seems to be related to thrombus formation.

6) Markedly developed and irregularly formed marginal folds at the endothelial cell borders were observed, but the function of these folds was unknown.

7) Developmental mechanisms of various endo-thelial changes of the cerebral arteries in SHR and the relationship between these endothelial changes and hypertensive cerebrovascular changes were discussed.