Ward P E, Johnson A R
Biochem J. 1978 Apr 1;171(1):143-8. doi: 10.1042/bj1710143.
The activity and distribution of substance P-catabolizing enzyme(s) were studied in the rat kidney. Kidney homogenates inactive substance P 5-20 times as fast as do homogenates of intestine, liver, lung, heart or brain. The catabolizing activity was highest in the cortex and decreased progressively down the papilla. Cortex of rat kidney was homogenized and fractions enriched in microsomal membrane, final supernatant, plasma membrane, endoplasmic reticulum, brush border and intact glomeruli were prepared. The identity and homogeneity of the preparations were determined by assaying marker enzymes and by morphological examination. Substance P was catabolized most rapidly by the microsomal and plasma-membrane-enriched fractions, and least rapidly by endoplasmic reticulum or final supernatant fractions. Purified brush border of proximal tubules inactivated substance P more than 10 times as fast as isolated glomeruli. Our experiments show that substance P is catabolized at a rate that is similar to the rates of inactivation of bradykinin and angiotensin II. Further, the distribution of substance P-catabolizing activity in various kidney fractions is similar to the distribution of kininase and angiotensinase activities previously reported.
对大鼠肾脏中P物质分解代谢酶的活性和分布进行了研究。肾脏匀浆使P物质失活的速度比肠、肝、肺、心脏或脑的匀浆快5至20倍。分解代谢活性在皮质中最高，并沿乳头逐渐降低。将大鼠肾脏皮质匀浆，制备富含微粒体膜、最终上清液、质膜、内质网、刷状缘和完整肾小球的组分。通过测定标记酶和形态学检查来确定制备物的同一性和均一性。P物质被富含微粒体和质膜的组分分解代谢得最快，而被内质网或最终上清液组分分解代谢得最慢。近端小管纯化的刷状缘使P物质失活的速度比分离的肾小球快10倍以上。我们的实验表明，P物质的分解代谢速率与缓激肽和血管紧张素II的失活速率相似。此外，P物质分解代谢活性在各种肾脏组分中的分布与先前报道的激肽酶和血管紧张素酶活性的分布相似。
