Vieira M A, Moreira M F, Maack T, Guimarães J A
Department of Physiology and Biophysics, ICB, Universidade Federal de Minas Gerais, Brazil.
Biochem Pharmacol. 1994 Apr 29;47(9):1693-9. doi: 10.1016/0006-2952(94)90549-5.
Isolated rat kidneys were perfused with T-kinin (TK, Ile-Ser-BK) and bradykinin (BK). HPLC analysis of perfusate samples taken at 2-10 min during the TK perfusion (0.5 nmol/mL initial concentration) showed two peptide peaks, the first one eluting at 14.42 min, the same retention time for standard BK, and the second at 16.20 min, corresponding to that of TK. When BK (0.5 nmol/mL) was perfused, only its corresponding peak was obtained although total BK recovery was reduced quickly, as expected. Using both HPLC analysis and a kinin bioassay on the isolated guinea pig ileum, it was found that 12% of the added TK was converted to BK during the first perfusion cycle (2 min). While the BK recovered (12-14% from the initial TK concentration) was maintained at a similar proportion between the 2nd and the 10th min of perfusion, the rate of TK disappearance, as well as its full recovery from the perfusate, indicated further fragmentation of peptides during kinin perfusion. In the presence of 5 microM DL-mercaptomethyl-3-guanidino-ethylthiopropanoic acid (Mergetpa), an inhibitor of plasma carboxypeptidase N (EC 3.4.17.3), the rate of conversion of TK to BK was not affected. On the other hand, the kinase II inhibitor bradykinin potentiating peptide 9a (BPP9a) increased both the proportion of TK converted to BK and the disappearance rate of TK from the perfusate. In the presence of BPP9a, the rate of BK production increased from 1.5 +/- 0.2 to 7.6 +/- 0.9 nmol/min. Furthermore, the recovery of BK was reduced during the first 2 min of perfusion to 7.6% and the conversion rate to 0.9 nmol/min when TK was perfused into the kidney in the presence of 10 microM bestatin, a known inhibitor of aminopeptidases. These data indicate that in the kidney TK is converted to BK, probably by aminopeptidase M, thus suggesting that BK is, in fact, an additional and functional kinin, inducing physiological and/or pathophysiological effects in the rat kidney in which TK is the main kinin released.
用T-激肽（TK，异亮氨酸-丝氨酸-缓激肽）和缓激肽（BK）对离体大鼠肾脏进行灌注。在TK灌注（初始浓度0.5 nmol/mL）期间2至10分钟采集的灌注液样品的HPLC分析显示有两个肽峰，第一个峰在14.42分钟洗脱，与标准BK的保留时间相同，第二个峰在16.20分钟洗脱，与TK的保留时间相对应。当灌注BK（0.5 nmol/mL）时，尽管如预期的那样总BK回收率迅速降低，但仅获得了其相应的峰。通过HPLC分析和对离体豚鼠回肠的激肽生物测定发现，在第一个灌注周期（2分钟）内，添加的TK中有12%转化为BK。虽然回收的BK（占初始TK浓度的12 - 14%）在灌注的第2分钟至第10分钟之间保持相似的比例，但TK的消失速率以及其从灌注液中的完全回收率表明在激肽灌注期间肽进一步断裂。在存在5 microM DL-巯基甲基-3-胍基-乙基硫代丙酸（Mergetpa，一种血浆羧肽酶N（EC 3.4.17.3）的抑制剂）的情况下，TK向BK的转化速率不受影响。另一方面，激酶II抑制剂缓激肽增强肽9a（BPP9a）增加了TK转化为BK的比例以及TK从灌注液中的消失速率。在存在BPP9a的情况下，BK的产生速率从1.5±0.2增加到7.6±0.9 nmol/分钟。此外，当在存在10 microM贝司他汀（一种已知的氨肽酶抑制剂）的情况下将TK灌注到肾脏中时，BK在灌注的前2分钟内的回收率降低至7.6%，转化速率降低至0.9 nmol/分钟。这些数据表明在肾脏中TK可能通过氨肽酶M转化为BK，因此表明BK实际上是一种额外的功能性激肽，在大鼠肾脏中诱导生理和/或病理生理效应，其中TK是释放的主要激肽。
