Comprehensive studies on the renal kallikrein-kinin system in essential hypertension.

In order to investigate the role of the renal kallikrein-kinin (K-K) system in normal (NRH) and low renin (LRH) subgroups of essential hypertension (EHT), daily urinary excretions of renal K-K system components including kallikrein (KAL), total KAL, pre-KAL, kinin (KIN) and kininase (total, I and II), were measured in 21 normotensives (NT) and 45 patients with EHT (NRH: 29, LRH: 16). Urinary KAL and KIN quantities, KAL activity, total and pre-KAL, and kininase (total, I and II) were measured by direct RIA, kininogenase assay, direct RIA of KAL after trypsin treatment, and KIN destroying capacity, respectively. The daily excretions of KAL quantity and activity, total and pre-KAL, and KIN were significantly lower in EHT than in NT. That of total kininase and kininase I were significantly higher in EHT than in NT while no significant difference was found in kininase I between EHT and NT. In comparing NRH and LRH, the urinary KAL activity and KIN were lower in LRH than in NRH, and kininase I was higher in LRH than in NRH. No significant difference, however, was found in total and pre-KAL, KAL quantity and kininase II between NRH and LRH. The ratio of KAL quantity/total KAL which reflects the conversion rate from pre-KAL in the kidney, did not show any significant difference among NT, NRH and LRH.(ABSTRACT TRUNCATED AT 250 WORDS)