Induction of tissue angiotensin Ⅱ-forming activity in two-kidney, one-clip hypertensive hamster model

AIM: To evaluate the role of chymase in blood pressure regulation and its actions on tissue renin-angiotensin system.METHODS: A two-kidney, one-clip(2K1C) hypertension model was developed in Syrian hamsters, which have a human-type chymase. Either an angiotensin(Ang) converting enzyme(ACE) inhibitor(ACE-I; temocapril, 30 mg/kg per day), Ang Ⅱ type 1 receptor antagonist(ARB; CS866, 10 mg/kg per day), or vehicle was administered, beginning 2 wk after renal artery clipping and continued for 16 wk. At the end of this protocol, hearts, aortas, and lungs were removed, and total Ang Ⅱ-forming activities and ACE- and chymasedependent Ang Ⅱ-forming activities were determined.RESULTS: After renal artery clipping, systolic blood pressure in the vehicle group was significantly higher compared with that in a sham-operated group throughoutthe experimental period. Both ACE-I and ARB treatments revealed similar antihypertensive effects. Moreover, in the vehicle group, cardiac total and chymase-dependent Ang Ⅱ-forming activities significantly increased at 18 wk after clipping. Further, cardiac total and chymase-dependent Ang Ⅱ-forming activities decreased significantly after ACE-I or ARB treatment for 16 wk. In addition, chymase-dependent Ang Ⅱ-forming activity significantly increased in the aorta, although these changes were inhibited only by ARB. ARB treatment was more effective compared with ACE-I treatment in reversing the changes in tissue Ang Ⅱ formation, particularly in the aorta, despite their similar antihypertensive effects.CONCLUSION: Chymase does not play a major role in maintaining blood pressure and tissue ACE and chymase are regulated in a tissue-dependent manner in 2K1 C hamster.

Prevalence and Characteristics of Treatment-Resistant Hypertension among Hypertensive Japanese Outpatients

Aims: To retrospectively investigate the prevalence and characteristics of treatment-resistant hypertension (R-HT) among consecutive hypertensive outpatients, since patients with R-HT are candidates for catheter-based renal sympathetic denervation (RD). Methods: Consecutive hypertensive outpatients (n = 999) were recruited in our hospital. R-HT patients who were candidates for RD had clinic systolic blood pressure > 160 mmHg despite taking three or more antihypertensive drugs including at least one diuretics at higher than standard doses. Results: Our survey indicated that only 26 patients (2.6%) were potential candidates for renal denervation. Candidates for RD showed a significantly higher age (P < 0.005), brain natriuretic peptide level (P = 0.0001), urinary albumin/creatinine excretion ratio in spot urine (P < 0.005), pulse wave velocity (P < 0.01), left ventricular end-diastolic diameter (P < 0.005), and interventricular septal thickness (P < 0.005) than the other 973 patients. Candidates for denervation had a significantly lower hemoglobin (P = 0.0001), serum albumin (P < 0.001), eGFR (P < 0.0005), plasma renin activity (P = 0.0001), and plasma aldosterone level (P < 0.005) than other patients, while their urinary sodium/creatinine ratio was higher, indicating that patients with R-HT appeared to have a high salt intake. Conclusion: Our retrospective clinical survey indicated that only 0.5% of Japanese hypertensive outpatients (5/999 patients) were candidates for RD. Therefore, establishment of hypertension cohort network will be essential to recruit R-HT patients for RD.