川崎 晃一

イワシタンパク質由来ペプチドならびに Valyl-Tyrosine の降圧作用-高血圧自然発症ラットに対する効果-

J Jpn Soc Nutr Food Sci 52: 271-277 (1999) The antihypertensive effect of peptides (Y-2) derived from sardine, valyl-tyrosine and -mixture (MIX) of four dipeptides having angiotensin converting enzyme inhibitory activity was studied in spontaneously hypertensive rats (SHR) .1) Single oral administration of Y-2, valy1-tyrosine and MIX lowered the systolic blood pressure in SHR, and its minimum effective doses were 10, 1, and 10 mg/ kg, respectively. These effects lasted for 8 h after administration. The hypotensive potency of valy1-tyrosine was greater than those of Y-2 and MIX. Valy1-tyrosine (1 and 10 mg/kg) lowered the blood pressure dose-dependently. 2) When 1000, 10, and 10 mg of Y-2, valy1-tyrosine and MIX, respectively, were administered orally to the SHR twice a day for 10 consecutive days, any of the regimens decreased systolic blood pressure significantly, and the decrement of systolic blood pressure continued for 5 days thereafter. These results indicate that either Y-2, valy1-tyrosine or MIX can exert a potent and long-lasting antihypertensive effect in SHR.

125I-アルドステロンキット (ALDOCTK-125KIT) による尿中アルドステロン測定の基礎的検討ならびにその臨床応用

A method of radioimmunoassay for urinary aldosterone excretion (AER) using 125I-labeled ligand [ALDOCTK-125KIT] is described. The sensitivity, specificity, reproducibility and accuracy of this method were compared with the 3H-RIA method previously reported. Since the extraction method using ALDOCTK-125KIT was considered to be preferable to the direct method, the former method was applied to the present study. An excellent correlation was found between the values determined by the 3H-RIA method and the extraction method (r = 0.935, p less than 0.001, Y = 0.89X + 0.80, n = 146). The within-assay and the between-assay coefficient of variation was 7.7--15.0% and 9.7--12.2%, respectively. As a clinical application, the circadian variation of AER was investigated in 5 control subjects and groups of essential hypertension (EHT), primary aldosteronism (PA), chronic glomerulonephritis (CGN) and Cushings syndrome, each of which consisted of 5 patients, all of which had serum creatinine concentrations of less than 1.2 mg/dl. Under a control diet containing 10 g of salt per day, urine was collected in 4-hour pools starting at 8:00 for the ensuing 24 hours, and AER was determined by means of both 3H-RIA and the extraction method. The difference of the values between the peak and the nadir in each subject was statistically significant, and marked and identical circadian variations of AER with the peak and the nadir at the period of 4:00 to 12:00 and 20:00 to 4:00 were observed in the control, EHT, PA and CGN groups. In the Cushing group, however, the circadian variation of AER was different from the other 4 groups: the peak and the nadir of AER occurred at the period of 20:00 to 24:00 and 4:00 to 8:00, respectively. The circadian variation of AER became more obvious in all groups including the Cushing, when each value was expressed in the percentage of the mean. AER under the control diet was 9.38 +/- 2.04 micrograms/day in the control subjects. In PA and CGN, AER was significantly higher, and in the Cushing group, it was significantly lower than that observed in the control. However, no difference was found in AER between the control and EHT. AERs in both 4-hour and 24-hour urine specimens measured by ALDOCTK-125KIT were consistent with those by the 3H-RIA method.