Hypertension-attenuating effect of whey protein hydrolysate on spontaneously hypertensive rats

The angiotensin I-converting enzyme (ACE)-inhibitory activity and antihypertensive effect of whey protein hydrolysate (WPH) after single oral administration (short term) or continuous administration for 20 d (long term) were investigated. In the case of short term administration, the systolic and diastolic blood pressure of spontaneously hypertensive rats (SHRs) in captopril and WPH-supplemented groups significantly decreased from 6 to 8 h post-administration compared to the negative control group. In the case of long term administration, WPH supplementation lowered the blood pressure and affected the heart rate of SHRs in a dose-dependent manner, the lowest systolic blood pressure was obtained at the dose of 240 mg WPH/kg b.w. Furthermore, the ACE activity in plasma, lung, kidney and abdominal aorta of the WPH-administered groups decreased in a dose-related manner, and was significantly lower than that of the negative control group. These results suggest that WPH with an ACE-inhibitory activity could potentially suppress the development of hypertension in SHRs.