Isoleucine-tryptophan, whey protein hydrolysate, and captopril effectively blunted systolic blood pressure rise in hypertensive rats (-42 ± 3, -38 ± 5, and -55 ± 4 mm Hg vs. placebo, respectively).
Does isoleucine-tryptophan or whey protein hydrolysate reduce systolic blood pressure in spontaneously hypertensive rats?
Whey protein hydrolysate and isoleucine-tryptophan inhibit plasma ACE and attenuate hypertension in spontaneously hypertensive rats, suggesting potential as food additives.
AIMS: Angiotensin-converting enzyme inhibitors are treatment of choice in hypertensive patients. Clinically used inhibitors exhibit a structural similarity to naturally occurring peptides. This study evaluated antihypertensive and cardioprotective effects of ACE-inhibiting peptides derived from food proteins in spontaneously hypertensive rats. METHODS AND RESULTS: Isoleucine-tryptophan (in vitro IC50 for ACE = 0.7 μm), a whey protein hydrolysate containing an augmented fraction of isoleucine-tryptophan, or captopril was given to spontaneously hypertensive rats (n = 60) over 14 weeks. Two further groups, receiving either no supplement (Placebo) or intact whey protein, served as controls. Systolic blood pressure age-dependently increased in the Placebo group, whereas the blood pressure rise was effectively blunted by isoleucine-tryptophan, whey protein hydrolysate and captopril (-42 ± 3, -38 ± 5, -55 ± 4 mm Hg vs. Placebo). At study end, myocardial mass was lower in isoleucine-tryptophan and captopril groups but only partially in the hydrolysate group. Coronary flow reserve (1 μm adenosine) was improved in isoleucine-tryptophan and captopril groups. Plasma ACE activity was significantly decreased in isoleucine-tryptophan, hydrolysate and captopril groups, but in aortic tissue only after isoleucine-tryptophan or captopril treatment. This was associated with lowered expression and activity of matrix metalloproteinase-2. Following isoleucine-tryptophan and captopril treatments, gene expression of renin was significantly increased indicating an active feedback within renin-angiotensin system. CONCLUSION: Whey protein hydrolysate and isoleucine-tryptophan powerfully inhibit plasma ACE resulting in antihypertensive effects. Moreover, isoleucine-tryptophan blunts tissue ACE activity, reduces matrix metalloproteinase-2 activity and improves coronary flow reserve. Thus, whey protein hydrolysate and particularly isoleucine-tryptophan may serve as innovative food additives with the goal of attenuating hypertension.
Martin et al. (Sat,) conducted a other in Hypertension (spontaneously hypertensive rats) (n=60). Isoleucine-tryptophan, whey protein hydrolysate, or captopril vs. Placebo or intact whey protein was evaluated on Systolic blood pressure. Isoleucine-tryptophan, whey protein hydrolysate, and captopril effectively blunted systolic blood pressure rise in hypertensive rats (-42 ± 3, -38 ± 5, and -55 ± 4 mm Hg vs. placebo, respectively).