Effect of hemp seed protein isolate on mesenteric resistance artery isolated from the spontaneously hypertensive rat

Abstract

Hypertensive vessels are characterized by attenuated endothelium-dependent vascular relaxation or endothelial dysfunction. Hemp seed protein isolate (HPI) is a novel protein that contains more than 80% of crude hemp protein and exhibits antihypertensive properties. In addition, HPI contains high levels of arginine, a pre-cursor for vasodilator nitric oxide (NO). However, it is unknown whether HPI can improve the vascular function of hypertensive vessels. Also, sex differences are observed in vascular function and BP regulation, with males at greater risk as opposed to age-matched pre-menopausal women. The present study tested the hypothesis that direct treatment of HPI will lead to vascular relaxation of pre-constricted mesenteric resistance arteries. In addition, we also addressed sex differences in vascular response to HPI. To investigate the potential vasorelaxant activity, we tested HPI (0.1 to 100 µg/mL) on third-order mesenteric arteries using the pressure myography technique. We found that HPI relaxed mesenteric resistance arteries isolated from 16-week-old male and female Sprague Dawley (SD), spontaneously hypertensive rat (SHR), and Wistar-Kyoto (WKY) rats in a dose-dependent dependent manner. The vasorelaxant activity of HPI is probably due to the presence of amino acids such as arginine, cysteine, and serine. Also, male SD rats showed significantly lower %dilation compared to female SD rats. Whereas male WKY showed significantly higher HPI induced %dilation response compared to female WKY, female SHR, and male SHR. Sex differences observed in normotensive rats are probably due to bioactive components of HPI. Further studies are required to identify the mechanism involved in HPI-induced vasodilation and elucidate the sex difference observed. In summary, we have shown for the first time that HPI is a vasodilator. Our study findings indicate that HPI may be used for improving the vascular function of hypertensive vessels.