EFFECTS OF DIETARY SPIRULINA-MAXIMA ON ENDOTHELIUM-DEPENDENT VASOMOTOR RESPONSES OF RAT AORTIC RINGS

The aim of this study was to evaluate the effects of Spirulina maxima on vasomotor responses of aorta rings from male Wistar rats fed on a p urified diet. For this purpose, the animals (weighing 200-240 g) were allocated randomly in two groups. One receiving purified control diet (A) and the other receiving purified diet containing 5% Spirulina (B). Purified diets were according to American Institute of Nutrition guid elines and adjusted to Spirulina protein content. All animals were fed (20 g/day/rat) during two weeks, receiving water ad libitum and 12 h. light-dark cycles. Spirulina mat ima effects were evaluated by concen tration-response (CR) curves of aorta rings with or without endotheliu m to phenylephrine (PE), both in presence and absence of indomethacin (Indom) or indomethacin plus L-NAME (Indom. + L-NAME), and to carbacho l (CCh). Aorta rings with endothelium from group B showed, relative to corresponding rings from group A: 1) a significant decrease in the ma ximal tension developed in response to PE. 2) this decrease was revert ed by Indom. 3) Indom. + L-NAME induced an additional increase in the contractile responses to PE. 4) a significant shift to the left of the CR curve to CCh. No significant differences were observed in the tens ion developed in response to PE in rings without endothelium from eith er group. These results suggest that Spirulina maxima may decrease vas cular tone by increasing the synthesis and release of both a vasodilat ing cyclooxygenase-dependent product of arachidonic acid and nitric ox ide, as well as by decreasing the synthesis and release of st vasocons tricting eicosanoid from the endothelial cells. (C) 1997 Elsevier Scie nce Inc.