EFFECT OF ELASTIN PEPTIDES ON VASCULAR TONE

Elastin peptides are present in human blood. As elastin receptors exis t on several cell types, especially endothelial cells, this investigat ion was carried out to study the effect of elastin peptides on vascula r tone. For this purpose, rat aortic rings were mounted in an organ ba th for isometric tension measurements. Elastin peptides (kappa-elastin ) were added in the concentration range of 0.1 ng/ml to 1 mu g/ml, con centrations similar to those found in the circulating blood. In rat ao rtic rings, precontracted or not with noradrenaline (10(-6) M), elasti n peptides induced an endothelium-dependent vasodilation. The pretreat ment of aortic rings with N-omega-nitro-L-arginine methyl ester (10(-5 ) M), an inhibitor of nitric oxide (NO) production, or with indomethac in (10(-5) M), an inhibitor of cyclooxygenase, prevented elastin pepti de-induced vasodilation. These findings suggest that elastin peptides act through the synthesis of prostanoids, leading to the production of NO. Moreover, this relaxant effect of elastin peptides was decreased or inhibited when aortic rings were treated with lactose (10(-5) to 10 (-2) M) or laminin (10(-6) to 10(-4) mg/ml) whereas lactose or laminin was unable to inhibit acetylcholine-induced vasodilation. These findi ngs suggest that the inhibitory effects of lactose and laminin are spe cific for elastin peptide receptors and are in agreement with previous studies on these receptors. As there is evidence of the degradation o f elastin in several vascular diseases, the concept that elastin pepti des may contribute to the control of vascular tone is discussed.