Blood pressure-lowering and vascular modulator effects of Acorus calamus extract are mediated through multiple pathways.

This investigation was aimed to provide a pharmacologic basis to the medicinal use of Acorus calamus in cardiovascular disorders. In normotensive anesthetized rats, crude extract of Acorus calamus and its ethylacetate and nHexane fractions caused a fall in mean arterial pressure. In rabbit aorta rings, crude extract was more potent against high K (80 mM), ethylacetate against phenylephrine (1 microM), whereas nHexane fraction was equipotent against both precontractions. Crude extract exhibited a vasoconstrictor effect on baseline. Pretreatment of aortic rings with crude extract and its fractions shifted Ca concentration-response curves to the right, similar to verapamil. Crude extract and ethylacetate fraction suppressed phenylephrine peak formation in Ca-free medium. In rat aorta preparations, crude extract exhibited endothelium-independent relaxation with a vasodilatory effect against high K. nHexane fraction caused an endothelium-dependent Nomega-nitro-l-arginine methyl ester-sensitive vasorelaxant along with ryanodine-sensitive vasoconstrictor effect on baseline tension and partially inhibited high K, although ethylacetate fraction caused an endothelium-independent relaxant and endothelium-dependent vasoconstrictor effect. These data indicate that crude extract possesses a combination of effects, relaxant effects mediated possibly through Ca antagonism in addition to a nitric oxide pathway, although the associated vasoconstrictor effects may be meant by nature to offset excessive vasodilatation, thus providing a pharmacologic rationale to its cardiovascular medi-cinal uses.

Developmental anatomy of the root cortex of the basal monocotyledon, Acorus calamus (Acorales, Acoraceae).

BACKGROUND AND AIMS: The anatomical structure and development of adventitious roots were analysed in the basal monocotyledon, Acorus calamus, to determine to what extent those features are related to phylogenetic position. METHODS: Root specimens were harvested and sectioned, either with a hand microtome or freehand, at varying distances from the root tip and examined under the microscope using a variety of staining techniques. KEY RESULTS: Roots of Acorus calamus possess a unique set of developmental characteristics that produce some traits similar to those of another basal angiosperm group, Nymphaeales. The root apical meristem organization seems to be intermediate between that of a closed and an open monocotyledonous root apical meristem organization. The open-type root apical meristem consists of a curved zone of cortical initials and epidermal initials overlying the vascular cylinder initials; the epidermal part of the meristem varies in its association with the cortical initials and columellar initials of the promeristem. The cortex develops an endodermis with only Casparian bands, a dimorphic exodermis with Casparian bands and suberin lamellae, and a polygonal aerenchyma by differential expansion, as also observed in the Nymphaeales and some dicotyledonous species. The stele has characteristics like those of members of the Nymphaeaceae. CONCLUSIONS: Specific anatomical and developmental attributes of Acorus roots seem to be related to the phylogenetic position of this genus.