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Abstract

The relationship between the calcium concentration and the isometric tension obtained with different techniques of skinning provides information on the biochemical events of contraction in vascular smooth muscle. Muscle preparations of the rabbit femoral artery were skinned with triton X-100, saponin, beta-escin and alpha-toxin and the relationship between the calcium concentration and isometric tension was determined at different preparation lengths. We determined the calcium sensitivity as a function of muscle length with different techniques of skinning. At a pCa of 6.0, triton X-100 skinned smooth muscle of the femoral artery generated 50% of the maximal tension. In alpha-toxin skinned preparations, this calcium sensitivity was shifted to a pCa of 5.6. The sensitivity of the saponin and 3-escin skinned preparations were in between those of the triton X-100 and the alpha-toxin skinned preparations. The cooperativity of the regulation of contraction varied among the differently skinned preparations between 3 (alpha-toxin) and 6 (triton X-100). The relationships between the calcium concentration and the isometric tension of the differently skinned preparations up to the optimal length for tension generation did not exhibit any length dependency. The length tension relationship, obtained from the maximal response at the highest calcium concentration is in line with that from other studies. The presence of intracellular proteins and membranes affects the regulation of contraction in smooth muscle of the femoral artery.

Mechanisms of lower extremity vein dysfunction in chronic venous disease and implications in management of varicose veins

“…Escin exerts its venotonic action through several mechanisms including improved permeability of endothelial cells, release of endothelium-derived vasoconstrictors such as prostaglandin-F2α, and vein sensitization to the contractile actions of histamine and serotonin [157,162,163] . Escin is also known to form small pores in the cell plasma membrane and is utilized experimentally to examine the sensitivity of the vascular contraction pathways to various vasoconstrictor agonists, and for permeabilization or skinning of VSMC membrane in order to change critical intracellular ions or regulatory proteins [157,[163][164][165] . Escin-induced pores permit Ca 2+ and other biologically-relevant factors (> 3000 dalton) including calmodulin and heparin to diffuse across the plasma membrane without damaging membrane receptors or coupling mechanisms [166] .…”

“…On the other hand, diosmin may increase lymph drainage, decrease vein inflammation, and inhibit venous cathecol-O-methyltransferase (COMT) and in turn decrease norepinephrine metabolism and prolong its effects on vein constriction [167,168] . Some studies also suggest that diosmin may enhance the venotonic effects of escin [164] . Our recent studies have examined the effects of escin and diosmin in rat IVC [169] .…”

Rho-kinase inhibition attenuates calcium-induced contraction in β-escin but not Triton X-100 permeabilized rabbit femoral artery

“…Three detergents and one pore-forming molecule are generally used to chemically permeabilize smooth muscle tissue (Van Heijst, Blange et al 2000). Saponin forms a complex with cholesterol in membrane leaflets to form ~9 nm pores (Bangham, Horne et al 1962) and uncouples receptors involved in physiological activation of smooth muscle (Itoh, Kuriyama et al 1983).…”