Aim: To examine the involvement of K + channels and endothelium in the vascular effects of magnesium lithospermate B (MLB), a hydrophilic active component of Salviae miltiorrhiza Radix. Methods: Isolated rat mesenteric artery rings were employed to investigate the effects of MLB on KCl-or norepinephrine-induced contractions. Conventional whole-cell patch-clamp technique was used to study the effects of MLB on K + currents in single isolated mesenteric artery myocytes. Results: MLB produced a concentration-dependent relaxation in mesenteric artery rings precontracted by norepinephrine (1 μmol/L) with an EC 50 of 111.3 μmol/L. MLB-induced relaxation was reduced in denuded artery rings with an EC 50 of 224.4 μmol/L. MLB caused contractions in KCl-precontracted artery rings in the presence of N-nitro-L-arginine methyl ester (L-NAME) with a maximal value of 130.3%. The vasodilatory effect of MLB was inhibited by tetraethylammonium (TEA) in both intact and denuded artery rings. In single smooth muscle cells, MLB activated BK Ca currents (EC 50 156.3 μmol/L) but inhibited K V currents (IC 50 26.1 μmol/L) in a voltageand concentration-dependent manner. Conclusion: MLB dilated arteries by activating BK Ca channels in smooth muscle cells and increasing NO release from endothelium, but it also contracted arteries precontracted with KCl in the presence of L-NAME.
The operating conditions of measuring
the equilibrium solubility
of 4-hydroxybenzaldehyde in supercritical carbon dioxide (SCCO2) were chosen at temperatures of (308, 318, and 328) K and
five pressure points from (11.0 to 21.0) MPa, while the solubility
data in SCCO2 with three different cosolvents (ethanol,
ethyl acetate, and acetone) at 0.04 (mol·mol–1) were obtained at 318 K and the aforementioned pressure. The solubility
of 4-hydroxybenzaldehyde revealed that the presence of cosolvents
could greatly improve the dissolving ability of solvent. The solubilities
of solutes with five kinds of functional groups substituted for the
formyl group (−CHO) of 4-hydroxybenzaldehyde have been investigated
on the aspects of melting point and intermolecular force. The data
of 4-hydroxybenzaldehyde in pure SCCO2 were successfully
correlated with three semiempirical models (Chrastil, Méndez-Santiago,
and Teja (M-S-T) and Bartle models) for a deviation of (6.82 to 8.50)
%, while the data with cosolvents were calculated by three different
models (modified Chrastil, modified M-S-T, and Sovova models) for
a deviation of (2.98 to 8.87) %. The thermodynamic properties of 4-hydroxybenzaldehyde
were investigated.
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