RESUMO
Dependence of the superconducting transition temperature (T(c)) and critial superconducting pressure (P(c)) of the pressure-induced superconductor ß-(BDA-TTP)(2)I(3) [BDA-TTP = 2,5-bis(1,3-dithian-2-ylidene)-1,3,4,6-tetrathiapentalene] on the orientation of uniaxial strain has been investigated. On the basis of the overlap between the upper and lower bands in the energy dispersion curve, the pressure orientation is thought to change the half-filled band to the quarter-filled one. The observed variations in T(c) and P(c) are explained by considering the degree of application of the pressure and the degree of contribution of the effective electronic correlation at uniaxial strains with different orientations parallel to the conducting donor layer.
RESUMO
Carpronium chloride, a hair growth reagent, is known to have a vasodilatory action, but its direct effect on the microcirculation has been known very primitively. This study was aimed to examine its effects on the vascular smooth muscles and blood flow in rat mesenteric arterioles using intravital videomicroscopy. After topically applying carpronium chloride on the microvasculature, we measured changes of diameter and blood flow in the arterioles. During its topical application, arteriolar vasodilation and flow increase were observed, while no change occurred in the mean systemic blood pressure. Our in vivo studies indicated that carpronium chloride achieved dilatation of vascular smooth muscle in the microcirculation.
Assuntos
Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Microcirculação/efeitos dos fármacos , Circulação Esplâncnica/efeitos dos fármacos , Ácido gama-Aminobutírico/análogos & derivados , Animais , Arteríolas/efeitos dos fármacos , Arteríolas/fisiologia , Pressão Sanguínea/efeitos dos fármacos , Feminino , Masculino , Microcirculação/fisiologia , Microscopia de Vídeo , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/fisiologia , Ratos , Ratos Wistar , Circulação Esplâncnica/fisiologia , Vasodilatação/efeitos dos fármacos , Ácido gama-Aminobutírico/farmacologiaRESUMO
A methanolic extract from the leaves of Piper nigrum L. showed a significant stimulatory effect on melanogenesis in cultured murine B16 melanoma cells. Activity-guided fractionation of the methanolic extract led to the isolation of two known lignans, (-)-cubebin (1) and (-)-3,4-dimethoxy-3,4-desmethylenedioxycubebin (2), together with a new lignan, (-)-3-desmethoxycubebinin (3). Among these lignans, 1 and 2 showed a significant stimulatory activity of melanogenesis without any significant effects on cell proliferation.
