Protein kinase A signalling is involved in the relaxant responses to the selective β-oestrogen receptor agonist diarylpropionitrile in rat aortic smooth muscle in vitro.

Objectives: The oestrogen receptor β (ERβ) selective agonist diarylpropionitrile (DPN) relaxes endothelium-denuded rat aorta, but the signalling mechanism is unknown. The aim of this study was to assess whether protein kinase A (PKA) signalling is involved in DPN action.

Methods: cAMP was measured by radioimmunoassay, HSP20 phosphorylation by 2D gel electrophoresis with immunoblotting, and membrane potential and free cytosolic calcium by flow cytometry.

Endothelium-independent vasorelaxation by the selective alpha estrogen receptor agonist propyl pyrazole triol in rat aortic smooth muscle.

Objectives: This study investigated the signalling mechanism of the relaxant responses to the estrogen receptor (ERalpha) agonist PPT (propyl pyrazole triol) in endothelium-denuded rat aortic rings.

Methods: Several compounds, including protein kinase G (PKG) inhibitors and potassium channel inhibitors, were tested against PPT-dependent rat aortic relaxation. Cyclic GMP and cytosolic calcium responses to PPT in isolated aortic smooth muscle were investigated in parallel.

Role of chloride transport proteins in the vasorelaxant action of nitroprusside in isolated rat aorta.

Chloride ions play a key role in smooth muscle contraction, but little is known concerning their role in smooth muscle relaxation. Here we investigated the effect of chloride transport inhibitors on the vasorelaxant responses to nitroprusside in isolated and endothelium-denuded rat aorta, precontracted with phenylephrine 1 muM. Incubation of aortic rings in NO(3)(-) media strongly potentiated the vasorelaxant responses to nitroprusside.

Cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel and Na-K-Cl cotransporter NKCC1 isoform mediate the vasorelaxant action of genistein in isolated rat aorta.

The soy phytoestrogen genistein is a potent vasorelaxant, but its mechanism of action is poorly understood. Here, we used endothelium-denuded rat aorta to investigate the role of the cyclic AMP(cAMP)-activated, cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, and its associated Na-K-Cl cotransporter NKCC1. Isolated, endothelium-denuded rat aorta was contracted with phenylephrine 1 microM, and the vasorelaxant responses to genistein were investigated under conditions where CFTR was inhibited by DPC (diphenylamine-2-carboxylic acid) or glibenclamide (n=6 for compound).

Isoosmotic shrinkage by self-stimulated outward Na-K-Cl cotransport in quail erythrocytes.

In mammalian erythrocytes, outward fluxes by the Na-K-Cl cotransporter NKCC have been clearly characterized, but NKCC fluxes are small and their physiological role, if any, is poorly understood. Avian erythrocytes are nucleated cells, in which a physiologically relevant NKCC acts as a cell volume regulator. Therefore, we further investigated outward cotransport and its relation to cell volume by using quail erythrocytes.

Soy milk lowers blood pressure in men and women with mild to moderate essential hypertension.

Soy-based diets reduce blood pressure in spontaneously hypertensive rats, but apparently not in hypertensive humans. In the present study, the antihypertensive potential of soy milk (500 mL twice daily) compared with cow's milk was investigated in a 3-mo double-blind randomized study of 40 men and women with mild-to-moderate hypertension. Before initiation of the study, urinary isoflavonoids (measured by HPLC) were undetectable in most cases (for genistein, they were always <100 micromol/L).