Effect of the CYP3A inhibitor ketoconazole on the PXR-mediated induction of CYP3A activity.

Purpose: The aim of this clinical study was to investigate a previously proposed mechanism of ketoconazole-mediated inhibition of cytochrome P450 3A (CYP3A) induction.

Methods: A two-phase, randomized, cross-over, open, mono-centre trial was carried out. Participants received ketoconazole and St John's wort for 8 days to study the proposed suppression of St John's wort-mediated induction of CYP3A at the transcriptional level.

Rice K+ uptake channel OsAKT1 is sensitive to salt stress.

Potassium ions constitute the most important macronutrients taken up by plants. To unravel the mechanisms of K+ uptake and its sensitivity to salt stress in the model plant rice, we isolated and functionally characterized OsAKT1, a potassium channel homologous to the Arabidopsis root inward rectifier AKT1. OsAKT1 transcripts were predominantly found in the coleoptile and in the roots of young rice seedlings.

The K+ channel KZM1 mediates potassium uptake into the phloem and guard cells of the C4 grass Zea mays.

In search of K(+) channel genes expressed in the leaf of the C(4) plant Zea mays, we isolated the cDNA of KZM1 (for K(+) channel Zea mays 1). KZM1 showed highest similarity to the Arabidopsis K(+) channels KAT1 and KAT2, which are localized in guard cells and phloem. When expressed in Xenopus oocytes, KZM1 exhibited the characteristic features of an inward-rectifying, potassium-selective channel.