No abstract

Both voltage-activated potassium channels and the concentration of free intracellular calcium have been implicated in the activation of T lymphocytes. Using the patch-clamp technique, we now show an unexpected relationship between the level of intracellular calcium [Ca]i in human lymphocytes and the amplitude of a voltage-dependent current: the elevation of [Ca]i decreases the potassium conductance. This is in contrast to other systems where [Ca]i activates K+ channels. Our results suggest that the level of intracellular calcium regulates the effective number of K+ channels capable of being activated.

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In December 2003 a new 10 kHz multiposition Thomson scattering diagnostic with high spatial resolution has become operational on the TEXTOR tokamak. The system is the follow up of the high-resolution double-pulse Thomson scattering diagnostic. The conventional ruby laser has been replaced by a 10 kHz intracavity laser system and the spectrometer detector has been upgraded with two ultrafast complementary metal-oxide-semiconductor cameras combined with a special image intensifier stage. In the initial phase of operation, a burst of 18 pulses decaying from 17 to 8 J, with a repetition rate of 5 kHz, could be extracted from the laser. At a laser energy up to 12 J per pulse, ten electron temperature and density profiles were measured with an observational error of 10% on the electron temperature ͑T e ͒ and 5% on the electron density ͑n e ͒ at n e = 2.5ϫ 10 19 m −3 per spatial element of 12 mm. The resolution of the detection optics enables to sample either the full plasma diameter of 900 mm with 120 spatial channels of 7.5 mm each, or a 160 mm long edge chord with 98 spatial channels of 1.7 mm each.