Characterization of oscillations in cytosolic free Ca2+ concentration and measurement of cytosolic Na+ concentration changes evoked by angiotensin II and vasopressin in individual rat aortic smooth muscle cells. Use of microfluorometry and digital imaging

Johnson, E.; Théler, Jean-Marc; Capponi, Alessandro M.; Vallotton, Michel B.

doi:10.1016/s0021-9258(18)98944-1

Cited by 48 publications

(1 citation statement)

References 54 publications

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“…Moreover, a K ϩ current present in human neuroblastoma cells, which shares many properties with eag cur-rents (Meyer and Heinemann, 1998), had previously been shown to be blocked by intracellular Na ϩ (Johansson et al, 1996). The intracellular Na ϩ concentration changes in response to many cellular events, usually related to the activation of either Na ϩ /Ca 2 ϩ or Na ϩ /H ϩ antiporters (see for example Harootunian et al, 1989;Borin and Siffert, 1991;Johnson et al, 1991). In this paper, we show that Na ϩ is able to block the r-eag channel only after MPF activation in oocytes, implying profound modifications in the ionconduction pathway during cell cycle-related processes.…”

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Cell Cycle–related Changes in the Conducting Properties of r-eag K+ Channels

Pardo

Brüggemann

Camacho

et al. 1998

The Journal of Cell Biology

109

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Release from arrest in G2 phase of the cell cycle causes profound changes in rat ether-à-go-go (r-eag) K+ channels heterologously expressed in Xenopus oocytes. The most evident consequence of the onset of maturation is the appearance of rectification in the r-eag current. The trigger for these changes is located downstream of the activation of mitosis-promoting factor (MPF). We demonstrate here that the rectification is due to a voltage-dependent block by intracellular Na+ ions. Manipulation of the intracellular Na+ concentration indicates that the site of Na+ block is located ∼45% into the electrical distance of the pore and is only present in oocytes undergoing maturation. Since the currents through excised patches from immature oocytes exhibited a fast rundown, we studied CHO-K1 cells permanently transfected with r-eag. These cells displayed currents with a variable degree of block by Na+ and variable permeability to Cs+. Partial synchronization of the cultures in G0/G1 or M phases of the cell cycle greatly reduced the variability. The combined data obtained from mammalian cells and oocytes strongly suggest that the permeability properties of r-eag K+ channels are modulated during cell cycle–related processes.

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confidence: 99%