. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 020-, 0 18- 0 16- 0 14- 0 12- 0 10- *§. 008- 006- 004- 002- Ci38 - Na-Fcee MB - 10 MM Zinc - 1 mM Zinc 1 mM Histidme + 1 mM Zinc mV mV. 10 MM 100 MM 1 mM Zinc Concentration 10 MM 100 (iM I mM Zinc Concentration Figure 1. (Al Depolarising voltage steps from —40 mV to +60 mV in 20 mV increments (inset) elicit hemichannel currents in a Xenopus oocyte expressing Cx35. With the cell bullied in a sodium-free modified Earth's (MB) solution, in which most of the sodium is replaced by choline (Na+ reduced to +20 mV. The "N
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 020-, 0 18- 0 16- 0 14- 0 12- 0 10- *§. 008- 006- 004- 002- Ci38 - Na-Fcee MB - 10 MM Zinc - 1 mM Zinc 1 mM Histidme + 1 mM Zinc mV mV. 10 MM 100 MM 1 mM Zinc Concentration 10 MM 100 (iM I mM Zinc Concentration Figure 1. (Al Depolarising voltage steps from —40 mV to +60 mV in 20 mV increments (inset) elicit hemichannel currents in a Xenopus oocyte expressing Cx35. With the cell bullied in a sodium-free modified Earth's (MB) solution, in which most of the sodium is replaced by choline (Na+ reduced to +20 mV. The "Na-free" MB solution contained I in mM] C,,HI4NOCI (881, KCI [I], NaHCO, [ N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) [15], Ca(NO,), ], CaCl2 ], and MgSOj []: 10 mg/l gentamvcin was added, and the solution titrated with NaOH to pH (Bl With the addition of 10 juM .-/HC" chloride, the hemichannel currents are greatly enhanced. (C) Increasing the zinc concentration to I mM suppresses the hemichannel currents to levels below those obtained in MB. (D) The effects of zinc concentration on the current-voltage relation (corrected for leakage currents) obtained for an oocyte expressing Cx35. (E) The l-V relation for the endogenous cimnexin (Cx38) displays a similar response to zinc: , a large enhancement of hemicurrents in III juM zinc and suppression in I mM :inc. With the addition of I mM histidine, a zinc chelator, the suppressive effect of I mM zinc is reversed. (F-G) Bar graphs show averaged Jala obtained with Cx35 and C.\38 at different concentrations of zinc. In each data set, the currents recorded in response to a voltage step from the holding potential (—40 mV) to +40 mV have been normalized to the value obtained initially in Na-free MB. Error bars =• ±SEM (n = i for Cx35; with Cx3S, n = 6 for I fjM ZH, and n = 12 for the higher concentrations). to an i i , -merit of hemichannel currents, whereas the low attinity SH
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
