• The Korean Journal of Pharmacology
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• v.30 no.2
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• pp.153-165
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• 1994

In this study, we tested the influences of several ${\kappa}$ opioid ligands on the $[^3H]diprenorphine$ binding in rat and guinea pig cortex membrane preparations. Using paradigm to block ${\mu}\;and\;{\delta}$ opioid receptors with $DAMGO(1{\mu}M)$ and $DPDPE(1{\mu}M)$, $[^3H]diprenorphine$ labeled ${\kappa}$ sites. Competition analysis in both rat and guinea pig cortex has shown a single population of $[^3H]diprenorphine$ binding site with different Kd values, respectively. There is a significant difference in Ki values of (-) WIN44441 and (+)WIN44441 in both rat and guinea pig cortex. Bremazocine, (-)ethylketocyclazocine, (-)cyclazocine, nor-binaltorphimine effectively inhibited the $[^3H]diprenorphine$ binding with different Ki values in rat and guinea pig cortex. U-69,593, U-50,488H and dynorphine-A (1-8) did not inhibit the $[^3H]diprenorphine$ binding in rat but in guinea pig cortex. Nor-binaltorphimine was a ligand discriminate the ${\kappa}_1$, and ${\kappa}_2$ receptor most effectively. We, also, examined the influence of Na ion and $GTP{\gamma}S$, a nonhydrolyzable guanine nucleotide analog, on the inhibition of $[^3H]diprenorphine$ binding by diprenorphine, (-)ethyl-ketocyclazocine, U-69,593 and bremazocine. By the replacement of NaCl with N-methy-D-glucamine or addition of $GTP{\gamma}S$, Ki values of diprenorpnine were not changed and that of ethylketocyclazocine were changed significantly in both rat and guinea pig cortex. The Ki value of bremazocine was decreased by removal of Na ion, and increased by $GTP{\gamma}S$, however, was not changed by any one of either. These results suggest that there are 2 kinds of subtypes of ${\kappa}$ opioid receptor, ${\kappa}_1$, and ${\kappa}_2$, showing different Ki values for various ${\kappa}$ opioid ligands, also, bremazocine possess the antagonistic property at ${\kappa}_2$ site which is dominant subtype of K receptor in rat cortex.

• Journal of Embryo Transfer
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• v.19 no.2
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• pp.101-112
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• 2004

Chloride($Cl^-$) channels play critical roles in cell homeostasis and its specific functions such as volume regulation, differentiation, secretion, and membrane stabilization. The presence of these channels have been reported in all kinds of cells and even in frog oocytes. These essential role of $Cl^-$­ channels in cell homeostasis possibly play any role in egg homeostasis and in the early stage of development, however, there has been no report about the presence of $Cl^-$­ channel in the mammalian oocyte. This study was performed to elucidate the presence of $Cl^-$­ channels in hamster eggs. When allowing only $Cl^-$­ to pass through the channel of the egg membrane by using impermeant cation such as N-methyl-D-glucamine(NMDG), single channel currents were recorded. These channel currents showed typical long-lasted openings interrupted by rapid flickering. Mean open $time({\tau}o)$ was 43${\pm}$10.14 ms(n=9, at 50 mV). The open probability(Po) was decrease with depolarization. The current-voltage relation showed outward rectification. Outward slop conductance(32${\pm}$5.4 pS, n=22) was steeper than the inward slop conductance(10${\pm}$1.3 pS). Under the condition of symmetrical 140 mM NaCl, single channel currents were reversed at 0 mV(n=4). This reversal potential(Erev) was shifted from 0 mV at 140 mM concentration of internal NaCl(140 mM [Na+]i) to ­9.8${\pm}$0.5 mV(n=4) at 70 mM [Na+]i and 11.5${\pm}$1.9 mV at 280 mM [Na+]i(n=4) respectively, strongly suggesting that these are single $Cl^-$­ channel currents. To examine further whether this channel has pharmacological property of the $Cl^-$­ channel, specific Cl­ channel blockers, IAA-94(Indanyloxyacetic acid-94) and DIDS(4, 4'-diisothiocyan ostillben- 2-2'disulfonic acid) were applied. IAA-94 inhibited the channel current in a dose-dependent manner and revealed a rapid and flickering block. From these electrophysiological and pharmacological resluts, we found the novel $Cl^-$­ channel present in the hamster oocyte membrane. The first identification of $Cl^-$­ channel in the hamster oocyte may give a clue for the further study on the function of $Cl^-$­ channel in the fertilization and cell differentiation.