Inward rectifier K+ channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain

Voltage‐dependent potassium currents in hypertrophied rat astrocytes after a cortical stab wound

“…Outwardly rectifying K + channels are thought to be involved in cell proliferation and in maintaining “auxiliary” V m under pathological conditions when the cellular membrane is depolarized and K IR channels are nonactive (Chung et al, 1998; Pannicke et al, 2000), and they contribute to V m maintenance after changes in [K + ] e (Chvátal et al, 1997). Similarly to our results, an upregulation of K DR currents in reactive astrocytes was shown in situ (Bordey et al, 2001) and in vitro (MacFarlane and Sontheimer, 1997; Perillan et al, 1999, 2000), as well as their sensitivity to 4‐AP and TEA chloride. In addition to work conducted by other investigators (MacFarlane and Sontheimer, 1997; Bordey et al, 2001), we have shown that the appearance of A2 astrocytes correlates with astrocyte proliferation only at the immediate site of a stab wound.…”

Voltage‐dependent potassium currents in hypertrophied rat astrocytes after a cortical stab wound

“…Outwardly rectifying K + channels are thought to be involved in cell proliferation and in maintaining “auxiliary” V m under pathological conditions when the cellular membrane is depolarized and K IR channels are nonactive (Chung et al, 1998; Pannicke et al, 2000), and they contribute to V m maintenance after changes in [K + ] e (Chvátal et al, 1997). Similarly to our results, an upregulation of K DR currents in reactive astrocytes was shown in situ (Bordey et al, 2001) and in vitro (MacFarlane and Sontheimer, 1997; Perillan et al, 1999, 2000), as well as their sensitivity to 4‐AP and TEA chloride. In addition to work conducted by other investigators (MacFarlane and Sontheimer, 1997; Bordey et al, 2001), we have shown that the appearance of A2 astrocytes correlates with astrocyte proliferation only at the immediate site of a stab wound.…”

Cell Swelling and a Nonselective Cation Channel Regulated by Internal Ca2+and ATP in Native Reactive Astrocytes from Adult Rat Brain

“…2 B, a), consistent with previous observations in primary cultured cells of the same origin (Perillan et al, 1999(Perillan et al, , 2000. Inward currents negative to the K ϩ equilibrium potential (E K ) were usually Ͻ100 pA, much smaller than values reported in cultured neonatal astrocytes (Ransom and Sontheimer, 1995) but consistent with findings in astrocytes freshly isolated from injured brain (Bordey and Sontheimer, 1998;Schroder et al, 1999).…”

“…This finding of relative impermeability to divalent cations is consistent with observations in most other preparations (Rae et al, 1990;Popp and Gogelein, 1992;Ono et al, 1994), although in some (Cook et al, 1990), measurable permeability to Ca 2ϩ was reported. Although the mechanism was not studied in detail, we also found that physiological concentrations of Mg 2ϩ appeared to block the channel from inside (Popp and Gogelein, 1992), resulting in inward rectification similar to that observed in other channels such as Kir2.3 (Chuang et al, 1997;Perillan et al, 2000). Finally, in a separate series of experiments, we measured relative permeabilities of small organic cations and found that fitting of these data to the Renkin equation indicated a relative pore radius of 0.41 nm, similar to the pore size reported for the NC C a-ATP channel in a secretory epithelial cell line (Cook et al, 1990).…”

Immunohistochemical Distribution of Inwardly Rectifying K+ Channels in the Medulla Oblongata of the Rat

“…Furthermore, Kir2.3 has been identified in the astrocytes from adult rat brain [14]. In the present study, glial cells that immunoreactive for Kir1.1, Kir2.3 and Kir4.1 were also immunoreactive for GFAP but not for CNPase.…”

Voltage‐dependent potassium currents in hypertrophied rat astrocytes after a cortical stab wound

“…Outwardly rectifying K + channels are thought to be involved in cell proliferation and in maintaining “auxiliary” V m under pathological conditions when the cellular membrane is depolarized and K IR channels are nonactive (Chung et al, 1998; Pannicke et al, 2000), and they contribute to V m maintenance after changes in [K + ] e (Chvátal et al, 1997). Similarly to our results, an upregulation of K DR currents in reactive astrocytes was shown in situ (Bordey et al, 2001) and in vitro (MacFarlane and Sontheimer, 1997; Perillan et al, 1999, 2000), as well as their sensitivity to 4‐AP and TEA chloride. In addition to work conducted by other investigators (MacFarlane and Sontheimer, 1997; Bordey et al, 2001), we have shown that the appearance of A2 astrocytes correlates with astrocyte proliferation only at the immediate site of a stab wound.…”

Cell Swelling and a Nonselective Cation Channel Regulated by Internal Ca2+and ATP in Native Reactive Astrocytes from Adult Rat Brain

“…2 B, a), consistent with previous observations in primary cultured cells of the same origin (Perillan et al, 1999(Perillan et al, , 2000. Inward currents negative to the K ϩ equilibrium potential (E K ) were usually Ͻ100 pA, much smaller than values reported in cultured neonatal astrocytes (Ransom and Sontheimer, 1995) but consistent with findings in astrocytes freshly isolated from injured brain (Bordey and Sontheimer, 1998;Schroder et al, 1999).…”

“…This finding of relative impermeability to divalent cations is consistent with observations in most other preparations (Rae et al, 1990;Popp and Gogelein, 1992;Ono et al, 1994), although in some (Cook et al, 1990), measurable permeability to Ca 2ϩ was reported. Although the mechanism was not studied in detail, we also found that physiological concentrations of Mg 2ϩ appeared to block the channel from inside (Popp and Gogelein, 1992), resulting in inward rectification similar to that observed in other channels such as Kir2.3 (Chuang et al, 1997;Perillan et al, 2000). Finally, in a separate series of experiments, we measured relative permeabilities of small organic cations and found that fitting of these data to the Renkin equation indicated a relative pore radius of 0.41 nm, similar to the pore size reported for the NC C a-ATP channel in a secretory epithelial cell line (Cook et al, 1990).…”

Immunohistochemical Distribution of Inwardly Rectifying K+ Channels in the Medulla Oblongata of the Rat

“…Furthermore, Kir2.3 has been identified in the astrocytes from adult rat brain [14]. In the present study, glial cells that immunoreactive for Kir1.1, Kir2.3 and Kir4.1 were also immunoreactive for GFAP but not for CNPase.…”

Voltage‐dependent potassium currents in hypertrophied rat astrocytes after a cortical stab wound

“…Outwardly rectifying K + channels are thought to be involved in cell proliferation and in maintaining “auxiliary” V m under pathological conditions when the cellular membrane is depolarized and K IR channels are nonactive (Chung et al, 1998; Pannicke et al, 2000), and they contribute to V m maintenance after changes in [K + ] e (Chvátal et al, 1997). Similarly to our results, an upregulation of K DR currents in reactive astrocytes was shown in situ (Bordey et al, 2001) and in vitro (MacFarlane and Sontheimer, 1997; Perillan et al, 1999, 2000), as well as their sensitivity to 4‐AP and TEA chloride. In addition to work conducted by other investigators (MacFarlane and Sontheimer, 1997; Bordey et al, 2001), we have shown that the appearance of A2 astrocytes correlates with astrocyte proliferation only at the immediate site of a stab wound.…”

Cell Swelling and a Nonselective Cation Channel Regulated by Internal Ca2+and ATP in Native Reactive Astrocytes from Adult Rat Brain

“…2 B, a), consistent with previous observations in primary cultured cells of the same origin (Perillan et al, 1999(Perillan et al, , 2000. Inward currents negative to the K ϩ equilibrium potential (E K ) were usually Ͻ100 pA, much smaller than values reported in cultured neonatal astrocytes (Ransom and Sontheimer, 1995) but consistent with findings in astrocytes freshly isolated from injured brain (Bordey and Sontheimer, 1998;Schroder et al, 1999).…”

“…This finding of relative impermeability to divalent cations is consistent with observations in most other preparations (Rae et al, 1990;Popp and Gogelein, 1992;Ono et al, 1994), although in some (Cook et al, 1990), measurable permeability to Ca 2ϩ was reported. Although the mechanism was not studied in detail, we also found that physiological concentrations of Mg 2ϩ appeared to block the channel from inside (Popp and Gogelein, 1992), resulting in inward rectification similar to that observed in other channels such as Kir2.3 (Chuang et al, 1997;Perillan et al, 2000). Finally, in a separate series of experiments, we measured relative permeabilities of small organic cations and found that fitting of these data to the Renkin equation indicated a relative pore radius of 0.41 nm, similar to the pore size reported for the NC C a-ATP channel in a secretory epithelial cell line (Cook et al, 1990).…”

Immunohistochemical Distribution of Inwardly Rectifying K+ Channels in the Medulla Oblongata of the Rat

“…Furthermore, Kir2.3 has been identified in the astrocytes from adult rat brain [14]. In the present study, glial cells that immunoreactive for Kir1.1, Kir2.3 and Kir4.1 were also immunoreactive for GFAP but not for CNPase.…”