TY - JOUR
T1 - Asphyxia and diuretic-induced changes in the Ca2+ concentration of endolymph
AU - Takamaki, Atsuko
AU - Mori, Yoshiaki
AU - Araki, Michitoshi
AU - Mineharu, Akihito
AU - Sohma, Yoshiro
AU - Tashiro, Junko
AU - Yoshida, Ryotaro
AU - Takenaka, Hiroshi
AU - Kubota, Takahiro
PY - 2003/2
Y1 - 2003/2
N2 - Using Ca2+-selective microelectrodes based on the neutral carrier, ETH-1001 with polyvinyl chloride (PVC), we have measured changes in the free Ca2+ concentration of guinea pig cochlear endolymph ([Ca]e) after transient asphyxia or intravenous administration of diuretics. Under the control conditions, the endocochlear potential (EP) was +80 mV, and the [Ca]e was in the range 1.4×10-7-2.4×10-6 M (n=16). Transient asphyxia (1-1.5 min) produced an increase in the [Ca]e with a fall in the EP, whereas the cessation of the asphyxia led to a quick recovery of both [Ca]e and EP to their control levels. Intravenous administration of furosemide (60 mg/kg) or bumetanide (30mg/kg) also caused an increase in the [Ca]e with a fall in the EP, followed by a gradual recovery of both [Ca]e and EP. From these results, we obtained a significant correlation between EP and p[Ca]e (= -log[Ca]e), and conclude that (1) the [Ca]e is extremely low, around 10-6 M or less, under normal conditions and (2) the [Ca]e is directly correlated with EP under physiological conditions.
AB - Using Ca2+-selective microelectrodes based on the neutral carrier, ETH-1001 with polyvinyl chloride (PVC), we have measured changes in the free Ca2+ concentration of guinea pig cochlear endolymph ([Ca]e) after transient asphyxia or intravenous administration of diuretics. Under the control conditions, the endocochlear potential (EP) was +80 mV, and the [Ca]e was in the range 1.4×10-7-2.4×10-6 M (n=16). Transient asphyxia (1-1.5 min) produced an increase in the [Ca]e with a fall in the EP, whereas the cessation of the asphyxia led to a quick recovery of both [Ca]e and EP to their control levels. Intravenous administration of furosemide (60 mg/kg) or bumetanide (30mg/kg) also caused an increase in the [Ca]e with a fall in the EP, followed by a gradual recovery of both [Ca]e and EP. From these results, we obtained a significant correlation between EP and p[Ca]e (= -log[Ca]e), and conclude that (1) the [Ca]e is extremely low, around 10-6 M or less, under normal conditions and (2) the [Ca]e is directly correlated with EP under physiological conditions.
KW - Asphyxia
KW - Ca concentration
KW - Ca-selective microelectrode
KW - Cochlear endolymph
KW - Diuretics
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U2 - 10.2170/jjphysiol.53.35
DO - 10.2170/jjphysiol.53.35
M3 - Article
C2 - 12689356
AN - SCOPUS:0037322145
SN - 0021-521X
VL - 53
SP - 35
EP - 44
JO - Japanese Journal of Physiology
JF - Japanese Journal of Physiology
IS - 1
ER -