Asphyxia and diuretic-induced changes in the Ca2+ concentration of endolymph

Atsuko Takamaki, Yoshiaki Mori, Michitoshi Araki, Akihito Mineharu, Yoshiro Sohma, Junko Tashiro, Ryotaro Yoshida, Hiroshi Takenaka, Takahiro Kubota

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)35-44
Number of pages10
JournalJapanese Journal of Physiology
Issue number1
Publication statusPublished - 2003 Feb
Externally publishedYes


  • Asphyxia
  • Ca concentration
  • Ca-selective microelectrode
  • Cochlear endolymph
  • Diuretics

ASJC Scopus subject areas

  • Physiology


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