Vol.

175,

March

No.

2, 1991

BIOCHEMICAL

AND

BIOPHYSICAL

RESEARCH

COMMUNICATIONS Pages

15, 1991

611-616

QUANTIFICATION OF INTRACELLULAR FREE SODIUM IONS BY USING NEW FLUORESCENT INDICATOR, SODIUM-BINDING BENZOFURAN ISOPHTHALATE IN GUINEA PIG MYOCYTES

A

Hiroshi Satoh, Hideharu Hayashi, Naohisa Nodas Hajime Terada, Akira Kobayashi, Yutaka Yamashita Tohru KawaiH, Masahiko Hiranoff and Noboru Yamazaki The Third Medical

of

Department of Internal Medicine, *The Department Photonics, Hamamatsu University School of Medicine, 3600, Handa-Cho, Hamamatsu, 431-31 Japan

#Hamamatsu

Received

Photonics

February

K.K., 434

5000, Japan

Hirakuchi,

Hamakita,

1, 1991

Isolated guinea myocytes were loaded with the Na+pig sensitive fluorescent probe, sodium-binding benzofuran isophthalate (SUPI). The 3401380 nm fluorescence ratios were measured with fluorescence microscopy. The distribution of intracellular Na+ concentration ([Na+]i) was homogenous, and the resting [Na+]i was 8.4 2 0.5 mM. There was a significant mean relationship (r=0.66, p