PT  - JOURNAL ARTICLE
AU  - Katsuhara, Maki
AU  - Kuchitsu, Kazuyuki
AU  - Takeshige, Kazuhiko
AU  - Tazawa, Masashi
TI  - Salt Stress-Induced Cytoplasmic Acidification and Vacuolar Alkalization in <em>Nitellopsis obtusa</em> Cells
AID  - 10.1104/pp.90.3.1102
DP  - 1989 Jul 01
TA  - Plant Physiology
PG  - 1102--1107
VI  - 90
IP  - 3
4099  - http://www.plantphysiol.org/content/90/3/1102.short
4100  - http://www.plantphysiol.org/content/90/3/1102.full
SO  - Plant Physiol.1989 Jul 01; 90
AB  - Time courses of cytoplasmic and vacuolar pH changes under salt stress were monitored by in vivo31P-nuclear magnetic resonance spectroscopy in intact cells of Nitellopsis obtusa. When cells were treated with 100 millimolar NaCl for 2 hours, the cytoplasmic pH deceased from 7.2 to 7.0, while the vacuolar pH increased from 4.9 to 5.2. This salt-induced breakdown of the pH gradient between the cytoplasm and the vacuole was also confirmed through direct measurements of change in vacuolar pH with a micro-pH electrode. We speculate that the intracellular pH changes induced by the salt stress mainly results from the inhibition of the H+-translocating pyrophosphatase in the vacuolar membrane, since this H+-translocating system is sensitive to salt-induced increase in the cytoplasmic [Na+] and a simultaneous decrease in the cytoplasmic [K+]. Since disturbance of the cytoplasmic pH value should have serious consequences on the homeostasis of living cells, we propose that the salt-induced intracellular pH changes are one of initial and important steps that lead to cell death.