Ozone alteration of membrane permeability in Chlorella. I. Permeability of potassium ion as measured by /sup 86/Rubidium tracer
The addition of ozone to a suspension of Chlorella sorokiniana causes a rapid loss of K/sup +/, as measured by efflux of /sup 86/Rb from prelabeled cells. The efflux of the tracer is stimulated some 15 to 20 times over that of the control. For about 100 microliters per liter ozone, about 25 minutes (6 x 10/sup -8/ moles O/sub 3/ delivered per minute) of exposure are required for a 50% depletion of the intracellular K/sup +/. The stimulation of K/sup +/ efflux is nearly linearly dependent upon the amount of ozone delivered into the solution. Following short pulses of ozone (lasting 1 to 5 minutes), efflux rates return to the control level but only after about 15 minutes. While influx of K/sup +/ is ultimately inhibited by ozone, at low concentrations or for short exposure times the tracer influx is stimulated 100 to 200%. Ozone stimulation of an active pump mechanism is unlikely in view of a concomitant decrease in respiration. Thus, this influx may represent movement of K/sup +/ along its electrochemical gradient. Assuming that influx and efflux are in steady-state according to the Goldman equation, it was calculated that the membrane potential for K/sup +/ of -80 to -90 millivolts in control cells drops to -40 millivolts with ozone exposure and is accompanied by a calculated increased permeability to K/sup +/ of 2- to 3-fold. 25 references, 6 figures.
- Research Organization:
- Univ. of California, Riverside
- OSTI ID:
- 5553330
- Journal Information:
- Plant Physiol.; (United States), Vol. 64
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
CELL MEMBRANES
PERMEABILITY
CHLORELLA
OZONE
BIOLOGICAL EFFECTS
DOSE-RESPONSE RELATIONSHIPS
EXCRETION
INHIBITION
POTASSIUM
RUBIDIUM 86
STIMULATION
TRACER TECHNIQUES
UPTAKE
ALGAE
ALKALI METAL ISOTOPES
ALKALI METALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CELL CONSTITUENTS
CLEARANCE
DAYS LIVING RADIOISOTOPES
ELEMENTS
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MEMBRANES
METALS
MICROORGANISMS
MINUTES LIVING RADIOISOTOPES
NUCLEI
ODD-ODD NUCLEI
PLANTS
RADIOISOTOPES
RUBIDIUM ISOTOPES
UNICELLULAR ALGAE
560303* - Chemicals Metabolism & Toxicology- Plants- (-1987)
550501 - Metabolism- Tracer Techniques