ACCUMULATION OF RUBIDIUM-86 BY THE RABBIT LENS
In rabbit lenses incubated in vitro in potassium-free Tyrode's solution, accumulation of Rb/sup 86/ remained linear for the initial 4 to 6 hr and in the K- free medium, a T/M (tissue/medium) ratio averaging 18 was found at 4 hr. In Tyrode's solution containing 3 meq K/sup +//I, the T/M ratio averaged 12 at 4 hr. Lenses from different animals varied in T/M ratio from 9 to 30 in a K/sup +/-free medium, but the lenses of the two eyes from the same animal accumulated Rb/sup 86/ at remarkably similar rates. A marked decrease (40%) in accumulation was noted when the medium was glucose-free. This was more marked when the medium was glucose- and K-free than when K was present. Galactose could replace glucose in the medium and restore normal T/M ratios. Accumulation of Rb/sup 86/ was not altered by the absence of oxygen, provided glucose was present, In a Ca- and K- free medium, the accumulation was reduced to less than 20% of the Ca-containing control. Variations of pH between 8.5 and 8.0 failed to alter accumulation of Rb/ sup 86/ but below 8.5 and above 8.0 it was decreased. Accumulation in K-free medium was not influenced by the addition of pitressin, insulin, glycine, deoxycorticosterone, acetazolamide, L-alanine, Na, lactate, choline, or Na ascorbate, The data of accumulation at various Rb concentrations could be fit approximately to a Lineweaver-Burk type plot. The apparent Michaelis-Menten constant, K/sub m/ (half-saturation concentration) approximated 2.3 mM Rb/sup +/, and the max velocity was estimated at 42 mmole/kg lens water per 4 hr. At K concentrations of 4.5 mM the accumulation of trace amounts of Rb/sup 86/ was reduced by 50%. Similar studies with NH/sub 4/ ion in a K-free medium suggested that NH/sub 4/ concentrations of approximates 12 mM irhibited the uptake of Rb/ sup 86/ by 50%. Various metabolic and other inhibitors decreased the capacity of the lens to accumulate Rb/sup 86/: iodoacetate, fluoride, cyanide, dinitrophenol, fluoroacetate, digoxin, and ouabain. It is concluded that the 4-hr uptake of Rb/ sup 86/m by lens incubated in a highly simplified medium provides a convenient and reproducible tool for studying cation transport in the lens. The results provided evidence for competitive irhibition by K and for the active transport of Rb into lens. The accumulation occurs against a concentration gradient, is temperature dependent, and is altered by competitive and metabolic inhibitors. (BBB)
- Research Organization:
- Washington Univ., St. Louis
- NSA Number:
- NSA-17-038716
- OSTI ID:
- 4634798
- Journal Information:
- Investigative Ophthalmology (U.S.) Changed to Invest. Ophthalmol. Visual Sci., Vol. Vol: 1; Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ACETATES
ACIDITY
ALANINE
AMINO ACIDS
AMMONIA
CALCIUM
CATIONS
CHOLINE
CORTISONE
CYANIDES
DIFFUSION
DNP
DRUGS
EYES
FLUORIDES
FLUORINE COMPOUNDS
GALACTOSE
GLUCOSE
GLYCINE
GLYCOSIDES
HORMONES
INSULIN
IODINE COMPOUNDS
IONS
LACTIC ACID
LENSES
LIPIDS
METABOLISM
ORGANIC ACIDS
ORGANIC NITROGEN COMPOUNDS
OUABAIN
OXYGEN
PHENOLS
POTASSIUM
QUANTITY RATIO
RABBITS
RUBIDIUM 86
SODIUM
SOLUTIONS
STEROIDS
SUGARS
TEMPERATURE
TISSUES
TOXICITY
TRACE AMOUNTS
VARIATIONS
VASOPRESSIN
VITAMIN B GROUP
VITAMINS