PMID- 6452426
OWN - NLM
STAT- MEDLINE
DCOM- 19810613
LR  - 20141120
IS  - 0146-0404 (Print)
IS  - 0146-0404 (Linking)
VI  - 20
IP  - 4
DP  - 1981 Apr
TI  - Age and the control of glycolysis in the rat lens.
PG  - 457-66
AB  - Previous studies with lens dispersions indicated that the rate-limiting step in 
      glycolysis shifts from hexokinase (HK) in the young lens to phosphofructokinase 
      (PFK) in older lenses. Because the concentrations of the complex controlling 
      factor for these enzymes could not be reproduced reliably in homogenates, the 
      question of age-related control of glycolysis was re-examined in intact lenses. 
      Toward this end, the levels of several metabolites of glucose were measured in 
      fresh and incubated clear lenses. Of the substrates measured per fresh lens, only 
      one changed significantly with age; fructose diphosphate was increased. When 
      lenses were incubated in 2 to 12 mM glucose, the lactate production per lens was 
      not significantly different with age. Together these results suggested that the 
      glycolytic mass of the lens was constant with age. In both young and older 
      lenses, increases in glucose in the medium led to increases in both glucose and 
      glucose-6-phosphate in the lens. The lack of corresponding increase in lactate 
      production suggested that the regulatory step lay downstream from HK, probably at 
      PFK. This finding was corroborated by evidence that the initial acceleration of 
      lactate production by the addition of cyanide (the Pasteur effect) was 
      accompanied by decreases in the substrates of PFK, glucose-6-phosphate and 
      fructose-6-phosphate. A secondary disinhibition of HK, as indicated by decreased 
      lens glucose, became apparent after longer incubation with cyanide. This 
      suggested that after disinhibition of PFK, HK became rate-limiting until the 
      level of glucose-6-phosphate fell enough to allow the disinhibition of the latter 
      enzyme as well. Thus PFK seemed to be the primary regulatory step in aerobic 
      glycolysis in lenses of rats from 1 to 12 months of age.
FAU - Gillis, M K
AU  - Gillis MK
FAU - Chylack, L T Jr
AU  - Chylack LT Jr
FAU - Cheng, H M
AU  - Cheng HM
LA  - eng
GR  - EY00089/EY/NEI NIH HHS/United States
GR  - EY01276/EY/NEI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Invest Ophthalmol Vis Sci
JT  - Investigative ophthalmology & visual science
JID - 7703701
RN  - 0 (Cyanides)
RN  - 0 (Fructosediphosphates)
RN  - 0 (Lactates)
RN  - EC 2.7.1.11 (Phosphofructokinase-1)
RN  - IY9XDZ35W2 (Glucose)
SB  - IM
MH  - Aging
MH  - Animals
MH  - Cyanides/pharmacology
MH  - Fructosediphosphates/metabolism
MH  - Glucose/*metabolism
MH  - *Glycolysis/drug effects
MH  - In Vitro Techniques
MH  - Lactates/metabolism
MH  - Lens, Crystalline/enzymology/*metabolism
MH  - Male
MH  - Phosphofructokinase-1/metabolism/pharmacology
MH  - Rats
EDAT- 1981/04/01 00:00
MHDA- 2001/03/28 10:01
CRDT- 1981/04/01 00:00
PHST- 1981/04/01 00:00 [pubmed]
PHST- 2001/03/28 10:01 [medline]
PHST- 1981/04/01 00:00 [entrez]
PST - ppublish
SO  - Invest Ophthalmol Vis Sci. 1981 Apr;20(4):457-66.