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ARTICLES
Year : 1983  |  Volume : 31  |  Issue : 7  |  Page : 882-883

A study of adenosine triphosphatase activity in human normal, immature, mature and hypermature cataractous lenses


JLN Medical Gollege and Hospital, Ajmer, Rajashthan, India

Correspondence Address:
G K Sharma
Department of Ophthalmology, J.L.M. Medical College and Hospital, Ajmer (Rajasthan)
India
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Source of Support: None, Conflict of Interest: None


PMID: 6152694

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How to cite this article:
Sharma G K, Mathur S S, Kabra S G, Malik V K. A study of adenosine triphosphatase activity in human normal, immature, mature and hypermature cataractous lenses. Indian J Ophthalmol 1983;31, Suppl S1:882-3

How to cite this URL:
Sharma G K, Mathur S S, Kabra S G, Malik V K. A study of adenosine triphosphatase activity in human normal, immature, mature and hypermature cataractous lenses. Indian J Ophthalmol [serial online] 1983 [cited 2020 May 24];31, Suppl S1:882-3. Available from: http://www.ijo.in/text.asp?1983/31/7/882/29692

Table 1

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Table 1

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Exact mechanism of the development of cataract in human lens is not known, even though several contributory factors have been elucidated. Na + K + and Mg ++ dependent adenosine triphosphatase activity in the lens has been held responsible for cataractous changes by its controlling function over cat­ion transport mechanism [1],[2]. The present study was undertaken to evaluate the relative ATPase activity in normal and cataractous lenses at various stages of opacification.


  Material and methods Top


100 human lenses, 25 each of normal (from cadavers) immature, mature and hyperma­ture cataracts were studied for total ATPase and Na + K + and Mg ++ dependent ATPase activity by estimating the inorganic phospho­rous liberation by Fiske & Subbarow method[3] from adenosine triphosphate substrate. The proteins were estimated by Biuret method[4].


  Observations Top


Diferent fractions of ATPase activity measured in different groups of lenses are presented in [Table - 1].


  Discission Top


In the present study decreased enzyme activity of total ATPase, Mg ++ and Na + K + dependent ATPase was observed in imma­ture, mature and hypermature cataractous lenses in increasing order as compared to nor­mal lens.

Nordman & Kleithi[5] found a continuous tendency of decreasing Na + K + ATPase in human lenses developing senile cataract and rimilar observations were made in our study.

Mayman et a1[6], observed lowering of Na + K + dependent ATPase activity with in­vitro production of cataract by steroids which led to postulate the hypothesis that steroids inhibit Na + K + dependent ATPase causing disruption of active cation pump and con­tributing to formation of cataract.

Unakar & Tsui[7],[8]bserved a gradual decrease in Na + K + dependent ATPase act­ivity in the lenses of galactose fed animals using ultrastructural cytochemistry. Obser vatibns in the present study reflect a statis­tically significant pattern of ATPase enzyme activity (both Na + K + and Mg ++ dependent) during the process of cataract formation from immature to the stage of hypermaturity. The enzymes activity was highest in normal len­ses. Hence the decrease in enzyme activity may be considered an important factor in the etiology of development of cataract.


  Summary Top


The present study comprised 100 human lenses of normal, immature, mature and

hypermature type of cataractous lenses from patients operated upon in our institution while normal lenses were collected from enucleated eyes of dead bodies. The activity of total adenosine triphosphatase, Na +K + and Mg ++ dependent ATPase was estimated and the normal lenses showed highest activity of this enzyme while a progressive and statis­tically significant decline of its activity was observed in immature, mature and hyperma­ture cataractous lenses which may hold a clue to the etiology of cataract formation.

 
  References Top

1.
Skou, J.C. (1957) : Biochem. Biophys. Acta. 23:394.  Back to cited text no. 1
    
2.
Skou, J.C. (1960) : Biochem. Biophys. Acta, 42:6.  Back to cited text no. 2
    
3.
Fiske, C.H. and Subbarow, Y. (1925) : J. Biol. Chem. 66:375.  Back to cited text no. 3
    
4.
Biuret : Method for differential proteins-micro­ analysis in medical biology by King, E.J. and Wootton, I.D.P. (1956) : 3rd Ed. pp 57-60, J. & A Churchill Ltd., London W.I.  Back to cited text no. 4
    
5.
Nordman, J. and Kleithi, J. (1976) : Arch. Ophthal (Paris). 36/6-7:523-528.  Back to cited text no. 5
    
6.
Mayman, C.I.; Millar, D. and Tijerina, M.I.: (1979): Acta. Ophthal. (Copenh), 57 (6):1107-16.  Back to cited text no. 6
    
7.
Unakar, N.J. and Tsui, J. (1980): Invest Ophthal. Vis. Sci. 19(4):378-85.  Back to cited text no. 7
    
8.
Unakar, N.J. and Tsui, J. (1980) : Invest. Ophthal. Vis. Sci. 19(6):630-41.  Back to cited text no. 8
    



 
 
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