Year : 1983 | Volume
: 31 | Issue : 7 | Page : 882--883
A study of adenosine triphosphatase activity in human normal, immature, mature and hypermature cataractous lenses
GK Sharma, SS Mathur, SG Kabra, VK Malik
JLN Medical Gollege and Hospital, Ajmer, Rajashthan, India
G K Sharma
Department of Ophthalmology, J.L.M. Medical College and Hospital, Ajmer (Rajasthan)
|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;31:882-883
|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 2021 Sep 21 ];31:882-883
Available from: https://www.ijo.in/text.asp?1983/31/7/882/29692
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 ,. The present study was undertaken to evaluate the relative ATPase activity in normal and cataractous lenses at various stages of opacification.
MATERIAL AND METHODS
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 from adenosine triphosphate substrate. The proteins were estimated by Biuret method.
Diferent fractions of ATPase activity measured in different groups of lenses are presented in [Table 1].
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 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, 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,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.
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.
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