|Year : 1981 | Volume
| Issue : 4 | Page : 325-329
Enzyme lactic dehydrogenase (LDH)
MR Chadha1, Kartar Singh2, Baljit Singh1
1 Department of Ophthalmology, Medical College, Amritsar, India
2 Department of Biochemistry, Medical College, Amritsar, India
M R Chadha
MS, MAMS, DOMS C-2, New Medical College, Amritsar
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chadha M R, Singh K, Singh B. Enzyme lactic dehydrogenase (LDH). Indian J Ophthalmol 1981;29:325-9
In order to understand the biochemical basis of cataract formation the present study was carried out to determine the changes in lactic dehydrogenase activity in senile cataractous lenses, cataractous lenses of younger age group and with some systemic or ocular complaints.
| Material and methods|| |
100 patients were picked up from those who were admitted in Ram Lal Eye & ENT Hospital, Amritsar (India) for cataract extraction. Thorough examination was done and cataractous lenses from these patients and normal lenses were divided into four groups [Table - 1]
Intra-capsular extraction of lens was done in all patients and in younger patients, intracapsular extraction was done by the process of zonulolysis. The lens having capsule intact, were included in the study and just after operation macroscopic examination was done and lens were chilled in ice. The normal lenses were obtained from the patients who died in Shri Guru Tegh Bahadur Hospital, Amritsar, age varied between 39-50 years. Both types of lenses were either analysed on the same day or stored at-10°C for analysis on next day. After weighing the lens 5% homogenate of the lens was prepared in normal saline using potter-Elvehjem homogenizer. After centrifugation, supernatant was stored in ice. One ml of supernatant was used for estimation of soluble proteins which were estimated by Biuret method of Reinhold (1953). For the estimation of total lactic dehydrogenase activity 0.1 ml of supernatant was taken and lactic dehydrogenase activity was determined by King's method (1965) and readings were taken at 510 mu in a Bausch and Lomb Spectronic 20 colorimeter. Remaining supernatant was heated to 60° C for one hour and again estimation was performed same way and thus heat stable lactic dehydrogenase was determined. The heat labile activity of the enzyme was calculated by substracting the heat stable activity from that of the total activity of the enzyme.
| Observations|| |
The results of wet weight in normal and cataractous lens are shown in [Table - 1].
Wet weight of the lens increases with cataract formation and it is significantly increased in hypermature cataractous lenses (P>.05).
The soluble proteins are significantly lowered (P<.001) in all types of cataract formation in the lens. The maximum decrease in soluble proteins was observed in hypermature cataractous lens [Table - 2].
Total lactic dehydrogenase activity is lowered in all types of cataract of all ages and maximum lowering of lactic dehydrogenase activity was observed in hypermature cataract [Table - 3]. Values of heat stable and heat labile lactic dehydrogenase activities are also lowered in all types of cataractous lenses [Table - 4][Table - 5]. In normal lenses heat stable lactic dehydrogenase fraction was 39.9 per cent of the total activity and heat labile lactic dehydrogenase fraction was 60.1 per cent. Cataract formation leads to shift in the heat stable fraction and it ranged from 41.90 to 51.50 per cent and heat labile fraction varies from 48.49 to 59.01 per cent. It means even after heating at 60°C for one hour 46.63 per cent lactic dehydrogenase activity is retained in the cataractous lenses [Table - 6].
| Discussion|| |
The increase in wet weight of hypermature lenses as compared to normal lenses was observed in this study. The increase in wet weight may be explained that usually the hypermature senile cataractous lenses are swollen, globular and are of soft type of cataract due to inhibition of water. Cataract formation itself might decrease the concentrations of soluble proteins in the lens. The present study also supports this hypothesis as it was observed that in cataract of younger age group soluble proteins are significantly lowered as compared to normal lenses of same age group.
In this study level of lactic dehydrogenase activity in normal lenses were lower as compared to and Mariani et al Nath et al. It may be due to the fact that normal lenses included in this study were belonging to higher age group i.e. 39-50 years. The data indicate a decrease in total lactic dehydrogenase activity in human cataract irrespective of age and also it has been observed that there is gradual lowering of lactic dehydrogenase activity depending upon maturity of cataract.
Lactic dehydrogenase activity might be low due to leakage of the enzyme along with the other soluble proteins following the post cataractous breakdown of lens fibres. The changes noted in lactic dehydrogenase activity in cataract lenses may lead to increase in lactic acid resulting in a change in pH which might be partly responsible for the precipitation of proteins present in the lens and opalescence in cataract lens. However, the role of lactic dehydrogenase, its heat resistant properties and its relationship to the process of cataract formation is not very clear and needs further investigation.
| Summary|| |
This study has been carried out in eleven (l1) normal lenses and one hundred various types of cataractous lenses in human beings. Sixty cataractous lenses at various stages of maturity i e., immature, mature and hypermature were divided in 3 groups, each group having 20 lenses. Twenty (20) cataractous lenses from patients between 30-50 years of age were also analysed. The lens wet weight, soluble proteins, lacticdehydrogenase were studied. Total soluble proteins decrease has been observed in all types of cataractous lenses. A significant decrease in lacticdehydrogenase have been noted in all types of cataractous lenses.
| References|| |
Maraini, G., Santori, M. and Carta, F., 1967., Expt. Eye Res. 6, 126-129.
Nath, R., Srivastava, S.K. and Singh, K., 1969. Ind. J. Of Exp. Biology. 7 (1), 25-26.
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6]