Studies on Lipid Metabolism in the Camel (Camelus Dromedarius).

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Tag Eldin Mirgani, Mirgani
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1. Lipids were extracted from the following tissues of single humped camels (Camelus dromedarius): hump, mesentery, perinephric, liver, kidney, heart, muscle, digesta and plasma. The normal lipid levels expressed as milligrams of total lipids per gram wet tissue were found to be as follows:- Hump 238, mesentery 273, perinephric 256, liver 27.3, heart 24.3 and kidney 23.3. Normal plasma lipid concentration was found to be 171 mg/ 100 ml. 2. The concentration of phospholipids, free cholesterol, triglycerides and cholesterol esters and the percentage contribution of each lipid class to total lipids were determined. It was found that phospholipids comprise 70% of the heart lipids, 58% of liver lipid, 55.8% of kidney lipids and 22% of plasma lipids. Cholesterol forms 46% of plasma lipids, 18% of liver lipids, 10% of kidney lipids and 9% of heart lipids. Triglycerides form 34.5% of plasma lipids, 26% of kidney lipids, 23.7% of liver lipids and 21% of heart lipids. Hump, mesentery and perinephiric adipose tissues mainly composed of triglycerides with a trace of phospholipids. 3. Four young male camels, each about four years old were starved for varying periods and were sacrificed at the end of the starvation period. Plasma lipid composition and fatty acid composition of plasma triglycerides were determined at intervals. Starvation caused a marked increase in concentration of the main plasma lipid classes. The increase in triglyceride concentration was 4-fold and in phospholipids and cholesterol each about 2-fold over that of the fed camels. Results of plasma lipid concentration support the view that stored fat which is mobilised in the form of free fatty acids is made available to the tissue for utilization in the form of lipoprotein triglycerides. 4. The fatty acid composition of the plasma triglycerides of the starved camels was similar to the fatty acid composition of the liver triglycerides. 5. Determination of tissue lipid concentration from the camel starved for 11 days showed that lipid concentration in the liver increases while that in all other tissue decreased. 6. Ketosis was not observed in the stared camels. 7. Results of tissue lipid composition, fatty acid patterns of triglycerides and the effect of fasting on these parameters are discussed in relation to findings in other animals. Similarities and differences are pointed out. 8. The behaviour of camel plasma lipoproteins in polyacrylamide gel electrophoresis was studied. The camel was found to have only one plasma lipoprotein class. Other mammals such as man and sheep have two main lipoprotein classes: alpha- and beta lipoproteins. 9. Lipids were extracted from lucerne (Medicago sativa) and Humra (Aristidia species) and the fatty acid composition of the extracted lipids were determined. Linolenic acid (36%) is the main fatty acid in lucerne followed by palmitic (23%). Palmitic acid (39%) is the main fatty acid in Humra followed by oleic acid (18.7%). 10. Lucerne and Humra were separately given to camels and the effect of the feed fatty acid on plasma triglyceride fatty acid composition was determined. Saturated fatty acid of the feed was found to have marked effect while unsaturated fatty acids had relatively little effect on plasma triglyceride fatty acid composition. 11. Osmotic stability of camel erythrocytes in hypotonic salt solutions was confirmed. The erythrocyte lipid composition, which represent cell membrane lipids, were determined. Erythrocyte phospholipid classes were separated by TLC and the proportions were compared with those of other mammals. These studies were aimed at finding any peculiarity erythrocyte lipids which would explain the osmotic stability. Except for high proportion of phosphatidylserine in camel phospholipids, camel erythrocyte lipids were found to be similar to other mammalian erythrocytes. 12. The high blood glucose concentration in the camel relative to other ruminants was confirmed. The remarkable ability of the camel to maintain a high blood glucose level during starvation was noted. 13. The behaviour of camel serum proteins on electrophoresis on paper and in polycrylamide gel was studied. 14. The enzyme lipoprotein lipase, which is important in regulation of lipid metabolism in mammals, was prepared from camel tissues as an acetone- ether extract. The assay of the enzyme activity using a radioactive substrate was developed. 15. The effect of starvation on tissue lipoprotein lipase activity was investigated. Starvation caused a marked decrease in hump lipoprotein lipase activity and a marked increase in the enzyme activity of other tissues. 16. The increase in enzyme activity of the muscle was more than 4- fold. 17. These findings are consistent with the physiological role of lipoprotein lipase.
Studies on Lipid Metabolism in the Camel (Camelus Dromedarius