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Title: Studies on the intermediary metabolism of the ox, with special reference to the sympatho-adrenal system
Author: Robertshaw, David
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1965
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Abstract:
A study is made of the interrelationships of the concentrations of glucose, potassium, adrenaline, noradrenaline and the lower volatile fatty acids (VFA) in the blood of the ox. An examination of biological and chemical methods for adrenaline and noradrenaline determination in the Jugular rein plasma of the ox revealed that a fluorimetric method involving condensation with ethylenediamine was suitable. Polythene cannulas, implanted in the Jugular vein were used to obtain serial blood samples without any psychic disturbance of the experimental animals. Under these conditions of blood sampling the mean normal concentration of adrenaline in bovine plasma was found to be 0.31 (range 0.03-0.7) mug/1, and that of noradrenaline 2.5 (range 0.4-4.6) mug/1. Intravenous administration of insulin caused blood glucose concentration to fall, and the plasma concentrations of adrenaline end noradrenaline rose when blood glucose levels reached acritical level between 15 and 25 rag/100 ml. The increase in plasms adrenaline concentration was greater than that of noradrenaline. The increase In plasma noradrenaline concentration during hypoglycemia is peculiar to the ox, and the physiological Importance of noradrenaline relative to that of adrenaline was assessed by determining Its ability to raise the blood glucose concentration. It was found that adrenaline:noradrenaline hyperglycaemic ratios for the ox ranged from 0.79 to 6.58, figures which are much lower than those of other species. It was concluded that in the ox the release of noradrenaline during insulin hypoglycaemic is physiologically significant. Insulin administration caused a fall in plasma VFA levels, which was quantitatively indistinguishable from a fall that occurred following glucose administration. Arterio-venous studies suggested that this effect of insulin and glucose was not due to any enhancement of utilisation of VTA by the extrahepatic tissues. Other workers have shown that intravenous administration of sodium propionate or sodium butyrate would relieve hypoglyeaemic convulsions in ruminant animals. The possibility that this may here been the result of sympatho-adrenal stimulation was Investigated. Intravenous sodium propionate end occasionally Intravenous sodium butyrate administration resulted in elevated plasma levels of adrenaline and noradrenaline. Sodium aoetate administration caused e depression in plasms adrenaline and noradrenaline levels especially the adrenaline levels. Intravenous glucose administration alao depressed plasma levels of adrenalins and noradrenaline. It was concluded that, with the possible exception of sodium propionate, the eynpatho-edrenal system of the ex plays little part in producing the changes in blood glucose that result from intravenous injections of the sodium salts of the lower fatty acide. The rate of disappearance from the cireulatlon of the injected aeetate end propionate wee inversely related to the initial plasms VFA and blood glucose levels respectively. The intravenous administration of insulin, glucose, or the eodlum salts of the lower fatty acids all produced hypokalemia. Studies on the intermediary metabolism of Bos indicus. a species of cattle indigenous to tropleal arses and of Boa taurua. cattle indigenous to temporete cones, revealed that Bos Indiana possessed higher normal bleed glucose levels, e lower sensitivity to insulin, slower utilisation of intravenously administered glucose and a lower plants potassium concentration than Bos taurus. These differences were attributed to a higher degree of adrenocortical activity in Bos indious. The results of these studies ere coopered to similar studies in non-ruminant animals, taking account of the differences in their dietary intake and node of digestion. The comparative studies on the two species of Bos are discussed In relation to their physiological responses to their environment.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.776707  DOI: Not available
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