Glucose free fatty acids and

Cortisol is an important component of the body s response to physical and psychological stress. Nervous signals regarding stress are transmitted to the hypothalamus and the release of CRH is stimulated. The resulting increase in cortisol increases levels of glucose, free fatty acids, and amino acids in the blood, providing the metabolic fuels that enable the individual to cope with the stress. A potent inhibitor of this system is cortisol itself. This hormone exerts a negative-feedback effect on the hypothalamus and the adenohypophysis and inhibits the secretion of CRH and ACTH, respectively. 

Ahlborg G, Felig P, Hagenfeldt L, Hendler R, Wahren J. Substrate turnover during prolonged exercise in man. Splanchnic and leg metabolism of glucose, free fatty acids, and amino acids. J Clin Invest 1974 53 1080-1090. 

PPARy is a transcription factor which controls the expression of enzymes and proteins involved in fat and glucose metabolism. More importantly, stimulation of this receptor induces differentiation of preadipocytes to adipose cells. It is believed that the formation of additional, small fat cells lowers free fatty acids and hepatic triglycerides, thereby collecting insulin resistance. 

Since the bronchial tonus is under the relaxant influence of 62-adrenoceptor stimulation, especially unselective jS-blockers increase the respiratory resistance. In susceptible patients this might induce airway obstruction or even acute asthma. The blockade of jS2-adrenoceptors inhibits the mobilization of free fatty acids and glucose. This might result in hypoglycemia in diabetic patients. Furthermore, these patients will be not aware of the danger since most of the sympathetically mediated alerting symptoms like tachycardia are suppressed by the jS-blockers as well. jSi-Selective blockers show this type of side-effect less pronounced than unselective compounds. 

The major metabolic effects of caffeine are increase in free fatty acids and blood glucose concentration (223,224). 

MacKeown, B.A., Leatherland, J.F. and John, T.M. (1975). The effect of growth hormone and prolactin on the mobilisation of free fatty acids and glucose in the kokanee salmon, Oncorhynchus nerka. Comparative Biochemistry and Physiology 50B, 425-430. 

During the early minutes of exercise, carbohydrate (plasma glucose and muscle glycogen) is the predominant fuel for the working muscles. When the exercise is prolonged and intensive, carbohydrate remains a predominant fuel with lipids (plasma free fatty acids and muscle triglycerides) being of lesser importance. When the exercise is of moderate intensity, lipids eventually become the primary fuel as carbohydrate stores are reduced. 

Regulation of insulin secretion is affected by numerous factors, such as ftKxl, hormonal and neuronal stimuli, and innic mechanisms. In humans, the principal sub.slratc that stimulates the release of in.sulin from the islet /3-cells is glucose. In addition to glucose, other substrates (c.g., amino acids, free fatty acids, and ketone bodies) also can stimulate insulin. secretion directly. Secretin and ACTH can directly stimulate insulin secretion. Glucagon and other related peptides can increase the secretion of insulin, whereas somatostatin inhibits its secretion. 

Fig. 2. Metabolic interrelationships between free fatty acid and glucose metabolism. (Source Randle et al., 1963.)...

---