Beta‐adrenergic blockade restores glucose's antiketogenic activity after exercise in carbohydrate‐depleted athletes.

Abstract

SUMMARY1. The development of post-exercise ketosis is not abolished by the ingestion of glucose immediately after exercise, despite inducing high insulin/glucagon ratios in the peripheral (and therefore by implication in the portal) blood.2. To investigate the possibility of autonomic control of the liver influencing its sensitivity to the major counter-regulatory hormones, we administered 50 g glucose, either on its own, or together with 0 5 mg prazosine, 40 mg propranolol, or 15 mg propantheline, to forty-seven 48 h carbohydrate-starved athletes who had just run 25 km.3. The blood 3-hydroxybutyrate concentration rose from 0 30 + 0 05 (mean + S.E. of mean) to 0-52 + 0-08 mmol/l with exercise, and then to 1-32 + 0-40 mmol/l at 6 h after exercise in subjects who had ingested only glucose after exercise.4. The effects of prazosine and propantheline on the blood ketone body concentration at 2 h after exercise was not statistically significant. Propranolol, on the other hand, significantly lowered the blood 3-hydroxybutyrate concentration (compared with controls) to 0 09+0 03 mmol/l at 3 h (P < 0-01), and 0-35 +0-08 mmol/l at 6 h (P < 0X01) after exercise.5. The plasma insulin, glucagon, glucose and free fatty acid concentrations were unaffected by propranolol, indicating that the antiketogenesis was the result of a direct effect on ketone body metabolism.6. Since /1-adrenergic blockade has not previously been shown to have antiketogenic activity, except in somatostatin-induced hyperketonaemia, it is concluded that its effectiveness in post-exercise ketosis can probably be ascribed to a functional hepatic insulin and glucagon deficiency.

Carbohydrate homeostasis and post‐exercise ketosis in trained and untrained rats.

“…The high degree of correlation between the blood ketone body concentration and simultaneous liver glycogen content (r = -0-88) suggests that the link between the two is very close indeed after exercise. Such a close link has never previously been shown to exist between the post-exercise blood ketone body concentration and any other biochemical variable measured to date (Johnson et al 1969 a, b;Johnson & Rennie, 1973;Winder et al 1973;Rennie et al , 1976Holloszy et al 1978;Koeslag et al 1980Koeslag et al , 1982Koeslag et al , 1985Beattie et al 1985;Adams et al 1987;Adams & Koeslag, 1989). The nature of the link, and the mechanisms which drive the system, remain matters for speculation beyond the scope of this article.…”

“…We confined our enquiry to the measurement of the blood 3-hydroxybutyrate and tissue glycogen concentrations because we could only obtain very small quantities of blood from each rat with certainty, and because the plasma hormone, glucose, free fatty acid, and acetoacetate concentrations have already been studied exhaustively without leading to clear conclusions (Johnson et al 1969a, b;Johnson, Rennie, Walton & Webster, 1971;Johnson & Walton, 1972;Johnson & Rennie, 1973;Winder et al 1973;Rennie, Winder & Holloszy, 1976;Holloszy, Winder, Fitts & Rennie, 1978;Koeslag, Noakes & Sloan, 1980, 1982Beattie & Winder, 1984Koeslag, Levinrad, Lochner & Sive, 1985;Adams, Irving, Koeslag, Lochner, Sandell & Wilkinson, 1987). The effects of dietary manipulation on the tissue glycogen levels and post-exercise ketosis are described elsewhere (Adams & Koeslag, 1989).…”

Glycogen Metabolism and Post‐exercise Ketosis in Carbohydrate‐restricted Trained and Untrained Rats

“…The hormones which might influence the development of post-exercise ketosis have been shown to act paradoxically during the recovery from exercise (Koeslag, Noakes & Sloan, 1982;Koeslag, Levinrad, Lochner & Sive, 1985;Adams, Irving, Koeslag, Lochner, Sandell & Wilkinson, 1987), and to change with the diet in the same way that post-exercise ketosis changes with the previous day's carbohydrate intake (Koeslag et al 1980). The present findings therefore support the hypothesis that the availability of mobilizable carbohydrate after exercise is an important (but probably not the sole) determinant of the development of post-exercise ketosis.…”

Bacterial polyhydroxyalkanoates-eco-friendly next generation plastic: Production, biocompatibility, biodegradation, physical properties and applications

“…Their breakdown products are 3-hydroxyacids, which are naturally found in animals. Such as PHB is biocompatible, which is not surprising when considering the fact that R-3-hydroxybutyric acid is a normal constituent of blood at concentrations between 0.3 and 1.3 mM (31,205,206) and is also found in the cell membrane of eukaryotes (207). These PHAs have the potential to become important and very useful compounds for medical applications such in wound management used as surgical suture, skin substitutes, nerve cuffs, surgical meshes, implants, gauzes, staples, gauzes, swab, lubricating powders (29,30,38), blood vessels, tissue scaffolds and bone fracture fixation plates (3,251,252).…”

“…A number of studies have shown that PHB take part in formation of transmembrane ion channel complexes in eukaryotic and prokaryotic cell membranes (31,(205)(206)(207). Interestingly, degradation of PHB polymer results ultimately in the production of, R-3-hydroxybutyric acid which also is a normal constituent of blood at concentrations between 0.3 and 1.3 mM and known to be associated with ketone body formation.…”