Hepatic metabolism during porcine malignant hyperthermia (MH) was investigated in seven Pietrain pigs. The estimated hepatic blood flow decreased during MH, but an increase in oxygen extraction enabled the splanchnic oxygen uptake to be maintained. There was a large release of glucose and potassium from the liver in MH which made an important contribution to the hyperglycaemia and hyperkalaemia. Measurement of hepatic uptake of the precursors of gluconeogenesis, lactate, glycerol and alanine, showed that glucose efflux from liver was derived mainly from glycogenolysis. Lactate uptake by the liver increased during MH, and there was no evidence of hepatic lactate production during the profound acidosis as suggested by in vitro studies with the isolated liver. There was no evidence of major abnormality of hepatic function during porcine MH.

As part of a study of the metabolic effects of long distance riding the results of biochemical analyses of blood samples taken from horses before, immediately after and one hour after an 80 km ride are reported. The results show that the horses were moderately dehydrated, they were working aerobically using fats as metabolic substrates and blood glucose was reduced. There was no evidence of post exercise ketosis and circulating alanine levels fell. Metabolic hormone levels are reported and are related to the availability of substrates for gluconeogenesis. There was evidence of reduced kidney and liver function which was showing little sign of recovery in the first hour after the ride.

No abstract

Blood samples were taken from 15 horses before and after a 50-mile ride to examine the changes occurring in some biochemical constituents. There was a significant (P less than 0.05) decrease in plasma potassium, calcium and magnesium concentrations and a rise in inorganic phosphate but there was no alteration in plasma sodium, chloride or protein levels or change in haematocrit. After the ride there was a highly significant (P less than 0.01) fall in blood glucose corresponding with increased lipolysis and a rise in plasma free fatty acids (P less than 0.001) and glycerol (P less than 0.001). There was a modest increase in blood lactate and a rise in plasma creatine phosphokinase. The results of this preliminary investigation are discussed in relation to the problem of exhaustion in horses during endurance rides.

Summary Blood samples were taken before and immediately after 80 km and 40 km rides held on consecutive days and analysed for haematocrit, blood glucose and lactate, plasma sodium, potassium, calcium, albumin, free fatty acids (FFA), glycerol, bicarbonate, insulin, cortisol, glucagon, urea, creatinine, uric acid, bilirubin and alkaline phosphatase. Unusually hot weather probably contributed to haemoconcentration with a significant (P<0.001) increase in haematocrit and plasma albumin. A fall in blood glucose, with a rise in FFA and glycerol were consistent with long distance riding and were associated with a reduction in plasma insulin and a rise in cortisol and glucagon. The results suggested that the horses were working aerobically and the small increase in blood lactate was likely to be a result of reduced tissue perfusion. Plasma urea, creatinine and bilirubin increased during the 80 km ride and were still high the next morning. Blood samples were taken from 2 horses that became exhausted and were forced to retire and the results from these animals indicate the slow rate of recovery. It is suggested that haemoconcentration with reduced tissue perfusion might contribute to exhaustion during long distance exercise and that the speed of recovery might be improved by the intravenous administration of balanced electrolyte solutions. Résumé Avant et immédiatement après des raids de 40 et de 80 km effectués en deux jours consëcutifs, on a prélevé des échantillons de sang. Ces échantillons ont été analysés pour y rechercher l'hématocrite, la glycémie, la lactacidèmie, le sodium, le potassium et le calcium plasmatiques, l'albumine, les acides gras non saturés, la bilirubine et les phosphatases alcalines. Un temps particulièrement chaud favorisa probablement une hémoconcentration entraînant une élévation significative (P <0.001) de l'hématocrite et de l'albumine du plasma. On constata une chute du glucose sanguin, une élévation des acides gras non saturés et du glycerol associés à la diminution de l'insuline et à l'augmentation du cortisol et du glucagon. Ces résultats indiqueraient que les chevaux ont travaillé en aérobie; une légère élévation des lactates sanguins paraîtrait indiquer une perfusion tissulaire réduite. L'urée plasmatique, la créatinine et la bilirubine augmentèrent durant l'épreuve de 80 kilomètres et leurs niveaux étaient encore élevés le lendemain matin. Des prélèvements sanguins obtenus sur deux chevaux, épuisés au point d'abandonner, ont permis de constater la lenteur de la récupération. On suppose que l'hémoconcentration, parce qu'elle réduit la perfusion des tissus, peut contribuer à l'épuisement lors des raids. On pense que la vitesse de récupération peut étre améliorée par l'administration intra‐veineuse de solutions équilibrées d'électrolytes. Zusammenfassung Vor und unmittelbar nach Distanzritten über 80 und 40 km an aufeinanderfolgenden Tagen wurde Blut entnommen und untersucht auf Haematokrit, Blutglucose, Laktat, Plasmanatrium, ‐kalium, ‐calcium, ‐albumin, freie Fettsäuren, Glycerin, Bicarb...