Oxygen Consumption In Dogs Research Articles

Effects of two alpha-adrenoceptor antagonists, nicergoline and phentolamine, on myocardial oxygen consumption in the dog.

We compared the effects of two alpha-adrenoceptor antagonists, nicergoline and phentolamine, on myocardial oxygen consumption (MVO2) in open-chest dogs. Intravenous nicergoline, 2 micrograms/kg/min for 30 min, reduced blood pressure from 130 +/- 6 to 100 +/- 2 mm Hg, did not change heart rate, and reduced MVO2/beat from 63.1 +/- 6.6 to 43.6 +/- 4.0 microliters (p less than 0.05, compared with control saline-infused and phentolamine-treated dogs). Intravenous phentolamine, 8 micrograms/kg/min, reduced blood pressure from 123 +/- 6 to 95 +/- 8 mm Hg and increased heart rate from 199 +/- 4 to 235 +/- 9 beats/min ( p less than 0.05, compared with control and nicergoline-treated dogs). MVO2/beat did not change, but MVO2 increased from 11.1 +/- 1.5 to 13.1 +/- 2.0 ml/min (p less than 0.05, compared with nicergoline-treated dogs). These results suggest that nicergoline may be preferable to phentolamine in patients in whom it is important to avoid any increase in MVO2.

Maximum oxygen consumption in dogs during muscular exercise and cold exposure.

Maximum oxygen consumption for a short exhaustive work (Ex VO2 max) and for a severe cold stress (C VO2 max) were investigated in 8 dogs. Heart rate, plasma catecholamines and substrate concentrations were measured under both conditions. Mean C VO2 max was lower than mean Ex VO2 max. Heart rate and plasma lactate were also lower during cold exposure than during exercise. Average plasma epinephrine concentrations were not significantly different and average plasma norepinephrine concentrations were similar under C VO2 max and Ex VO2 max conditions. A positive correlation was found between plasma lactate and epinephrine concentrations measured under both conditions. It may be assumed that maximum oxygen consumption during muscular exercise is higher than during shivering thermogenesis. This difference does not seem to be due to differences in the involvement of the sympathico-adreno-medullary system.

The effect of stored blood on mesenteric oxygen extraction during endotoxin shock

Storage of blood in acid-citrate-dextrose (ACD) solution gradually depletes red cell 2,3-diphosphoglycerate (DPG) and increases the affinity of hemoglobin for oxygen. We examined the effect of exchange transfusion of DPG-depleted blood on mesenteric blood flow and oxygen consumption in dogs subjected to endotoxin shock. Two groups of 6 dogs each were anesthetized and subjected to exchange transfusion with either fresh ACD blood or 21-day-old ACD blood prior to administration of Escherichia coli endotoxin (2 mg/kg). Mesenteric blood flow, arteriovenous oxygen content difference and systemic arterial blood pressure were monitored continuously before and for 60 min after endotoxin. Mesenteric blood flow was reduced from 250 +/- 21 ml/min before endotoxin to 114 +/- 15 ml/min at 5 min, 157 +/- 29 ml/min at 30 min, and 112 +/- 17 ml/min at 60 min after endotoxin in the dogs exchanged with fresh blood. Corresponding values for intestinal oxygen consumption were 10.4 +/- 1.0, 7.5 +/- 0.8, 8.4 +/- 1.0, and 6.8 +/- 0.7 ml/min. In dogs transfused with 21-day-old blood, pre-endotoxin blood flow was 208 +/- 2ml/min and declined to 115 +/- 12, 93 +/- 5, and 80 +/- 8 ml/min at 5, 30, and 60 min post-endotoxin. Corresponding values for intestinal oxygen consumption were 8.1 +/- 0.9, 6.6 +/- 0.7, 6.2 +/-0.5, and 5.5 +/- 0.7 ml/min. There was no significant difference (p greater than 0.1) in responses of blood flow or oxygen consumption to endotoxin shock between the two groups of dogs. These findings indicate that exchange transfusion with DPG-depleted blood does not impair oxygen extraction by the ischemic intestine.

Clinical Physiology: Effects of Nicotine and Inhalation of Cigarette Smoke on Total Body Oxygen Consumption in Dogs

Clinical Physiology: Effects of Nicotine and Inhalation of Cigarette Smoke on Total Body Oxygen Consumption in Dogs

Influence of althesin on coronary blood flow and myocardial oxygen consumption in dogs.

Glaxo CT 1341 (Althesin) is a new steroid anaesthetic agent dissolved in Cremophor EL. Its influence on hemodynamics was studied in dogs, especially regarding the myocardial contractility, coronary perfusion and myocardial oxygen consumption.The unpremedicated experimental animals were induced with 3 mg/kg piritramide intravenously and normoventilated with a mixture of 70% N2O and 30% O2. All animals were pretreated with a powerful antihistaminic agent (Tavegilr̀) in order to block reactions to histamine released by Cremophor EL. Five hours later the animals received single intravenous doses of Althesin (1.0 and 2.0 mg/kg).Significant hemodynamic changes (P < 0.025‐0.0005) were caused by 2.0 mg/kg. Heart rate, cardiac output and mean pulmonary pressure increased, total peripheral resistance decreased; while central venous pressure, mean aortic pressure and renal blood flow remained unchanged. The resulting increased cardiac work caused a rise in coronary blood flow of 88%, an increased myocardial oxygen consumption of 66% and a decreased coronary resistance of 48%. As coronary arteriovenous difference in oxygen decreased slightly, Althesin has coronary dilatory properties. Myocardial depression was seen in a marked fall of dp/dtmax (the rate of change of the left ventricular pressure) (30%), in a decreased stroke volume and in an increased left ventricular end‐diastolic pressure. Maximal hemodynamic responses occurred within the first minute after injection and returned to their preinjection levels after approximately 20 min.A recommended dose in man is 2 mg/kg Althesin Myocardial depression and increased oxygen consumption suggest a cautious use of Althesin in cases of heart and coronary insufficiency.

Free fatty acids and oxygen consumption in dogs.

High arterial concentrations of free fatty acids (FFA) induced by intravenous (i. v.) infusion of a fat emulsion, Intralipid “Vitrum” in heparinized dogs, raised total body oxygen consumption, on average, by 17 per cent (p<0.001) and myocardial oxygen consumption (MVO2), on average, by 19 per cent (<0.025). On the other hand, MVO2 remained unchanged by high plasma-concentrations of triglycerides, induced by i. v. infusion of Intralipid in non-heparinized dogs.

A device for measuring oxygen consumption in the dog

A simple modification of a Collins 13.5-liter spirometer is described whereby oxygen consumption in dogs can be continuously monitored.

THE EFFECT OF A HEART EXTRACT ON THE CORONARY BLOOD FLOW AND MYOCARDIAL OXYGEN CONSUMPTION IN DOGS.

THE EFFECT OF A HEART EXTRACT ON THE CORONARY BLOOD FLOW AND MYOCARDIAL OXYGEN CONSUMPTION IN DOGS.

Oxygen consumption in dogs as influenced by the altered metabolism of diabetes mellitus.

The question of the total energy production in the human diabetic has been studied extensively by Benedict and Joslin (1, 2) and by Allen and Du Bois (3). It generally has been agreed that energy metabolism in mild cases of diabetes is normal, and that in the more severe cases is found increased when determined on the basis of kilogram of body weight. The lack of a satisfactory standard of comparison between diabetic and nondiabetic subjects hampered much of the earlier work in this field and led to disagreement regarding interpretation of data. Benedict and Joslin (1, 2), using the Harris-Benedict prediction standard, reported increases in metabolic rate of diabetic subjects of between 15 and 20 per cent. Lusk (4) criticized these data and computed that the increase in metabolism did not exceed 5 per cent. With the general acceptance of the more valid Du Bois standard (5) comprehending body surface area, many of the earlier data ascribing an increase in metabolic rate to diabetes have been recalculated and shown to be erroneous. More recent publications likewise have been of conflicting nature reporting increases in metabolic rate as great as 40 per cent and decreases of 32 per cent in severe clinical diabetes mellitus (6-9). In the pancreatectomized dog, on the other hand, respiratory metabolism generally has been found to be increased (10-12). However, attempts at direct comparison between this type of acute canine diabetes and the disease as it occurs in humans is illogical in view of the typical alteration in fatty acid metabolism following pancreatectomy. We are not aware that oxidative metabolism has been measured previously in the alloxan diabetic animal which provides a metabolic defect more nearly identical with that occurring in human diabetes mellitus. That an increase in oxygen consumption in dia-

Endocrine influences on cardiac output and oxygen consumption in dogs: White, H. L., Heinbecker, P., and Rolf, D.: Am. J. Physiol. 151:239 (Dec.), 1947

Endocrine influences on cardiac output and oxygen consumption in dogs: White, H. L., Heinbecker, P., and Rolf, D.: Am. J. Physiol. 151:239 (Dec.), 1947