Effect of different flows during hypothermic cardiopulmonary bypass on open heart surgery on oxygen consumption and serum levels of lactate and pyruvate

This study was designed to investigate the effects of low flow versus high flow on hemodynamic variables, oxygen consumption and metabolic products in the form of lactate and pyruvate in thirty patients undergoing open heart surgery due to rheumatic heart disease. The results showed that hemodynamic parameters [central venous pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure and systolic and diastolic blood pressure] were not significantly different between the two studied groups in pre-and post bypass. During bypass, the mean arterial blood pressure was significantly higher in high flow rate group than the low flow rate group i.e. blood pressure was flow dependent. In both groups, the systemic vascular resistance was reduced post bypass than pre bypass and the cardiac output was significantly increased during post bypass than pre bypass period and no significant difference could be detected between the two studied groups

Comparison of effects of yoga & physical exercise in athletes.

The effect of pranayama a controlled breathing practice, on exercise tests was studied in athletes in two phases; sub-maximal and maximal exercise tests. At the end of phase I (one year) both the groups (control and experimental) achieved significantly higher work rate and reduction in oxygen consumption per unit work. There was a significant reduction in blood lactate and an increase in P/L ratio in the experimental group, at rest. At the end of phase II (two years), the oxygen consumption per unit work was found to be significantly reduced and the work rate significantly increased in the experimental group. Blood lactate decreased significantly at rest in the experimental group only. Pyruvate and pyruvate-lactate ratio increased significantly in both the groups after exercise and at rest in the experimental group. The results in both phases showed that the subjects who practised pranayama could achieve higher work rates with reduced oxygen consumption per unit work and without increase in blood lactate levels. The blood lactate levels were significantly low at rest.

Interaction of exercise and age on substrates of carbohydrate metabolism.

Changes in blood lactate, pyruvate, glucose and tissue glycogen were used as indices to evaluate the extent of effects of physical conditioning in young and old male rats. Rats were trained on a running wheel and swimming tank for 10 weeks. Biochemical estimations of lactic acid (LA) pyruvic acid (PA) and glucose (GL) in plasma and glycogen in cardiac and slow-twitch soleus (SOL) and fast-twitch extensor digitorum longus (EDL) skeletal muscles of trained animals were conducted and compared with those of sedentary control rats. Blood parameters showed a decrease upon training in both young and old rats, though of variable significances, between exercise types. Glycogen levels in the cardiac and skeletal muscles increased in all groups with the exception in SOL of older trained animals. Hepatic glycogen exhibited an insignificant increase in all groups. Results suggest that, though the trends of responses of both young and old rats to exercise follow a comparable path, the magnitudes of changes are definitely impressed upon appreciably by increasing age.

Effects of topically applied sulphur mustard on tissue glycogen, blood glucose, lactate and pyruvate in mice.

Bis-2-Chloroethyl sulphide, commonly known as sulphur mustard (SM) or mustard gas, an alkylating agent, is frequently used as a chemical warfare agent. Inhibition of glycolysis has been related to skin injury and cell death. The effects of SM on tissue glycogen, blood glucose, lactate/pyruvate ratio were investigated in the present study. After a single dermal application of 1.0 LD50 SM in mice, a significant hyperglycemia was observed at 24 hr post exposure. There was a corresponding decrease in liver glycogen content, with no alteration in glycogen content of brain, muscles and kidney. Blood pyruvate and lactate levels were not appreciably altered.

Role of epidural analgesia on endocrine & metabolic responses to surgery.

Serum levels of cortisol, T3, T4 and blood levels of glucose, lactate and pyruvate were measured 15 min before anaesthesia, 15 and 60 min after skin incision and at 2 h after surgery, in 16 patients undergoing elective surgery on lower extremities either under epidural analgesia (group I) or general anaesthesia (group II). The results showed that as long as the effect of epidural analgesia persisted, it could inhibit the increases in cortisol and blood glucose and the decreases in T3 levels, observed under general anaesthesia. This is probably because of the blocking effect of epidural analgesia on the afferent neurogenic impulses from the area of surgery. T4, lactate and pyruvate levels were not affected to any significant extent. These observations could be of value in the operative management of patients with diabetes mellitus and others with a high surgical morbidity.

Regulatory mechanisms of blood lactate production during exercise in man

During cycloergometric exercise at progressively increasing loads, blood lactate concentration increased about 12-fold. Pyruvate concentration decreased initially(for loads of 50-75 W), increased with loads of 75 to 125 W and then decreased again until the end of exercise. the malate concentration increased abruptly between 50 and 75 W, followed by a slow decline; citrate increased about nine-fold as the exercise load was increased to 125 W and then fell sharply. Thus, the production of lactate during low-intensity exercise seems to occur by the "mass-action effect" caused by enhanced glycolysis, whereas with moderate loads the glycolysis rate is very much reduced and most of the lactate production seems to involve the action of the malate-aspartate shuttle. For high-intensity exercise, both mechanisms appear to participate in lactate production

Blood ketoacids and its relation to respiratory quotient.

The total number of 43 young boys and girls of varying age group between 17-22 years were studied. The levels of blood ketoacids e.g., pyruvate and alphaketoglutarate were estimated spectrophotometrically. The RQ was determined by open circuit method of calorimetry by using Douglas bag for 13 boys and 13 girls and the BMR was estimated by closed circuit method of calorimetry using Collin's metabolex. With the increase of age the RQ and pyruvate were found to increase till the age of 20 years for both the sexes. The increased pyruvate level had a positive correlation with the age for the girls and the alphaketoglutaric acid had no such correlation with age for both the sexes.

Effect on mental stress on intermediate carbohydrate-and lipid-metabolism.

Changes in blood levels of Glucose, Pyruvic acid, Lactic acid, Glycogen, Free Fatty Acids and total Serum Cholesterol have been studied in normal healthy human adults under the effect of mental stresses of pre-examination tension and pre-operative apprehension. A highly significant rise in all the parameters was noted.