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Biomedical subjects

T E Graham

Publications and source records attributed to T E Graham.

97 records · Page 6Linked to original sources
PubMed1982

The effects of hypercapnia on the metabolic response to steady-state exercise.

Studies on isolated muscle and resting man have demonstrated that altering CO2 stores influences intracellular lactate production and/or tissue lactate release. In the present project, subjects (N = 6) performed steady-state exercise for 30 min while inspiring 0, 2, 4, or 6% CO2 and 21% O2. They were tested on eight occasions, four at 50% and four at 65% VO2max. Arterialized venous blood PCO2 increased in proportion to FICO2 (P less than 0.05). Blood pH had a similar but inverse relationship, decreasing from 7.371 to 7.233 (P less than 0.05). The VI increased directly with PCO2 (P less than 0.05), but no differences were found for VO2 or VO2. The R decreased in proportion to PCO2 (P less than 0.05) at both exercise intensities. Blood lactate was reduced (P less than 0.05) with CO2. At 65% VO2max lactate had an inverse linear relationship with blood PCO2 (P less than 0.05). The mean lactate decreased 43% from 3.88 mM . l-1 with 0% CO2 to 2.22 mM . l-1 with 6% CO2. The R shift suggest that carbohydrate metabolism may have been inhibited and lipid metabolism enhanced.

Acidosis, Respiratory↗
PubMed1981

Medium for the accumulation of extracellular hemolysin and protease by Aeromonas hydrophila.

A medium for the accumulation of extracellular hemolysin (300 to 1,600 hemolytic units per ml) and protease (2 to 3 proteolytic units per ml) was developed for an anaerogenic strain of Aeromonas hydrophila. In this medium, growth yields were less but levels of accumulated toxin were greater or equivalent when compared with the same responses in brain heart infusion and nutrient broths. The medium was considered to be partially defined since the conditions for maximum observed hemolysin accumulation (1,600 hemolysin units per ml) were not identified. The results showed that iron and zinc contributed to the control of the extracellular accumulation of both toxins. Whereas iron exerted an inhibitory effect, zinc stimulated the accumulation of both toxins.

Aeromonas↗
PubMed1981

Thermal and glycemic responses during mild exercise in +5 to -15 degrees C environments following alcohol ingestion.

Male volunteers (3 groups of 6) were tested once after drinking alcohol (alc) and once after consuming a placebo. The subject drank 2.5 ml of 40% alc/kg in 30 min and, wearing a sweat suit, entered an environmental chamber (+5 degrees, -5 degrees, or -15 degrees C; one group at each temperature). Intermittent, bicycle exercise was performed for 3 h (40% VO2 max, 20 min work--10 min rest repeated 6 times). Peak blood alc (11.87 +/- 0.82 mM/occurred at 87.4 +/- 7.5 min; there were no differences between the three temperature groups. Based on pulmonary VO2 and RQ, neither environmental temperature nor alcohol affected metabolism, but blood glucose was significantly (p less than 0.05) lower with alcohol from 105 min until the end of the 3 h. Mean body temp was lower (p less than 0.05) in the -15 degrees C group and alcohol resulted in lower (p less than 0.05) body temperature in all three groups for the first 2 h. However, subjects did not perceive the increased heat loss or lower body temperatures. In contrast to cold water immersion studies, alcohol ingestion followed by mild exercise in a cold air environment results in enhanced heat loss and lower blood glucose levels.

Blood Glucose↗
PubMed1976

Metabolic intermediates and lactate diffusion in active dog skeletal muscle.

The concentration of several metabolic intermediates, blood flow (Q), oxygen uptake (VO2), and lactate release (La) were measured in the gastrocnemius muscle of anesthetized dogs. Muscle lactate concentration increased from 1.6 to 2.7 mumol/g wet wt (P less than 0.05) during 0.5-5 min of contractions at 5 twitches/s but was not different from the contralateral resting muscle at 15, 30, or 60 min. Glycerophosphate increased from 0.35 to 0.70 mumol/g wet wt (P less than 0.05) during 0.5-5 min of activity, whereas muscle pyruvate decreased from 0.09 to 0.07 mumol/g wet wt (P less than 0.05). The concentration of NAD did not change in 9 of 11 experiments during contractions, despite a 12- to 15-fold increase in La. Significant decreases in NAD were observed when Q was compromised by arterial occlusion during contractions. No demonstrable relationship existed between La and either the muscle lactate concentration or muscle-venous lactate concentration gradient. Q was positively correlated with both La and muscle lactate during the first 5-15 min of activity. We conclude that increased La or increased lactate concentration in muscle need not be associated with hypoxia and that Q has a major influence on La.

Animals↗
PubMedDate not supplied

Active skeletal muscle metabolism and tension production: the influence of biopsies.

The influence of repeated sampling by the biopsy technique on skeletal muscle's metabolic and force-output responses was studied using the in situ canine gastrocnemius preparation. The left muscle was stimulated (8 V, 0.2 ms) for 1 h at 3 Hz. In the biopsy series (n = 9) muscle samples were taken at rest, and at 0.5, 2, 5, 15, 30, 45, and 60 min of stimulation. In the control series (n = 8) the left and right muscles were quick-frozen in N2 immediately after the 60 min of stimulation. The two series were not different in blood flow, VO2, arterial or venous [H+], muscle glycogen, or lactate release throughout the 60 min of activity. The lactate release was transient and was associated with an accumulation of intramuscular lactate and a period of rapid glycogenolysis. The biopsy series had a modest but significantly (p < 0.05) higher muscle lactate concentration both at rest and at the end of the contractions. The biopsy series also had less (p < 0.05) tension development throughout the hour; however, the O2 cost per unit of tension development was not different between groups, nor was the rate of tension decline over time different. This together with the similarities in perfusion, carbohydrate use, and lactate metabolism suggests that repeated biopsies had minimal impact on the muscle. The technique allows the collection of data over time; this improves the detail of experiments and means that fewer animals are required for a study.

Animals↗