Controversy exists concerning the role that dopamine plays in analgesia. In the present studies, dopamine agonists produced analgesia, and D-amphetamine potentiated morphine analgesia, while treatment with 6-hydroxydopamine or mixed or selective D1 and D2 dopamine receptor antagonists attenuated or abolished morphine and D-amphetamine-induced analgesia, in the formalin test. Furthermore, microinjection of morphine into the ventral tegmental area (VTA) and ventral striatum produced analgesia, while intra-VTA microinjection of naloxone methylbromide antagonized the analgesia produced by systemic morphine, in the formalin test. In contrast, similar manipulations of dopamine had little or no effect in the tail flick test. Thus, dopamine appears to play a facilitatory role in formalin test analgesia, and there appear to be fundamental differences between the formalin and tail flick tests and parallels between the role of dopamine in the formalin test and in clinical pain, the vocalization after-discharge test and reward.

While a great deal of research has been directed towards the phenomena of excess post exercise oxygen consumption (EPOC), the effect of thermal stress on EPOC is not well defined. To assess the effect of heat stress on EPOC, seven healthy, active subjects (4 female, 3 male; 23.9 ± 2.0 years of age) performed 4 trials: one control (quiet rest) and one exercise (45 minutes of cycling at 65% VO2max workload) trial in moderate (23° C, 50% humidity) and hot (35° C, 50% humidity) environments. Oxygen consumption (V02), heart rate (HR) and rectal temperature (RT) were assessed pre, during and post control or exercise. Subjects were monitored until post exercise VO2 had returned to within ±2% of baseline. EPOC was determined by subtracting baseline VO2 from total V02 during the post exercise period. During the first 15 minutes (acute) post exercise, a significant EPOC (p = 0.0019) was seen in both exercise conditions over both control conditions. During the slow phase (> 15 minutes post exercise to baseline), there was no significant difference between the hot control (HC), moderate exercise (ME), or hot exercise (HE) EPOC. Total time post exercise until baseline was achieved was 35, 44, and 51 minutes for HC, ME, and HE respectively. HR was significantly elevated in both exercise conditions. During the acute post exercise period, HR in HE was elevated above MC, ME and HC (p < 0.05). RT was elevated in both exercise conditions during and post exercise. The present data indicate that heat stress does not have a significant effect on the magnitude or duration of EPOC. / School of Physical Education

Eight well-trained male and female cyclists were studied to determine the effect of sodium and/or water intake on plasma aldosterone during six hours of cycling (55% VO2max) in a warm environment (Tdb = 350C WBGT = 30°C). Each subject randomly completed three trials (water = W; saline = S and no fluid = NF) at one week intervals. Venous blood samples were obtained before dehydration, at 2, 4, 5 and 6 hours during exercise, and also after dehydration. Plasma samples were analyzed for hemoglobin, sodium, potassium, aldosterone and osmolality. Sweat and urine samples were also collected and analyzed for sodium content. Plasma volume based on hemoglobin decreased significantly ( P < 0.01 ) at 15 min in all three trials (Trial W = -7.6%±1.12%; Trial S = -8.6%±1.42% and Trial NF = -6.7%±0.88%) and continued to decrease significantly in Trial NF during exercise ( -10.99% ± 1.3% at the 2th hr; -15.5% ±1.3% at the 4th hr and -16.8%±1.32% at the 5th hr).No significant differences were found betwee trials. Plasma sodium concentration [Na+] decreased over time in Trials W and S and increased in Trial NF due to plasma volume loss. Significant differences in [ Na+ ] were found between Trial NF and Trials W or S. Plasma sodium [Na+ ] adjusted by plasma volume change decreased significantly at 2 hours ( P < 0.01) in the three trials. Average total sodium content of plasma decreased by 125.9 mEq during Trial S, 223.1 mEq during Trial W and 147.1 mEq during Trial NF. Plasma potassium increased significantly (P < 0.01) at 2 hours in all three trials. Plasma osmolality increased significantly (P < 0.01) during prolonged exercise (Trial W = 287.1±2.4 mEq/l; Trial S = 289.4±1.17 mEq/1 and Trial NF = 306±1.6 mEq/1). No significant differences were found between Trials W and S although osmolality was lower in Trial W than in Trial S. A significant difference in osmolality was obtained between Trial NF and Trials W and S (P < 0.01). Plasma aldosterone increased significantly (P < 0.01) during exercise and decreased after exercise. No significant differences existed between Trials W and S although aldosterone levels were lower in Trial S than in Trial W. However, a significant difference was found between Trial NF and Trials W or S. The results of this study suggest that plasma aldosterone has an inverse relationship with plasma volume changes and total sodium concentrations. An increase in plasma potassium and a decrease in plasma sodium during prolonged exercise in a warm environment significantly enhanced plasma aldosterone concentration. The intake of water significantly decreased plasma aldosterone during prolonged exercise in a warm environment, but the intake of sodium had no significant effect in this study. / School of Physical Education

The influence of caffeine on the metabolic and catecholamine responses to mild exercise in a cold and a warm environment was studied in eight healthy males. The subjects performed 60 minutes of cycling at 50% VO2max in a cold environment (5°C and 70% relative humidity) and a warm environment (28°C and 50% relative humidity) 30 minutes after ingesting caffeine (5mg/kg body weight) or placebo (dextrose). Caffeine ingestion prior to exercise in the warm environment resulted in increased plasma epinephrine, with no effect on plasma norepinephrine. Neither lipid nor carbohydrate metabolism was altered by caffeine in the warm trial. Exercise in the cold environment (placebo) produced increased oxygen consumption and carbohydrate metabolism, decreased lipid metabolism, and no difference in plasma catecholamines compared with the warm-placebo trial. Responses to the combination of caffeine ingestion and the cold environment did not differ from cold-placebo responses in oxygen consumption or respiratory exchange ratio during the cycling bout. However, in the cold-caffeine trial plasma epinephrine was elevated. In addition, fat oxidation, serum free fatty acids, and serum glycerol were elevated in the cold-caffeine condition. Carbohydrate oxidation was depressed, while serum glucose and blood lactate were elevated in this trial. The results of this study indicate that caffeine increases plasma epinephrine; cold increases oxygen consumption and carbohydrate metabolism, while decreasing lipid metabolism; and the combination of caffeine and cold during exercise increases plasma epinephrine and lipid metabolism, but decreases carbohydrate metabolism. / Human Performance Laboratory

In order to test the effect of artificially induced alkalosis and acidosis on the appearance of blood lactate and work production, six well-trained oarsmen (age= 23.8 ±2.5 wt = 82.0 ±7.5kg.) were tested on three separate occasions after ingestion of 0.3 gm/kg body wt. NH4C1 (acidosis) , NaHC03 (alkalosis) or a placebo (control). Blood was taken from a forearm vein immediately prior to exercise for determination of pH and bicarbonate (HC03). One hour following the ingestion period, subjects rowed on a stationary ergometer at a pre-determined sub-maximal rate for 4 minutes, then underwent an immediate transition to a maximal effort for 2 minutes. Blood samples from an indwelling catheter placed in the cephalic vein were taken at rest and every 30 seconds throughout the 6 minute exercise test, and every 3 minutes during a 30 minute passive recovery period. Pre-exercise blood values demonstrated significant differences (p<0.01) in pH and HC03 in all three conditions. Work outputs were unchanged in the submaximal test and in the maximal test (p>0.05), although a trend toward decreased production was evident in the acidotic condition. Analysis of exercise blood samples using ANOVA with repeated measures revealed that the linear increase in blood lactate concentration([BLA]) during control was significantly greater than acidosis (p<0.01), although [BLa] during alkalosis were consistently elevated above control there was no significant difference in the linear trend (p>0.05). During recovery, there was no significant difference in the rate of lactate disappearance amongst the three conditions. It was concluded that under this protocol artificial manipulation of the acid-base status of the blood does not significantly influence work production despite significantly reduced [BLa] during acidosis. The inability of these pH changes to alter exercise performance emphasizes the relative importance of the intracellular and the extracellular buffer systems in well trained athletes. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

The purpose of this study was to assess the energy demands of a 2,000 meter race simulation (RS) for national level oarswomen; as evaluated on a rowing ergometer (RE). A Progressive Intensity Test (P.I.T.) was also performed on the RE to further evaluate the RS. Six national level oarswomen (X values: age= 24.5 yrs., ht= 179 cm, wt= 75 kg), all current national team candidates (1988), participated in this investigation. A 6 1/2 minute tape recorded water race was used to execute a 2,000 meter RS on a Dr. Gjessing Ergorow ergometer. The tape recording was an actual race tape that was respliced to last exactly 6 1/2 minutes. Metabolic and respiratory exchange variables were continuously monitored by an open circuit method, utilizing a Beckman Metabolic Measurement Cart interfaced on-line with a Hewlitt Packard 3052A data acquisition system. The energy demands were calculated from metabolic variables, total oxygen cost and the analysis of excess post-exercise oxygen consumption (recovery V0₂).Results indicated a mean V0₂max. of 3.85 1.min⁻¹ , mean net V0₂ of 24.48 1 and a mean recovery V0₂ of 4.92 1. This represented the aerobic cost of the event at approximately 80% or 4/5ths of the total energy cost while the anaerobic contribution was approximately 20% of l/5th of the total energy cost. During the RS, V0₂ values rapidly increased to 90% of mean V0₂max. (3.85 l.min⁻¹) in the first two minutes. Mean max. VE (BTPS) RS value was 122.4 1.min⁻¹. VE plateaued after two minutes and remained around 90% of P.I.T. mean max. VE for the final 4 1/2 minutes. Mean max. excess C0₂ for RS was 19.81 ml.kg⁻¹.min⁻¹. The average maximal heart rate, as recorded in the RS was 192.8 bpm. The results of this study indicate the high aerobic demands and tremendous exercise intensity involved in the 2,000 meter RS. / Education, Faculty of / Curriculum and Pedagogy (EDCP), Department of / Graduate

The purpose of this investigation was to determine the effects of post-exercise carbohydrate-protein feedings on muscle glycogen restoration following exhaustive cycle ergometer exercise. Seven male collegiate cyclist (age=25.6±3.3y, ht.=180.9±8.5cm, wt.=75.4±10.7kg, VO2max=4.20±0.4 1•miri 1) performed three trials, each separated by -lwk, 1) 100% (x-D glucose (CHO), 2) 70% carbohydrate-20% protein-10% fat (CHOPRO), and 3) 86% carbohdyrate-14% amino acid (CHO-AA). All feedings were eucaloric, based upon 1.0 g•kgb.W.'1•hr"1 of carbohydrate, and administered every half hour during a four hour muscle glycogen restoration period in an 18% wt./vol. solution. Muscle biopsies were obtained immediately and four hours post exercise. Following the exhaustive exercise and every half hour for four hours a blood sample was drawn. Muscle glycogen concentrations increased 53%, 47%, and 57% for the CHO, CHO-PRO, and CHO-AA feedings, respectively, however no differences among the feedings were apparent in muscle glycogen restoration. The plasma glucose and insulin concentrations demonstrated no differences throughout the restoration period among the three feedings. These results suggest that muscle glycogen restoration does not appear to be enhanced with the addition of either protein or amino acids to an eucaloric carbohydrate feeding following an exhaustive cycle exercise. However, it appears that if adequate amounts of carbohydrates are consumed (greater than 0.70 g•kgb,W,."'•hf' carbohydrate) following exhaustive exercise, maximal muscle glycogen restoration occurs. / School of Physical Education

published_or_final_version / Biochemistry / Master / Master of Science

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