Influence of caffeine on metabolic responses of men at rest in 28 and 5 degrees C

1990 ◽  
Vol 68 (5) ◽  
pp. 1889-1895 ◽  
Author(s):  
K. W. MacNaughton ◽  
P. Sathasivam ◽  
A. L. Vallerand ◽  
T. E. Graham
Keyword(s):  
Cold Stress ◽  
Respiratory Exchange Ratio ◽  
Plasma Catecholamines ◽  
Plasma Norepinephrine ◽  
O2 Consumption ◽  
Plasma Epinephrine ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Adult Men ◽  
Norepinephrine Metabolism

Cold stress and caffeine ingestion are each reported to increase plasma catecholamines, free fatty acid (FFA) concentrations, and energy metabolism. This study examined the possible interaction of these two metabolic challenges in four double-blind counterbalanced trials. Young adult men (n = 6) ingested caffeine (5 mg/kg) or placebo (dextrose, 5 mg/kg) and rested for 2 h in 28 or 5 degrees C air. Cold stress alone elevated (P less than 0.05) plasma norepinephrine, metabolism (O2 consumption, VO2), and respiratory exchange ratio (RER). Caffeine alone increased (P less than 0.05) plasma epinephrine and FFA but not RER. When the two challenges were combined (caffeine plus 5 degrees C for 2 h) norepinephrine and epinephrine were increased (P less than 0.05) as was FFA. However, VO2, RER, and skin and rectal temperatures were not different from the responses observed at 5 degrees C after placebo ingestion. The data suggest that caffeine selectively increases plasma epinephrine, whereas cold air increases norepinephrine. During the cold exposure, increasing epinephrine and FFA above normal levels did not appear to influence the metabolic or thermal responses to the cold stress. In fact the increase in RER suggested a greater carbohydrate oxidation.

Influence of cold, exercise, and caffeine on catecholamines and metabolism in men

1991 ◽  
Vol 70 (5) ◽  
pp. 2052-2058 ◽  
Author(s):  
T. E. Graham ◽  
P. Sathasivam ◽  
K. W. MacNaughton
Keyword(s):  
Fatty Acids ◽  
Oxygen Consumption ◽  
Cold Stress ◽  
Free Fatty Acids ◽  
The Body ◽  
Plasma Norepinephrine ◽  
Plasma Epinephrine ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Cold Air

Recently we found that caffeine ingestion did not enhance either thermal or fat metabolic responses to resting in cold air, despite an increase in plasma epinephrine and free fatty acids. Theophylline, another methylxanthine, has been shown to be effective during exercise but not at rest during cold stress. Therefore we hypothesized that caffeine ingestion before exercise in cold air would have a thermal-metabolic impact by increasing fat metabolism and increasing oxygen consumption. Young adult men (n = 6) who did not normally have caffeine in their diet performed four double-blind trials. Thirty minutes after ingesting placebo (dextrose, 5 mg/kg) or caffeine (5 mg/kg) they either exercised (60 W) or rested for 2 h in 5 degrees C air. Cold increased (P less than 0.05) plasma norepinephrine while both caffeine and exercise increased (P less than 0.05) epinephrine. Serum free fatty acids and glycerol were increased, but there were no differences between rest and exercise or placebo and caffeine. Caffeine had no influence on either respiratory exchange ratio or oxygen consumption either at rest or during exercise. The exercise trials did not significantly warm the body, and they resulted in higher plasma norepinephrine concentrations and lower mean skin temperatures for the first 30 min. The data suggest that skin temperature stimulates plasma norepinephrine while caffeine has little effect. In contrast, caffeine and exercise stimulate plasma epinephrine while cold has minimal effect. Within the limits of this study caffeine gave no thermal or metabolic advantage during a cold stress.

Endurance run increases circulating IL-6 and IL-1ra but downregulates ex vivo TNF-alpha and IL-1 beta production

1995 ◽  
Vol 79 (5) ◽  
pp. 1497-1503 ◽  
Author(s):  
J. P. Drenth ◽  
S. H. Van Uum ◽  
M. Van Deuren ◽  
G. J. Pesman ◽  
J. Van der Ven-Jongekrijg ◽  
...  
Keyword(s):  
Vascular Resistance ◽  
Ex Vivo ◽  
Plasma Catecholamines ◽  
Plasma Norepinephrine ◽  
O2 Consumption ◽  
Esophageal Temperature ◽  
Trained Subjects ◽  
Norepinephrine Concentration ◽  
Fluid Losses ◽  
Cutaneous Vascular Resistance

This investigation determined the manner in which the cardiovascular system copes with the dehydration-induced reductions in cardiac output (Q) during prolonged exercise in the heat. On two separate occasions, seven endurance-trained subjects (maximal O2 consumption 4.70 +/- 0.41 l/min) cycled in the heat (35 degrees C) for 2 h, beginning at 62 +/- 2% maximal O2 consumption. During exercise, they randomly received either 0.2 liter of fluid and became dehydrated by 4.9 +/- 0.2% of their body weight [i.e., dehydration trial (DE)] or 3.6 +/- 0.4 liter of fluid and replaced 95% of fluid losses [i.e., euhydration trial (EU)]. During the 10- to 120-min period of EU, Q, mean arterial pressure (MAP), systemic vascular resistance (SVR), cutaneous vascular resistance (CVR), and plasma catecholamines did not change while esophageal temperature stabilized at 38.0 +/- 0.1 degrees C. Conversely, after 120 min of DE, Q and MAP were reduced 18 +/- 3 and 5 +/- 2%, respectively, compared with EU (P < 0.05). This was associated with a significantly higher SVR (17 +/- 6%) and plasma norepinephrine concentration (50 +/- 19%, P < 0.05). In addition, CVR was also significantly higher (126 +/- 16 vs. 102 +/- 6% of 20-min value; P < 0.05) during DE despite a 1.2 +/- 0.1 degrees C greater esophageal temperature (P < 0.05). In conclusion, significant reductions in Q are accompanied by significant increases in SVR and plasma norepinephrine and a slight although significant decline in MAP. The cutaneous circulation participates in this systemic vasoconstriction as indicated by increases in CVR despite significant hyperthermia.

Dehydration reduces cardiac output and increases systemic and cutaneous vascular resistance during exercise

1995 ◽  
Vol 79 (5) ◽  
pp. 1487-1496 ◽  
Author(s):  
J. Gonzalez-Alonso ◽  
R. Mora-Rodriguez ◽  
P. R. Below ◽  
E. F. Coyle
Keyword(s):  
Cardiac Output ◽  
Vascular Resistance ◽  
Plasma Catecholamines ◽  
Plasma Norepinephrine ◽  
O2 Consumption ◽  
Esophageal Temperature ◽  
Trained Subjects ◽  
Norepinephrine Concentration ◽  
Fluid Losses ◽  
Cutaneous Vascular Resistance

This investigation determined the manner in which the cardiovascular system copes with the dehydration-induced reductions in cardiac output (Q) during prolonged exercise in the heat. On two separate occasions, seven endurance-trained subjects (maximal O2 consumption 4.70 +/- 0.41 l/min) cycled in the heat (35 degrees C) for 2 h, beginning at 62 +/- 2% maximal O2 consumption. During exercise, they randomly received either 0.2 liter of fluid and became dehydrated by 4.9 +/- 0.2% of their body weight [i.e., dehydration trial (DE)] or 3.6 +/- 0.4 liter of fluid and replaced 95% of fluid losses [i.e., euhydration trial (EU)]. During the 10- to 120-min period of EU, Q, mean arterial pressure (MAP), systemic vascular resistance (SVR), cutaneous vascular resistance (CVR), and plasma catecholamines did not change while esophageal temperature stabilized at 38.0 +/- 0.1 degrees C. Conversely, after 120 min of DE, Q and MAP were reduced 18 +/- 3 and 5 +/- 2%, respectively, compared with EU (P < 0.05). This was associated with a significantly higher SVR (17 +/- 6%) and plasma norepinephrine concentration (50 +/- 19%, P < 0.05). In addition, CVR was also significantly higher (126 +/- 16 vs. 102 +/- 6% of 20-min value; P < 0.05) during DE despite a 1.2 +/- 0.1 degrees C greater esophageal temperature (P < 0.05). In conclusion, significant reductions in Q are accompanied by significant increases in SVR and plasma norepinephrine and a slight although significant decline in MAP. The cutaneous circulation participates in this systemic vasoconstriction as indicated by increases in CVR despite significant hyperthermia.

Effect of hypophysectomy on plasma catecholamines and enkephalins in fetal sheep

1993 ◽  
Vol 265 (2) ◽  
pp. E203-E209
Author(s):  
C. L. Coulter ◽  
I. R. Young ◽  
G. Simonetta ◽  
I. C. McMillen
Keyword(s):  
Gestational Age ◽  
Plasma Concentrations ◽  
Plasma Catecholamines ◽  
Plasma Norepinephrine ◽  
Plasma Epinephrine ◽  
Fetal Sheep ◽  
Fetal Plasma ◽  
Hypoxic Conditions

The aim of this study was to determine the effect of fetal hypophysectomy on the plasma concentrations of catecholamines and enkephalins in the fetal sheep between 120 and 140 days gestation under basal and hypoxic conditions. During basal conditions, there was no difference in the plasma concentrations of norepinephrine and epinephrine between intact and hypophysectomized groups. Fetal plasma norepinephrine concentrations were significantly increased during hypoxia in intact fetal sheep (7.2 +/- 2.2 pmol/ml, -15 min; 20.2 +/- 7.7 pmol/ml, 30 min) between 130 and 140 days, but after fetal hypophysectomy there was no significant norepinephrine response to hypoxia at this gestational age (4.7 +/- 1.3 pmol/ml, -15 min; 8.8 +/- 2.8 pmol/ml, 30 min). In contrast, fetal plasma epinephrine concentrations were significantly increased during hypoxia in both the intact (1.5 +/- 0.5 pmol/ml, -15 min; 3.3 +/- 1.7 pmol/ml, 30 min) and hypophysectomized groups (1.8 +/- 0.6 pmol/ml, -15 min; 6.8 +/- 4.1 pmol/ml, 30 min) between 130 and 140 days. During basal conditions, plasma concentrations of free Met-Enk were significantly less in hypophysectomized fetal sheep (170.8 +/- 34.3 pg/ml; 120-140 days) than in intact fetal sheep (305.6 +/- 47.3 pg/ml). There were no differences, however, in the fetal plasma concentrations of total Met-Enk between the intact (18.0 +/- 1.9 ng/ml) and hypophysectomized (16.9 +/- 2.6 ng/ml) groups. During hypoxia, there were no changes in the fetal plasma concentrations of either free or total Met-Enk in the intact or hypophysectomized groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Performance and metabolic responses to a high caffeine dose during prolonged exercise

1991 ◽  
Vol 71 (6) ◽  
pp. 2292-2298 ◽  
Author(s):  
T. E. Graham ◽  
L. L. Spriet
Keyword(s):  
Prolonged Exercise ◽  
Respiratory Exchange Ratio ◽  
Plasma Free Fatty Acid ◽  
Cycling Performance ◽  
Plasma Norepinephrine ◽  
Double Blind ◽  
Fatty Acid Data ◽  
Exercise Endurance ◽  
Trained Runners ◽  
Epinephrine Concentration

The present study examined whether a high caffeine dose improved running and cycling performance and altered substrate metabolism in well-trained runners. Seven trained competitive runners [maximal O2 uptake (VO2max) 72.6 +/- 1.5 ml.kg-1.min-1] completed four randomized and double-blind exercise trials at approximately 85% VO2max; two trials running to exhaustion and two trials cycling to exhaustion. Subjects ingested either placebo (PL, 9 mg/kg dextrose) or caffeine (CAF, 9 mg/kg) 1 h before exercise. Endurance times were increased (P less than 0.05) after CAF ingestion during running (PL 49.2 +/- 7.2 min, CAF 71.0 +/- 11.0 min) and cycling (PL 39.2 +/- 6.5 min, CAF 59.3 +/- 9.9 min). Plasma epinephrine concentration [EPI] was increased (P less than 0.05) with CAF before running (0.22 +/- 0.02 vs. 0.44 +/- 0.08 nM) and cycling (0.31 +/- 0.06 vs. 0.45 +/- 0.06 nM). CAF ingestion also increased [EPI] (P less than 0.05) during exercise; PL and CAF values at 15 min were 1.23 +/- 0.13 and 2.51 +/- 0.33 nM for running and 1.24 +/- 0.24 and 2.53 +/- 0.32 nM for cycling. Similar results were obtained at exhaustion. Plasma norepinephrine was unaffected by CAF at rest and during exercise. CAF ingestion also had no effect on respiratory exchange ratio or plasma free fatty acid data at rest or during exercise. Plasma glycerol was elevated (P less than 0.05) by CAF before exercise and at 15 min and exhaustion during running but only at exhaustion during cycling. Urinary [CAF] increased to 8.7 +/- 1.2 and 10.0 +/- 0.8 micrograms/ml after the running and cycling trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma catecholamines after thyrotropin-releasing hormone administration in hypothyroid patients before and during therapy

1994 ◽  
Vol 130 (3) ◽  
pp. 220-223 ◽  
Author(s):  
Antonino Velardo ◽  
Graziano Del Rio ◽  
Giuseppe Zizzo ◽  
Maria G Venneri ◽  
Luciano Della Casa ◽  
...  
Keyword(s):  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Plasma Catecholamines ◽  
Thyrotropin Releasing Hormone ◽  
Plasma Norepinephrine ◽  
Plasma Epinephrine ◽  
Releasing Hormone ◽  
Hormone Administration ◽  
Hypothyroid Patients

Velardo A, Del Rio G, Zizzo G, Venneri MG, Della Casa L, Marrama P. Plasma catecholamines after thyrotropin-releasing hormone administration in hypothyroid patients before and during therapy. Eur J Endocrinol 1994;130:220–3. ISSN 0804–4643 In order to investigate sympathoadrenal activity in hypothyroidism we studied the cardiovascular and catecholamine responses to thyrotropin-releasing hormone (TRH) infusion in nine hypothyroid patients before and during adequate therapy and in seven healthy subjects. We evaluated mean arterial pressure, heart rate, plasma epinephrine and norepinephrine levels after TRH administration (200 μg iv) in the three groups. Mean arterial pressure, heart rate and plasma epinephrine levels were not different in the three groups and did not change after TRH administration. Hypothyroid subjects showed increased plasma norepinephrine levels (1.48 ± 0.15 nmol/l), which were reduced after euthyroidism was reached (0.84 ± 0.11 nmol/l) (p < 0.01). An exaggerated response of norepinephrine to TRH was observed in hypothyroid patients before therapy (incremental peak (IP) = 0.59 ± 0.13 nmol/l) but not in hypothyroid patients during therapy (IP = 0.19 ± 0.02 nmol/l p < 0.02) or in the control group (IP = 0.15 ± 0.04 nmol/l; p < 0.05). This study indicated that TRH administration is able to influence the sympathetic activity during hypothyroidism in humans. A Velardo. Cattedra di Endocrinologia, Via del Pozzo 71, 41100 Modena, Italy

Metabolic and exercise endurance effects of coffee and caffeine ingestion

1998 ◽  
Vol 85 (3) ◽  
pp. 883-889 ◽  
Author(s):  
T. E. Graham ◽  
E. Hibbert ◽  
P. Sathasivam
Keyword(s):  
Young Adults ◽  
The Other ◽  
Plasma Epinephrine ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
The Subject ◽  
Exercise Endurance ◽  
The Impact

Caffeine (Caf) ingestion increases plasma epinephrine (Epi) and exercise endurance; these results are frequently transferred to coffee (Cof) consumption. We examined the impact of ingestion of the same dose of Caf in Cof or in water. Nine healthy, fit, young adults performed five trials after ingesting (double blind) either a capsule (Caf or placebo) with water or Cof (decaffeinated Cof, decaffeinated with Caf added, or regular Cof). In all three Caf trials, the Caf dose was 4.45 mg/kg body wt and the volume of liquid was 7.15 ml/kg. After 1 h of rest, the subject ran at 85% of maximal O2consumption until voluntary exhaustion (∼32 min in the placebo and decaffeinated Cof tests). In the three Caf trials, the plasma Caf and paraxanthine concentrations were very similar. After 1 h of rest, the plasma Epi was increased ( P < 0.05) by Caf ingestion, but the increase was greater ( P < 0.05) with Caf capsules than with Cof. During the exercise there were no differences in Epi among the three Caf trials, and the Epi values were all greater ( P < 0.05) than in the other tests. Endurance was only increased ( P < 0.05) in the Caf capsule trial; there were no differences among the other four tests. One cannot extrapolate the effects of Caf to Cof; there must be a component(s) of Cof that moderates the actions of Caf.

Blood collection and processing for measurement of catecholamines in exercising rats

1987 ◽  
Vol 63 (1) ◽  
pp. 418-420 ◽  
Author(s):  
W. W. Winder ◽  
H. T. Yang
Keyword(s):  
Intravenous Injection ◽  
Time Course ◽  
Plasma Catecholamines ◽  
Blood Collection ◽  
Plasma Norepinephrine ◽  
Plasma Epinephrine ◽  
Sprague Dawley ◽  
Blood Samples ◽  
Pentobarbital Anesthesia ◽  
Sprague Dawley Rats

We have studied the time course of the decline in plasma catecholamines in the postexercise period in rats. Male Sprague-Dawley rats were run on the treadmill for 5 min at 31 m/min up a 15% grade. At the end of the exercise the rats were quickly anesthetized by intravenous injection of pentobarbital. Blood samples were collected as soon as possible (average of 43 s), at 2 and 7 min postexercise. Plasma epinephrine decreased from 0.79 +/- 0.09 ng/ml to 0.51 +/- 0.05 after 2 min and to 0.35 +/- 0.09 after 7 min. Plasma norepinephrine decreased from 0.89 +/- 0.16 ng/ml to 0.61 +/- 0.05 after 2 min and to 0.50 +/- 0.07 after 7 min. We also studied the effect of time of centrifugation with respect to time of blood collection on plasma catecholamines. If blood samples were kept on ice no significant change in plasma epinephrine occurred over a period of 1 h. A small (14%) but significant decrease in norepinephrine was observed after 15 and 60 min. These studies emphasize the importance of collecting rat blood samples as quickly as possible after the end of exercise. Catecholamines decline very quickly in the rat after intravenous pentobarbital anesthesia.

Catecholamine-fuel interrelationships during exercise in fasting men

1980 ◽  
Vol 48 (1) ◽  
pp. 109-113 ◽  
Author(s):  
J. M. Pequignot ◽  
L. Peyrin ◽  
G. Peres
Keyword(s):  
Maximal Oxygen Consumption ◽  
Plasma Catecholamines ◽  
Plasma Free Fatty Acid ◽  
Work Load ◽  
Bicycle Ergometer ◽  
Plasma Norepinephrine ◽  
Plasma Catecholamine ◽  
Adrenergic Response ◽  
Response To Exercise

Adrenergic response to exercise and the relationships between plasma catecholamines and blood energetic substrates were studied in sedentary men after 15 h of fasting. Subjects pedaled a bicycle ergometer until exhaustion at a work load approximating 80% maximal oxygen consumption. Working ability was diminished by the fast (P less than 0.025). Resting plasma norepinephrine level was increased by fasting. During exercise plasma epinephrine (E) and norepinephrine (NE) concentrations were more elevated in fasting subjects than in fed subjects. Plasma catecholamine (CA) levels in fasting men correlated with blood glucose, blood lactate, and plasma glycerol concentrations. There was no significative correlation between CA and plasma free fatty acid (FFA) levels. The increased adrenergic activity in fasting subjects correlated with reduced endurance time. This study emphasizes the role of CA release, probably combined with other hormonal factors, in the mobilization of energy substrates during submaximal exercise.

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