Neurohumoral and metabolic response to exercise in water.

Atrial natriuretic peptide (ANP) stimulates lipid mobilization and lipid oxidation in humans. The mechanism appears to promote lipid mobilization during exercise. We tested the hypothesis that water immersion augments exercise-induced ANP release and that the change in ANP availability is associated with increased lipid mobilization and lipid oxidation. In an open randomized and cross-over fashion we studied 17 men (age 31+/-3.6 years; body mass index 24+/-1.7 kg/m(2); body fat 17+/-6.7%) on no medication. Subjects underwent two incremental exercise tests on a bicycle ergometer. One test was conducted on land and the other test during immersion in water up to the xiphoid process. In a subset (n=7), we obtained electromyography recordings in the left leg. We monitored gas exchange, blood pressure, and heart rate. In addition, we obtained blood samples towards the end of each exercise step to determine ANP, norepinephrine, epinephrine, lactate, free fatty acids, insulin, and glucose concentrations. Heart rate, systolic blood pressure, and oxygen consumption at the anaerobic threshold and during peak exercise were similar on land and with exercise in water. The respiratory quotient was mildly reduced when subjects exercised in water. Glucose and lactate measurements were decreased whereas free fatty acid concentrations were increased with exercise in water. Water immersion attenuated epinephrine and norepinephrine and augmented ANP release during exercise. Even though water immersion blunts exercise-induced sympathoadrenal activation, lipid mobilization and lipid oxidation rate are maintained or even improved. The response may be explained by augmented ANP release.

Determinants of exercise-induced fat oxidation in obese women and men.

Endurance training at an intensity eliciting maximal fat oxidation may have a beneficial effect on body weight and glucose metabolism in obese patients. However, the exercise intensity at which maximal fat oxidation occurs and the factors limiting fat oxidation are not well studied in this population. Obese, otherwise healthy men (n=38) and women (n=91) performed an incremental exercise test up to exhaustion on a cycle ergometer. Substrate oxidation was estimated using indirect calorimetry. Magnetic resonance tomography and spectroscopy were conducted to assess body fat distribution and intramyocellular fat content. We determined the exercise intensity at which maximal body fat oxidation occurs and assessed whether body composition, body fat distribution, intramyocellular fat content, or oxidative capacity predict exercise-induced fat oxidation. Maximal exercise-induced fat oxidation was 0.30+/-0.02 g/min in men and 0.23+/-0.01 g/min in women (p<0.05). Exercise intensity at the maximum fat oxidation was 42+/-2.2% VO (2 max) in men and 43+/-1.7% VO (2 max) in women. With multivariate analysis, exercise-induced fat oxidation was related to fat-free mass, percent fat mass, and oxidative capacity, but not to absolute fat mass, visceral fat, or intramyocellular fat content. We conclude that in obese subjects the capacity to oxidize fat during exercise appears to be limited by skeletal muscle mass and oxidative capacity rather than the availability of visceral or intramyocellular fat.

Tricyclic neuroleptic and antidepressant overdose: epidemiological, electrocardiographic, and clinical features--a survey of 92 cases.

From 1976 to 1980, there were 3,193 admissions due to acute drug overdosage at the resuscitation centre of the Rudolf-Virchow-Hospital, Free University of Berlin. The frequency and the characteristics of selfpoisoning with antidepressants and low-potency neuroleptic drugs (mainly perazine and thioridazine) were determined. These drugs were involved in 92 cases (3%) during this five-year period. Amitriptyline--in combination with a benzodiazepine--was the most common antidepressant taken by the patients. Ten of the patients required assisted ventilation. Complete ECG recordings were carried out in 24 patients. The most common abnormality was a prolonged QTc interval (21 patients) followed by a QRS duration of 0.11 seconds or longer (17 patients). Sinus tachycardia was present in half of the cases. In no cases did the medical records describe convulsions or cardiac arrhythmias requiring special treatment. The percentage of patients showing ECG changes and respiratory depression was higher when other drugs such as ethanol were ingested along with antidepressants than when only antidepressants were taken. One patient died after six weeks in hospital due to a complicated abscess. From 1976 to 1980, the incidence of antidepressant selfpoisoning was relatively low compared with findings from other studies. Data from other studies suggest that, in the period 1980-1987, there was an increase in the incidence of antidepressant selfpoisoning, at least in the West Berlin and Munich areas. However, these figures are much lower than those reported by British, American, and Australian authors.

Poisoning with antidepressive drugs: a five-year retrospective study.

From 1976 to 1980, there were 3,193 admissions due to acute drug overdosage at the Resuscitation Center of the Klinikum Charlottenburg of Berlin, Free University. We determined the frequency and characteristics of self-poisoning with antidepressants and some low potency neuroleptic drugs (perazine and thioridazine). These drugs were involved in 92 cases (i.e., 3%) during a 5-year period. Amitriptyline - in combination with a benzodiazepine - was the most common antidepressant taken by the patients. 10 of the patients required assisted ventilation. Complete ECG recordings were carried out in 24 patients; 21 of them had abnormalities comprising prolonged QTC and PR intervals (19, 15 and 8 patients, respectively). Sinus tachycardia was present in half of those patients. In no cases were convulsions or cardiac arrhythmias requiring special treatment described in the medical records. The percentage of patients showing ECG changes and respiratory depression was higher when other drugs such as ethanol were ingested along with antidepressants than when only antidepressants were taken. The incidence of antidepressant self-poisoning in this area was relatively low compared to the results of other studies. Possible explanations for its low frequency could be a low rate of prescription of antidepressants, a low dosage prescribed or the success of antidepressants in the treatment of depression and thereby in the prevention of attempted suicide.