Effect of aminophylline on urinary excretion of epinephrine and norepinephrine in man.

SUMMARY The excretion of catecholamines and the changes in plasma concentration of free fatty acids during aminophylline administration were explored. The relationships be tween cardiac arrhythmia, cardiac rate, and change in blood pressure under the conditions of these experiments were defined. Eighteen experiments were performed on eight volunteers. Blood pressures and heart rates before and during aminophylline infusion were recorded at frequent intervals, and urine and blood were collected during the control and infusion periods and in some subjects after the infusion. Loading with ethanol, glucose, or placebo before administration of aminophvlline was used. These studies demonstrated that intravenous infusion of aminophylline increases the urinary excretion of epinephrine and norepinephrine in man, the rate of excretion of epinephrine being greater than that of norepinephrine. This increase was accompanied by an increase in the concentration of free fatty acids in the plasma. Catecholamines I Blood pressure Glucose Autonom Diuresis Heart rate iic nervous system Ethanol Theophylline Blood lipids Arrhythmia D URING EXPERIMENTS originally designed to study free water clearance using ethanol and aminophylline, changes in cardiac rhythmicity and increased vasomotor activity were observed. This suggested an additional pharmacological effect of one or both of these drugs mediated through the sympathetic nervous system. Anton' has documented such an effect by ethanol. Cardiac arrhythmias, change in blood pressure, trem-ulousness, and sweating as well as sudden death2-4 during aminophylline administration have been linked to catecholamines only by inference.5 The present study was designed to explore further this relationship. Methods Eighteen experiments were performed on eight male volunteers ranging in age from 23 to 42 years. On the morning of the experiment, the subjects ate a light breakfast consisting of cereal and milk. Neither coffee nor cigarettes were allowed prior to or during the experiment. An in-dwelling forearm intravenous needle was kept patent by a slow (0.75 ml/min) infusion of 5% glucose in water throughout the experiment. After the initial urine was discarded, the subjects assumed a supine position and were given 500 to 1,000 ml of water orally, maintaining a positive water balance for the duration of the experiment. The blood pressures and heart rates before and during aminophylline infusion were recorded for 10 of the 12 studies at frequent intervals (2 to 5 min). The subjects voided at 15 to 30 minute intervals during the control (-60 to 0 min) and infusion (0 to 75 min) periods. In several subjects postinfusion (75 to …