[The effect of norfenefrine on circulation, plasma catecholamines and metabolism at rest and during exertion]

In a single-blind random cross-over study the influence of a Norfenefrin infusion (2-4 mg/kg per minute) on circulation, carbohydrate and fat metabolism, catecholamines, growth hormone, cortisol, and insulin was investigated. The investigations were carried out on 12 healthy male physical education students at rest and during physical exercise. Under Norfenefrin, heart rate was reduced at rest (-30%) and under low and medium work load (150 watts: -9%); under maximal work load heart rate remained unchanged. Systolic blood pressure at rest increased by 29%; the results under physical exercise differ only slightly, and during increased work load they did not differ significantly. Diastolic blood pressure, in contrast, increased at rest (+23%) and under submaximal (150 watts: +12%) and maximal work load (+12.5%). The product of systolic blood pressure and heart rate was significantly decreased at rest under Norfenefrin, whereas it tended to decrease only slightly during work load. Adrenaline remained unchanged, while noradrenaline had a tendency to decrease only slightly during submaximal work load and was significantly lower during maximal work load. Glucose, lactate, glycerol, free fatty acids, and triglycerides, as well as growth hormone, cortisol, and insulin, remained unchanged. The physical working capacity remained unaffected. These observations confirm the predominant alpha-receptor-stimulating effect of Norfenefrin. The decrease in noradrenaline during exercise indicates the ability of Norfenefrin to interfere with the autoregulation of transmitter release and to replace endogenous noradrenaline.