No abstract

Noradrenaline and adrenaline were determined in blood samples from the brachial vein, the brachial artery, the left renal vein and the femoral vein in 6 healthy males (aged 23-35 y). In 3 of the subjects catecholamines were determined also in blood from the coronary sinus. All samples were taken simultaneously in supine postion after 30 min of rest and then in connection with exercise in supine position using a bicycle ergometer, firstly with a work load of 50 W for 9 min and secondly with a work load of 150 W for the same period of time. Under resting conditions the catecholamine levels were about the same at all locations, the mean for noradrenaline being 1.59 nmol/1 with a range of 1.30-2.11 nmol/1 and for adrenaline 0.46 nmol/1 and 0.23-0.65 nmol/1, respectively. At 50 W the noradrenaline concentration increased significantly in the brachial artery, the left renal vein and the femoral vein, whereas adrenaline increased significantly only in the femoral vein. At 150 W the noradrenaline content increased markedly in all samples, especially in the left renal vein (mean increase 13.02 nmol/1) and the coronary sinus (mean increase 13.06 nmol/1). Adrenaline concentration increased significantly in the brachial artery and the femoral vein. At 150 W the mean net output of noradrenaline as estimated from the calculated flows and actual AV-differences amounted to 2.25 nmol/min from the heart and to 0.36 nmol/min from the kidney.

The use of venous plasma noradrenaline levels as a marker of general sympathetic tone has been questioned as changes in local sympathetic activity may influence the venous levels. To compare arterial and venous plasma noradrenaline levels in patients with primary hypothyroidism, arterial and venous blood were sampled during strictly standardized conditions during hypothyroid and euthyroid states. The patients were hospitalized for 5 days at a metabolic ward on a standardized sodium and potassium intake. On the fourth day catheters were positioned in the axillary artery and vein. Blood samples were drawn simultaneously for noradrenaline and adrenaline determinations during resting conditions. The arterial and venous plasma noradrenaline levels did not differ significantly, neither during hypothyroidism nor during euthyroidism. The arteriovenous difference in plasma adrenaline was similar during hypothyroidism compared to euthyroidism, indicating similar peripheral extraction rate of catecholamines during hypothyroidism as compared to euthyroidism. During hypothyroidism venous and arterial noradrenaline were significantly higher as compared to euthyroidism. In conclusion, there is no difference between arterial and venous noradrenaline levels either in the hypothyroid or the euthyroid state, and the peripheral extraction rate of plasma noradrenaline seems to be similar in hypothyroidism and euthyroidism. The local contribution of noradrenaline from the arm, reflecting local sympathetic nervous activity, is limited during resting conditions. In hypothyroid patients plasma noradrenaline levels are increased as compared to the euthyroid state, indicating increased general sympathetic activity in hypothyroidism.

The volume of trapped gas (VTG) was measured at the end of a nitrogen multiple breath wash out procedure in 16 asthmatic and 10 healthy children before and after exercise. When compared to conventional spirometric variables VTG was the most sensitive test for detection of exercise-induced asthma (EIA). The VTG was significantly higher before exercise in the asthmatic children and increased significantly after exercise, while it did not change in the healthy controls. The significance of changes caused by EIA increased if VTG/TLC % or VTG/VC % wer used. Salbutamol inhalation normalized the VTG in all the asthmatic children.

The influence of body position on exercise tolerance, heart rate, systolic blood pressure, and breathing frequency was studied during bicycle exercise in 37 male patients with coronary insufficiency. With identical work loads before the onset of angina pectoris, the heart rate was significantly higher in the supine position. Exercise tolerance was lower in the supine position, and angina pectoris developed at a significantly lower heart rate and systolic blood pressure.