Plasma dopamin-b-hydroxylase (DBH) was studied in 70 healthy control persons and in 37 hemodialysed patients. Basal DBH in controls corresponded to 50.0 +/- 29.3 IU. There was was no significant difference between males (53.9 +/1 33.8 IU) and females (47.4 +/- 25 IU); no correlation could be found between age and plasma DBH. In hemodialysed patients basal DBH levels were significantly (p less than 0.01) decreased (32.5 %/- 17.6 IU), suggesting lowered sympathetic activity and/or abnormalities in release, distribution space, or metabolism of DBH. During hemodialysis plasma DBH activity rose during ultrafiltration. This finding indicates a directionally appropriate sympathetic reflex response to volume depletion in dialysed patients.
Four different methods for the demonstration of the coronary arterial vasculature are examined. Among the techniques studied corrosion casts (epoxid- and acrylic resin) permit the best qualitative and quantitative evaluation of superficial and deep arteries and arterioles. Down to the smallest infusible vessels of 15-25 mum there is practically no shrinkage. X-ray arteriography with an aqueous solution of barium sulphate is less suitable because X-rays allow no satisfactory stereoscopic view. The demonstration of arterioles and collaterals is limited to vessels larger than 50 mum because of the low resolution of the X-ray tube. Silicone rubber does not only fill the arteries, but also the capillary bed and the venous system. Therefore deeper parts of the vasculature can only be studied after slicing the heart. The substantial shrinkage of the material makes quantitative measurements difficult.
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