EFFECTS OF SODIUM STATUS ON THE VENOUS RESPONSE TO NORADRENALINE INFUSION IN PRE-ASCITIC CIRRHOSIS

1. This study assesses the effects of sodium status on venous responsi veness to noradrenaline and the neurohumoral profile in pre-ascitic ci rrhotic patients. Eight cirrhotic patients and ten control subjects we re studied after both a low (20 mmol/day) and a high (200 mmol/day) so dium diet. Venous responsiveness to increasing doses of noradrenaline in a dorsal hand vein and various plasma hormone levels were measured. Maximal response (R(max)) and the dose of noradrenaline that yielded 50% of R(max) (ED(50)) were then calculated. 2. A significantly smalle r dorsal hand vein diameter was observed in the control subjects on a low sodium (2.23+/-0.14 mm) compared with a high sodium (2.57+/-0.15 m m; P=0.04) diet, but not in the cirrhotic patients. R(max) was not sig nificantly different in either group on both diets. With low sodium in take, ED(50) was similar in the two groups. However, on high sodium in take, control subjects had a significantly higher ED(50) (34.4+/-7.4 n g/min) than the cirrhotic patients (5.03+/-0.86 ng/min; P<0.003). Plas ma noradrenaline in the control subjects fell significantly with the c hange from a low (1.29+/-0.11 nmol/l) to a high (0.68+/-0.09 nmol/l; P <0.001) sodium diet, but remained elevated in the cirrhotic patients. Cirrhotic patients had significantly higher atrial natriuretic factor levels and lower plasma renin activity than the control subjects on bo th diets. 3. In conclusion, pre-ascitic cirrhotic patients show no evi dence of venodilatation. Their sympathetic nervous activity is not sup pressible by volume expansion. Relative hyper-responsiveness of the pe ripheral venous circulation to adrenergic stimulation with high sodium intake is present.