Vasoactive hormones during hemodialysis with intermittent ultrafiltration

The correlations between actual blood volume (BV), blood pressure (BP), heart rate, and plasma levels of renin activity (PRA), serum aldosterone (ALD), antidiuretic hormone (ADH), epinephrine (E), norepinephrine (NE), atrial natriuretic factor (ANF), cGMP, and cAMP were investigated in 10 stable patients during HD. HD consisted of four periods of about 60 min each. One half with an UF rate greater than 1,000 ml/h, followed by a time interval of 30 min without UF resulting in a "saw tooth" profile of BV. Decrease in BV was measured by continuous hemoglobinometry. Average total decrease in BV was 25%, while BP and HR did not change significantly. E, NE, ANF and ADH levels were directly related to actual changes in BV, suggesting that BP regulation in this special mode of HD is mainly supported by endogenous catecholamine and ADH secretion. The second messenger cGMP did not follow actual BV changes, but showed a significant decrease correlated with diminished BV. A significant change in PRA and ALD was missing. It is concluded that vascular stability in these patients is maintained by the response of catecholamins and ADH to decrease in blood volume, and not by the renin-aldosterone system.