Renal response to central volume expansion induced by water immersion (WI) in heart transplant patients.

This work was aimed to assess the secretion of volume related hormones in heart transplant patients (HTP) and their relationship to excretory renal function studied under bed rest and water immersion conditions. Fractional sodium (FENa%) and potassium (FEK%) clearance, plasma renin activity (PRA), plasma aldosterone (Ald), vasopressin (AVP) and atrial natriuretic peptide (ANP) were estimated in six HTP with moderate renal failure (C creat = 69 +/- 6.9 ml/min) and in 10 healthy subjects (N) (C creat = 110 +/- 2.0 ml/min). All HTP were treated with cyclosporine A and azathioprine. In HTP basal AVP (6.18 +/- 0.92 pg/ml) and ANP (138.17 +/- 14.69 pg/ml) levels were significantly higher than in normals (2.07 +/- 0.11 pg/ml and 74.10 +/- 7.10 pg/ml, respectively). HTP were also characterized by increased FENa% and FEK% both under bed rest (DI) and water immersion (WI) conditions. As abnormalities of excretory renal function in HTP were not significantly related to the plasma endocrine profiles factors other than PRA, Ald, AVP and ANP seemed to be also involved in their pathogenesis.