ATRIAL-NATRIURETIC-PEPTIDE IN PATIENTS WITH DIABETES-MELLITUS TYPE-I - EFFECTS ON SYSTEMIC AND RENAL HEMODYNAMICS AND RENAL EXCRETORY FUNCTION

In the present study the effects of 1 h intravenous infusion of α-human atrial natriuretic peptide (24 ng/min/kg) on systemic and renal hemodynamics and on renal excretory function were studied in six insulin-treated and metabolically well-controlled patients with diabetes mellitus (DM) type I and in six healthy control subjects (C). Basal plasma atrial natriuretic peptide (ANP) concentration was 14.6 ± 2.0 in DM patients and 14.9 ± 1.3 pmol/L in C and rose similarly in both groups to 87.1 ± 22.1 and to 86.9 ± 11.1 pmol/L, respectively, during α-hANP infusion (P <. 05). Maximal effects of α-hANP occurred between 30 and 60 min after the start of the infusion. Mean arterial pressure (MAP) (83 ± 5 v 81 ± 3 mm Hg), heart rate (HR) (63 ± 2 v 64 ± 4/min) and total peripheral resistance (TPR) (11 ± 1 v 10 ± 1 mm Hg · min/L) remained unaltered in patients with DM. In contrast, in C MAP and TPR decreased from 83 ± 3 to 77 ± 2 mm Hg and from 12 ± 1 to 10 ± 1 mm Hg · min/L, respectively (P <. 05), whereas HR increased from 53 ± 2 to 59 ± 3 beats/min (P <. 05). Cardiac output (CO) rose initially by 11% and by 9% in DM and C, respectively. Urine flow increased from 4.1 ± 0.9 to 11.3 ± 1.5 mL/min in DM patients and from 3.9 ± 1.0 to 8.4 ± 0.8 mL/min in C (P <. 05). The rise in urinary sodium excretion from 251 ± 33 to 864 ± 98 μmol/min in DM was significantly more pronounced than that from 211 ± 37 to 451 ± 84 //mol/min in C. The increase in inulin clearance, a measure of glomerular filtration rate (GFR), from 119 ± 8 to 174 ± 13 mL/min/1.73 m2in patients with DM was also significantly (P < 0.05) greater than that from 108 ± 5 to 139 ± 12 mL/min/1.73 m2in C. Effective renal plasma flow (ERPF), determined as paraaminohip-purate clearance, increased from 688 ± 51 to 821 ± 79 mL/min/1.73 m2(P <. 05) in patients with DM but remained unaltered in C (587 ±17 v 567 ± 38 mL/min/1.73 m2). Filtration fraction (FF) rose by 26% and 31% in DM and C, respectively. Thus, infusion of α-hANP resulted in significantly greater increases in GFR and urinary sodium excretion in patients with DM than in C. A significant rise in ERPF occurred only in patients with DM, which, in addition to the rise in GFR, may be responsible for the enhanced natriuresis observed in these patients. The renal vasculature appears to be more sensitive to circulating ANP in patients with DM type I than in healthy subjects. © 1990 by the American Journal of Hypertension, Ltd.