On the pathogenesis of arterial blood pressure elevation early in the course of diabetic nephropathy

Abstract

We measured plasma- and extracellular fluid volume (¹²⁵I-albumin, ⁵¹Cr-EDTA), plasma concentrations of renin, angiotensin I and II, aldosterone and atrial natriuretic peptide by radio-immunoassays in insulin-dependent diabetic (IDDM) patients with (n=28) and without (n=ll) nephropathy and in 14 normal control subjects matched for sex and age. Glomerular filtration rate (GFR) (ml/min/1.73 m², single intravenous bolus ⁵¹Cr-EDTA technique) was within normal range in all nephropathy patients; 107 (range 78-134). Mean arterial blood pressure (mmHg) was elevated 102±13 (±S.D.) compared to the diabetic and normal control group, 92±8 and 87±5, respectively (p<0.01). Plasma volume was identical in all three groups while extracellular volume (1/1.73 m²) was expanded in nephropathic patients, 14.5±1.5 vs 13.1±0.9 and 12.4± 1.3 in the diabetic and non-diabetic control groups, respectively (p<0.05). A significant correlation between extracellular fluid volume and mean arterial blood pressure was found (n=53, r=0.49, p<0.001). Active renin was signficantly increased in patients with diabetic nephropathy compared with the normal control subjects, while all the remaining hormones were about the same in the three groups. Our study suggests that fluid retention plays a dominant role in the initiation and maintenance of arterial blood pressure elevation early in the course of diabetic nephropathy.

Key Words:

• arterial hypertension
• atrial natriuretic peptide
• diabetic nephropathy
• extracellular fluid volume
• insulin-dependent diabetes
• plasma volume
• renin-angiotensin-aldosterone system