Abstract
Based on animal experiments it has been proposed that antihypertensive agents may
differentially influence albuminuria through their divergent effects on glomerular
haemodynamics or glomerular sieving properties and may beneficially influence the
progression of diabetic nephropathy even without an effect on blood pressure. However,
to date this hypothesis has not been tested in normotensive patients with diabetic
nephropathy. The main aim of this study was therefore to investigate the effects of
the administration of two antihypertensive agents on albuminuria during rest and exerdse.
The study consisted of 3 × 3 randomised, cross-over periods with five days double
blind administration of enalapril (E: 2.5 mg bid), nitrendipine (N: 5 mg bid) and
placebo (P) on 18 Type 1 normotensive (blood pressure <140/90 mmHg) diabetic patients
with incipient diabetic nephropathy (albuminuria 30-300 mg/24 h, normal glomerular
filtration rate, diabetes duration > 6 years and presence of diabetic reinopathy.
The aim of this study was to investigate the effect of enalapril and nitrendipine
on blood pressure values and albuminuria during exercise challenge (bicycle ergometry:
20 min at 75 W and 20 min at 100 W) in comparison to the placebo. Albumin excretion
rates during pre-exercise rest (mean ± SD; E: 6.2 ± 6.0; N: 7.1 ± 8.0; P: 7.7 ± 7.0
mg/mmol creatinine) and during exercise (E: 8.7 ± 9.4; N: 8.2 ± 8.2; P: 11.1 ± 11.4
mg/mmol creatmine) were comparable between the drugs and not significantly different
after administration of placebo. Blood pressure values were significanatly different
between the medications (systolic blood pressure: p = 0.0269; diastolic blood pressure:
p = 0.0021, ANOVA for repeated measurements). There were no significant correlations
between blood pressure values and albuminuria at any time. In normotensive patients
with incipient diabetic nephropathy low-dose administration of enalapril, nitrendipine
and placebo does not result in clear cut differences in albuminuria.
Key words
Antihypertensive Agents - Nitrendipine - Enalapril - Diabetic Nephropathy - Microalbuminuria
