Hypertension and progression of renal insufficiency

Besides defining the appropriate doses of frusemide in uraemic patients, A. Heidland's contribution to the treatment of hypertension in chronic renal failure consisted in the following demonstrations: (1) In patients on chronic haemodialysis, calcium antagonists have a beneficial effect on their glucose intolerance and decreased plasma levels of 25OH vitamin D while their effect on blood lipids is neutral. (2) In 5/6 nephrectomized rats, captopril, verapamil, and metoprolol have the same protective effect on their GFR and tubular secretion of protons, at equal blood-pressure-lowering effect. (3) In rats with streptozotocin-induced diabetes, atrial natriuretic peptide does not play a role in their hyperfiltration. (4) Severe retinopathy is observed in patients with uraemic nephropathies at a much smaller elevation of their blood pressure than in patients with essential hypertension. This article reviews the following points: (1) The role of hypertension in the loss of renal function is convincingly demonstrated only in a few experimental models, and in man only in malignant hypertension and diabetic nephropathy but not in essential hypertension nor in non-diabetic nephropathy. However, preliminary results suggests that antihypertensive treatment may retard the progression of renal disease in normotensive patients (DBP <90 mmHg) with either microalbuminuric diabetes and normal renal function or non-diabetic uraemic nephropathy. (2) Only the ACE inhibitors have been proved to have a specific renal protective effect, independent of their diurnal blood-pressure-lowering effect, both in diabetic nephropathy and in non-diabetic uraemic nephropathy.