Recovery of erythrocyte Na(+)-K(+)-Cl- cotransport activity by enalapril.

We studied total exchangeable sodium, ion transport activity at maximal rate, and erythrocyte Na+ content in response to angiotensin converting enzyme inhibition in mild-to-moderate essential hypertensive patients with normal renal function. Twenty-five patients (mean age 56 years, range 40-62 years) who had abnormal red blood cell Na(+)-K(+)-Cl- cotransport or red blood cell Li(+)-Na+ countertransport were treated with either enalapril (20 mg daily) or hydrochlorothiazide (50 mg daily) during a 30-day period. During the period of enalapril treatment, Na(+)-K+ pump and Na(+)-K(+)-Cl- cotransport increased significantly from 4,282 +/- 255 to 5,236 +/- 325 mumol/l red blood cell/hr (p less than 0.01) and 166 +/- 21 to 220 +/- 24 mumol/l red blood cell/hr (p less than 0.05), respectively. Mean intracellular Na+ content in erythrocytes decreased from 11.4 +/- 0.40 to 10.0 +/- 0.33 mmol/l (p less than 0.01) and exchangeable Na+ from 39.8 +/- 0.6 mmol/kg to 35.6 +/- 0.6 mmol/kg (p less than 0.001). Sodium reduction correlated with the recovery of Na(+)-K(+)-Cl- cotransport activity (r = -0.65, p less than 0.01). During treatment, systolic and diastolic blood pressures were reduced significantly (p less than 0.01). In 12 patients treated with hydrochlorothiazide, Na(+)-K(+)-Cl- cotransport, Na(+)-K+ pump, Na(+)-Li+ countertransport, and Na+ permeability did not change significantly while Na+ content decreased from 11.7 +/- 0.3 to 10.3 +/- 0.2 mmol/l (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of cilazapril in hypertensive patients with renal impairment.

The aim of the study was to evaluate the clinical and renal hemodynamic effects of cilazapril in 10 hypertensive patients with moderate-to-severe chronic renal failure (creatinine clearance 14-50 ml/min). After 2 weeks of placebo, cilazapril 0.5 mg/day was given, and the dose was increased up to 5 mg/day if sitting diastolic blood pressure (SDBP) was not normalized (less than or equal to 90 mm Hg). Once a normal SDBP value was achieved, the patients remained on the given dose regimen for 6 months. After this period SDBP decreased from 107 +/- 2 to 95 +/- 2 mm Hg (p less than 0.001). At the end of treatment, glomerular filtration rate (GFR) remained unchanged in five patients, improved in four patients, and slightly decreased in one patient, the slope from baseline being 0.137 and the variation of GFR per unit of GFR at baseline being between -0.20 and 0.47. Likewise, effective renal plasma flow increased not significantly, showing considerable variability. Urinary protein excretion was reduced significantly from 2.51 +/- 0.75 to 0.51 +/- 0.10 g/L (p less than 0.05), suggesting that converting enzyme inhibition may exert a renal protective effect. In conclusion, it appears that cilazapril does not induce functional damage in the kidney of predialysis hypertensives.

Effects of ACE inhibition on renal haemodynamics in essential hypertension and hypertension associated with chronic renal failure.

Angiotensin II has many actions in the kidney, including regulation and distribution of renal circulation and glomerular filtration, as well as effects on mesangial contraction and on the filtration coefficient. The reduction in circulating and intrarenal angiotensin II by angiotensin converting enzyme (ACE) inhibitors in essential hypertension is associated with a significant increase in renal blood flow and a decrease in filtration fraction, without changes in glomerular filtration rate. In addition, administration of ACE inhibitors can reduce proximal sodium reabsorption via changes in peritubular hydrostatic and oncotic forces resulting from the fall in postglomerular capillary resistance. In severe hypertension the state of the renal vasculature does not allow ACE inhibition to induce similar haemodynamic changes and, therefore, it cannot contribute to renal sodium handling that requires the recruitment of alternate mechanisms. In spite of this, ACE inhibitors may exert a protective effect on the renal function of patients with severe hypertension as well as in those with renal impairment, by lowering systemic and, probably, intraglomerular pressure, reducing proteinuria and slowing the progression of renal failure.