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Arterial hypertension is nowadays no longer considered an isolated disorder of blood pressure regulation but a multifactorial disease with metabolic and cellular deviations. From the therapeutic aspect of thus conceived hypertension today inhibitors of the angiotensin converting enzyme seem most promising. With regard to their assumed comprehensive effect, the authors investigated simultaneously selected pressor and depressor humoral indicators and other indicators in 21 hypertensive patients with stage I and II of essential hypertension before and after three-month treatment with an angiotensin converting enzyme inhibitor lisinopril (Prinivil, Merck, Sharp and Dohme) and compared them with findings in 21 normotensive healthy subjects. Hypertensive subjects before treatment had, as compared with normotensives, significantly lower urinary kallikrein (7.8 +/- 1.218.0 +/- 4.2 EU/24hr, a significantly higher basal plasma adrenalin (1.27 +/- 0.200.54 +/- 0.20 pmol/ml) and adrenalin after a glucose load (1.26 +/- 0.220.51 +/- 0.12) and a higher relative plasma viscosity (1.74 +/- 0.021.67 +/- 0.01). The two groups did not differ significantly as to the plasma renin activity, plasma aldosterone and fibrinogen concentration and the level of urinary prostaglandins per 24 hr: 6-keto-prostaglandin F1a, thromboxane B2 and prostaglandins E and F2a. The 75 g glucose load produced an increased plasma renin, aldosterone and noradrenaline activity in normotensives as well as hypertensives before and after lisinopril treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma concentration of two main cardiovascular substances - atrial natriuretic factor (ANF) and endothelin - were studied in control subjects (n = 21) under basal conditions and 90 minutes after oral administration of glucose. In hypertensive patients (n = 21) these determinations were repeated after 12 weeks treatment with an angiotensin I-converting enzyme inhibitor lisinopril (Prinivil, Merck Sharp and Dohme). While basal and post-glucose ANF concentrations did not differ in controls and hypertensive patients, a tendency to the higher endothelin levels was found in our group of essential hypertension when compared to normotensive subjects. Glucose loading did not change significantly ANF concentrations in any studied group but significantly lowered plasma endothelin in both controls (from 13 +/- 0.95 to 9.50 +/- 0.95 fmol/ml) and hypertensive patients (from 15.05 +/- 1.23 to 12.15 +/- 1.03 fmol/min). Treatment of hypertensive patients with lisinopril paradoxically increased concentrations of ANF (from 6.43 +/- 2.53 to 11.47 +/- 4.90 fmol/ml) and lowered that of endothelin (from 15.05 +/- 1.23 to 12.17 +/- 1.58 fmol/ml). From our findings we may suggest that the relative predominance of the vasoconstrictor (endothelin) over the vasodilator (ANF) humoral substances might participate in pathogenesis of EH and that the reversal of this disadvantageous ratio after lisinopril (increase of ANF and decrease of endothelin) might contribute to the blood pressure reducing effect of ACEI. The drop in plasma endothelin after glucose remains so far unexplained consequence of glucose loading in both control and hypertensive subjects.

Hyperinsulinaemia and insulin resistance are associated with essential hypertension irrespective of obesity and non-insulin-dependent diabetes mellitus. One of the mechanisms whereby hyperinsulinaemia may play a role in the increase in blood pressure, is an increased activity of the sympathetic nervous system. The authors studied the incidence of hyperinsulinaemia, and the possibility of modulating it by 12-week administration of the ACE inhibitor (ACEI) lisinopril (Prinivil by MSD) at a dose of 20-40 mg/day. Compared with normotensive subjects, hypertensives showed a degree of hyperinsulinaemia and insulin resistance (higher blood glucose at higher immunoreactive insulin and C-peptide concentrations, and a higher IRI/blood glucose ratio) as well as manifestations of enhanced sympathetic activity (higher adrenaline levels). Lisinopril had a favourable effect not only on blood pressure but, also, on hyperinsulinaemia and adrenaline levels. It can be reasonably concluded that therapy with ACEI, in addition to its antihypertensive effect, may also favourably modulate some pathogenic and metabolic factors in essential hypertension.