RESUMO
Single sublingual administration of nifedipine at a dose of 20 mg to patients with essential hypertension (EH) with subsequent hemodynamic observation every hour for 4 h resulted in the reduction of systolic and diastolic arterial pressure (AP) by 10-15%, arteriolar tone (AT) by 30-40%. Renal metabolism was assessed by the presence of slow isoenzymes of carbonic esterases in urine. They were absent in healthy persons; before nifedipine administration they were detected in 62% of cases, after it--in 22%. Regular administration of nifedipine (30-60 mg/day) and verapamil (160-240 mg/day) in a less severe course of EH (AT less than 4500 conv. units) improved the renal blood flow decreasing AT and AP. Severe EH (AT greater than 4500 conv. units) was characterized by cases of inadequate action of the drugs: dramatic reduction of ERF was followed by a rise of AT and AP which could be accounted for by excessive vasodilation at the 1st stage with further development of the renal steal syndrome and a rise of AP and AT. In such cases lower doses of nifedipine, the combination of verapamil with hydrochlorthiazide and verapamil with prazosin hydrochloride were more effective; the combination of nifedipine with propranolol did not prevent a negative effect on the kidneys and was ineffective in high AT.
