THE ROLE OF ENDOGENOUS-DIGITALIS-LIKE-FACTOR IN BLOOD-PRESSURE REGULATION IN ESSENTIAL-HYPERTENSION

We examined plasma renin activity (PRA), plasma aldosterone (PA), atri al natriuretic factor (ANF) and endogenous digitalis-like factor (DLF) in 15 healthy subjects and 15 patients with essential hypertension (E H) to obtain basal values and values after extracellular fluid volume (ECFV) expansion caused by infusion of isotonic saline solution over a period of 2 hours (20 mg/kg). A significant increase in diuresis and natriuresis accompanied by a decrease in PRA and PA and an increase in ANF was observed in both groups. No significant differences were obse rved in ANF levels between normotensive subjects and hypertensive pati ents. Hypertensive patients showed significantly higher basal values o f DLF than normotensive subjects. However, an increase in plasma DLF f ollowing ECFV expansion was observed only in the group of healthy subj ects. There was a positive correlation between ANF and natriuresis and a negative correlation between ANF and systolic and diastolic blood p ressure (BP). Changes in DLF correlated positively with changes in dia stolic BP in both groups, while in healthy subjects a negative correla tion was recorded between PRA and DLF. We conclude that the increased diuresis and natriuresis in ECFV expansion is presumably accounted for not only by suppression of PRA and PA, but also by stimulated ANF sec retion, while in healthy subjects stimulation of DLF may be involved a s well. The insufficient DLF response to saline infusion may indicate an exhausted DLF reserve in hypertensive patients. As a vasoactive sub stance, DLF can participate in the regulation of blood pressure and pl ay a role in the pathogenesis of arterial hypertension.