4-nitrophenyl phosphatase activity of the red blood cell membrane in essential hypertension.

In this paper we report the levels of the 4-nitrophenyl phosphate hydrolysing activity of the red blood cell membrane in 46 hypertensive patients as compared to 41 normal controls and eight secondary hypertensives. This activity has at least two components; one of them is dependent on the presence of magnesium and potassium ions, and more sensitive to sodium, ATP, heat and -SH blockers than the cation-independent activity. This component appears increased in membranes from essential hypertension patients, correlating to the clinical seriousness of the condition, while remaining at control level in the secondary hypertension patients. The cation-independent component of this activity does not differ significantly in any of the groups studied.