Objectives: Increased protein kinase C activity has been reported in erythrocytes from patients with primary hypertension and also from hypertensive rats. In this phenomenological study, we investigated whether a possible increased activity was the result of an augmented amount of enzyme molecules or a more active enzyme.
Design: Collect blood samples, separate erythrocytes from other blood cells. After partial purification of protein kinase C in the erythrocyte lysate, assay the enzyme activity under optimal conditions using a specific peptide substrate.
Setting: Central Hospital in Eskilstuna and University Hospital in Uppsala, Sweden.
Subjects: Healthy individuals: 47 persons (20 women and 27 men). Ten patients with untreated primary hypertension.
Main outcome measures: Erythrocytes were separated from leucocytes and platelets by passing through a cellulose column followed by repeated washings. Some proteins in the erythrocyte lysate interfering with protein kinase C assay were removed by chromatography on DEAE-cellulose.
Results: The mean protein kinase C activity in erythrocytes from healthy individuals was 0.18 +/- 0.02 pmol [32P]phosphate min(-1) x 10(6) cells, regardless of sex and age. The corresponding value for patients with primary hypertension was 0.16 +/- 0.04 pmol [32P]phosphate min(-1) x 10(6) cells.
Conclusions: The amount of protein kinase C, measured as the activity at optimal assay conditions, in erythrocytes from patients with primary hypertension is not critical for the development of moderate hypertension.