Erythrocytic protein kinase C activity in primary hypertension

Ek P, Toomik R, Eriksson S, Frithz G, Ronquist G, Engström L (University of Uppsala and University Hospital, Uppsala; and Central Hospital, Eskilstuna, Sweden). Erythrocytic protein kinase C activity in primary hypertension. J Intern Med 1998; 243 : 299–305.

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× 10⁶ cells, regardless of sex and age. The corresponding value for patients with primary hypertension was 0.16 ± 0.04 pmol [³²P]phosphate min^?1× 10⁶ 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.