Original Papers: PDF OnlyAltered cations and muscle membrane ATPase activity in deoxycorticosterone acetate-salt spontaneously hypertensive ratsTouyz, Rhian M.1; Marshal, Peter R.*; Milne, Frank J.1Author Information 1From the Department of Medicine, University of the Witwatersrand Medical School, Johannesburg *The Medical Research Council Research Unit for the Design of Catecholaminergic Drugs, Department of Pharmacology, Potchefstroom University, Potchefstroom, South Africa Journal of Hypertension: August 1991 - Volume 9 - Issue 8 - p 737-750 Buy Abstract The role of ions and cell membrane function in the pathogenesis of benign and malignant hypertension was investigated in spontaneously hypertensive rats (SHR). Ten-week-old male SHR (n=50) and SHR treated with deoxycorticosterone acetate (DOCA; n=70) and 1% NaCI drinking water were studied weekly for 14 weeks. Malignant hypertension developed only in DOCA-salt SHR and was characterised by severe hypertension, failure to thrive and renal fibrinoid necrosis. Fourteen DOCA-salt SHR and one SHR died. Extracellular (serum) and intracellular (erythrocyte and muscle) Na +, K +, Mg2+, Ca2+ and muscle membrane Na+,K + -adenosine triphosphatase (ATPase), Ca2+-ATPase and Mg2+-ATPase were measured at various stages in the development of malignant hypertension. Three developmental phases were defined: benign, premalignant and malignant. DOCA-salt SHR showed persistent hypokalaemia. In the benign phase, there were no differences in Na+, Mg2+ and Ca2+ between SHR and DOCA-salt SHR. In the premalignant phase, serum and erythrocyte Mg2+ and ATPase activity were significantly lower in DOCA-salt SHR compared with SHR. During the late premalignant and malignant phases, intracellular Ca2+ and Na+ were significantly higher in the DOCA-salt SHR compared with SHR. In view of these findings, the abnormalities in DOCA-salt SHR during the early phases of blood pressure elevation could be contributory factors to the development of malignant hypertension. © Lippincott-Raven Publishers.