CHRONIC CENTRAL POTASSIUM INFUSION PREVENTS DEOXYCORTICOSTERONE-SALT HYPERTENSION IN RATS

Although it has long been established that cerebrospinal fluid potassium concentration (CSF [K]) is very tightly regulated, it has been reported that rats made hypertensive by central infusions of aldosterone have significantly lower CSF [K] compared with normotensive controls. We investigated whether reduced CSF [K] is also present in another animal model of hypertension, the deoxycorticosterone acetate (DOCA)-salt rat, and we hypothesized that chronic intracerebroventricular (IVT) infusion of potassium with miniosmotic pumps might attenuate the rise in blood pressure observed in these rats. DOCA-salt rats without TVT infusions or with control CSF infusions (0.5 mu l/h of 2.9 mM K for 2 wk) had a significantly increased systolic blood pressure and a significantly lower CSF [K] compared with their respective sham groups. In contrast, DOCA-salt rats receiving TVT infusions with elevated [K] (10, 30, or 150 mM) had significantly lower blood pressures compared with those receiving control CSF. They also did not exhibit decreased CSF [K] compared with their respective sham groups. At 10 and 150 mM K, the blood pressure rise in DOCA-salt rats was not significantly different from shams. At 30 mM K, there was a slight, but significant, increase in blood pressure in the DOCA-salt rats compared with their shams, but this rise was still much less than in DOCA-salt rats infused with 2.9 mM K. Infusions with elevated [K] had no effect on blood pressure in the sham animals. These studies suggest that altered brain potassium homeostasis may play an important role in the development of DOCA-salt hypertension.