Atrial natriuretic peptide-induced inhibition of amiloride-sensitive 22Na+ uptake into cerebral capillaries of spontaneously hypertensive rats.

22Na+ uptake into capillaries isolated from the cerebral cortex of adult (20- to 26-week-old) sustained-hypertensive spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHRSP) was compared with findings in age-matched Wistar Kyoto rats (WKY). In the presence of 1.0 mM ouabain, 1.0 mM furosemide and 2.0 mM LiCl, 22Na+ uptake into the isolated cerebral capillaries of WKY and SHR was significantly reduced to 38% and 65% of the control values, respectively, when 0.1 microM alpha-rat atrial natriuretic peptide (rANP) was added to the uptake buffer. The rANP-induced inhibition observed in SHR was significantly less, as compared with that in the WKY. Noteworthy was the observation that the Na+ uptake into the cerebral capillaries of SHRSP was not inhibited by rANP. As this peptide is thought to regulate amiloride-sensitive Na+ transport from the blood to brain by interacting with specific receptors, the present finding may relate to the etiology of dysfunction of the blood-brain barrier, in the presence of hypertension.