Atrial Natriuretic Peptide-Induced Inhibition of Amiloride-Sensitive ²²Na⁺ Uptake into Cerebral Capillaries of Spontaneously Hypertensive Rats

Abstract

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 μM α-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.