Decreased hindquarters venous distensibility during high salt intake in stroke-prone spontaneously hypertensive rats

This study was done to examine whether high salt intake decreases venous distensibility in stroke-prone spontaneously hypertensive rats (SHR-sp). Ten weeks old male SHR-sp and normotensive Wistar-Kyoto rats (WKY) were fed either high (8%) or pressure-volume curves were obtained by infusing Krebs-Henseleit solution retrograde into the inferior vena cava at a rate of 12 or 2.1 ml/min. After 3 weeks of dietary treatment, high salt intake shifted the venous pressure-volume curves at maximal venodilatation caused by nitroprusside toward the pressure axis in SHR-sp but not in WKY. The venous pressure-volume curve during interruption of infusion was also shifted toward the pressure axis in SHR-sp on high salt diet as compared with that in SHR-sp on normal salt diet. Water content and thickness of the smooth muscle layer of the venous wall were not different between the two groups of SHR-sp. These results suggest that high salt intake for 3 weeks decreased hindquarters venous distensibility at maximal venodilatation in SHR-sp but not in WKY. The salt-induced decrease in venous distensibility in SHR-sp might be related to changes in interstitial space compliance or the adventitia since water content or thickness of the smooth muscle layer of the venous wall was not altered.