Subcellular Membrane Properties in Vascular and Non-Vascular Smooth Muscles of Dahl Hypertensive Rats

Subcellular membrane fractions were isolated from mesenteric arteries and vas deferens of salt-resistant and salt-sensitive Dahl rats on low-salt (0.4% NaCl) high-salt (8.0% NaCl) diets. Only the salt-sensitive Dahl rats on the high-salt diet developed sustained high blood pressure (BP) after 5 weeks of the high-salt diet. Protein contents, membrane associated enzyme activities, calcium ion (Ca2+) binding and ATP-dependent CA2+ transport were compared in fractions isolated from all four groups. No obvious changes were observed, except for minor enhancement in magnesium ion (Mg2+)- and CA2+ ATPase activities of mesenteric arterial membranes isolated from salt-sensitive Dahl rats on high-salt diet compared to those from other groups of rats. The membrane fractions from vas deferens of salt-sensitive Dahl rats on the high-salt diet, on the other hand, showed decreased ATP-dependent Ca2+ transport compared to those from salt-sensitive Dahl rats on the low-salt diet. No difference was observed in membrane fractions isolated from salt-resistant Dahl rats on high-salt diet compared to those on low-salt diet. The significance of these observations are discussed in relation to the findings previously obtained from corresponding smooth muscle tissues of spontaneous hypertensive rats (SHR).