Pregnant rats were fed either normal salt (NS) (1% NaCl) or HS (8% NaCl) diet for the whole gestation. Offspring were maintained on NS diets. Renal interlobar arteries in offspring were tested for vascular responses to phenylephrine (Phe), K+ channels and signal pathways related to sGC.
Phe induced higher vessel tension in interlobar arteries of the HS offspring. Following pretreatment with BKCa channel inhibitor iberiotoxin, Phe-mediated vasoconstrictions were decreased in HS offspring compared to NS. Phe-mediated constrictions following pretreatment with NO synthase inhibitor N(G)-nitro-l-arginine methyl ester or sGC inhibitor 1H-1,2,4-oxadiazolo-4,3-quinoxalin-1-one in the HS offspring were less sensitive than NS. The whole-cell K+ currents and the component of BKCa channels were not changed in smooth muscle cells from interlobar arteries, whereas the K+ currents stimulated by sGC activator BAY41-2272 were reduced in the HS offspring. The protein expressions of sGC β1 and β2 in the interlobar arteries of HS offspring were reduced.
The results showed that chronic overintake of salt during pregnancy could increase renal vascular tone in the offspring. The affected signal pathways included down-regulation of sGC function and expression.