engleski

Arteriolar reactivity to dilator agents and elevated PO2in Dahl S and renin congenic rats

The renin-angiotensin system (RAS) plays an important role in maintaining normal vascular reactivity. Dahl salt-sensitive (Dahl S) rats exhibit low renin levels and impaired responses to vasodilator stimuli. Renin-congenic (RGRR) rats, derived by transfer of a region of chromosome 13 containing the renin gene from the Dahl salt-resistant strain onto the genetic background of the Dahl S strain, exhibit normal modulation of plasma renin activity. In the present study, age-matched male RGRR and Dahl S rats were fed low salt (LS) (0.4% NaCl) or high salt (HS) diet (4% NaCl) for 4 weeks with water ad libitum. The responses of third order arterioles of the in situ cremaster muscle to acetylcholine (ACh), sodium nitroprusside (SNP) and elevation of superfusate O2 concentration from 0% O2 to 21% O2 were assessed by video microscopy. ACh induced dilation was impaired in arterioles of Dahl S rats on HS diet, compared to controls on LS diet and RGRR rats on HS diet. In RGRR, transfer of the renin gene restored dilator responses to ACh in rats on either diet. SNP dilation was similar in Dahl S rats and RGRR rats, regardless of diet. HS diet augmented O2 induced constriction of arterioles of both Dahl S rats and RGRR rats. These data suggest that restoration of normal renin control mechanisms contribute to the recovery of vasodilator responses in RGRR rats, but do not impact constrictor responses to elevated PO2. (NIH #HL29587 and #HL-65289)

hypertension; arterioal reactivity; dilatator agents

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