Insertion of the Renin Gene from the Brown Norway Rat Restores Normal Vasodilation Mechanisms when Placed onto the Dahl Salt‐Sensitive Genetic Background

The Dahl Salt Sensitive (SS) rat exhibits impaired regulation of the renin‐angiotensin system (RAS), chronically low levels of angiotensin II, and altered vascular reactivity in the form of impaired responses to vasodilator stimuli. Insertion of the 13 th chromosome from the normotensive Brown Norway (BN) rat by selective breeding with SS rats restores proper function of the RAS and returns responses to vasodilator stimuli to normal in SS.13 BN consomic rats. The present study investigates responses to vasodilator stimuli in two different congenic strains in which a portion of the BN chromosome 13 was inserted onto the SS genetic background. The Line 6 strain contains a 3.3 mb portion of the chromosome which excludes the renin gene, while the Line 9 strain contains a 2.5 mb portion flanking the Line 6 region which includes the renin gene. Male Line 9 and Line 6 congenic rats were fed a low salt diet (.4% NaCl) after weaning. At the age of 10–11 weeks, middle cerebral arteries (MCA) were isolated and cannulated and dilator responses to acetylcholine (10 μM) and reduced PO 2 were assessed using television microscopy. MCA from the Line 9 congenic strain dilated in response to acetylcholine and reduced PO 2 while the MCA from the Line 6 congenic strain did not. These results indicate that the presence of a normally functioning renin gene from the BN rat in the SS genetic background restores normal vasodilator response in the MCA. [NIH #HL‐29587; #HL‐65289, and #HL‐72920].