Sry increases sodium reabsorption in the Wistar Kyoto rat kidney

Abstract

Our lab has identified a locus on the Y chromosome of the Spontaneously Hypertensive Rat that is associated with a 20–25 mmHg increase in Blood Pressure (BP). A candidate for this locus is the Sry gene, also known as the testis determining factor. We have shown that Sry inserted into a mammalian expression vector and electroporated into the kidney of the normotensive Wistar-Kyoto rat, produced a 50% increase in plasma norepinephrine content after 2 weeks compared to vector controls. The aim of the current research was to investigate if exogenous Sry increased the activity of the renal Na+/K+ ATPase pump and decreased urinary Na+ excretion in the WKY strain. Age-matched WKY adult male rats were electroporated either with the Sry expression construct or an empty vector and kidney function evaluated by 24 hr creatinine clearance, urine Na+ excretion rate, urine electrolyte concentration by flame photometry and BP by tail-cuff sphygmomanometry. At 11 days post-electroporation no difference was found in GFR. However, the Sry group had an average increase in BP of 17 mmHg compared to empty vector controls (p<0.05) and excreted 33% less Na+ compared to controls (p<0.05). Despite an increase in BP which increases pressure natriuresis, the Sry group retained more Na+ than the empty vector controls. Our results are consistent with the idea that one function of Sry may be renal regulation of Na.