Afferent Renal Denervation and ENaC Blockade Each Prevent Chlorthalidone-Induced Salt Appetite in Sprague Dawley Rats

The average American consumes approximately 3.4g sodium per day, ~1g more than the American Heart Association’s recommended daily maximum. Reducing sodium intake is one of the most cost-effective ways to reduce death from non-communicable diseases and improve health outcomes. We have recently demonstrated that the kidneys play a role in the regulation of salt appetite in male DOCA-salt rats, a model of primary aldosteronism. Afferent renal denervation (ARDN) caused a significant and sustained reduction in sodium intake in the absence of an effect on water intake. In the current study we tested the hypothesis that increased sodium delivery to the collecting duct results in increased ENaC mediated sodium reabsorption and subsequently increased afferent renal nerve activity and salt appetite. To test this we treated Sprague Dawley rats daily with chlorthalidone (CTD) to inhibit the sodium-chloride cotransporter (NCC) in the distal convoluted tubule. CTD increases sodium delivery to the collecting duct and is associated with increased ENaC activity. We examined whether CTD causes an increase in salt intake and if this could be prevented by amiloride and ARDN. Four groups of each male and female Sprague-Dawley rats (aged 10-14 weeks) were studied: Vehicle (peanut butter, p.o, n=9M, 5F), CTD (5mg/kg, p.o, n=8M, 5F), CTD-ARDN (n=6M, 7F), and CTD-Amiloride (5mg/kg CTD + 10mg/kg amiloride, p.o, n=4M). The CTD-ARDN group underwent bilateral ARDN (periaxonal capsaicin, 33mM). The remaining three groups underwent sham surgery. Telemeter catheters were inserted in the femoral artery of all rats to assess mean arterial pressure (MAP). Following recovery, all rats had ad libitum access to a low-salt diet (0.01% NaCl), deionized water, and 1.8% saline for 14 days. CTD resulted in a substantial increase in saline intake compared to the vehicle rats (males p<0.001, females p=0.061) without affecting water intake (males p=0.413, females p=0.931). ARDN significantly reduced saline intake (males p=0.02, females p=0.005) but did not affect water intake (males p=0.5, females p=0.931). In male rats, amiloride reduced CTD-induced saline intake to a comparable extent as ARDN (p=0.924 CTD-ARDN vs. CTD-amiloride) but had no effect on water intake. MAP was equivalent between all groups. Ongoing studies are evaluating the effect of amiloride on CTD-induced salt appetite in female Sprague Dawley rats. These studies demonstrate, for the first time, that inhibition of NCC causes a specific increase in salt appetite, which is driven by the activation of the afferent renal nerves. Notably, amiloride prevented CTD-induced salt appetite to a comparable extent as ARDN suggesting a common mechanism of action. LCE is funded by R01HL152166 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.