Intracranial and Cerebral Perfusion Pressure Changes Induced by Increases in Intracerebroventricular Volume in Male and Female Dahl Salt-Sensitive Rats

The primary mechanism of intracranial pressure (ICP) adaptation to acute increases in arterial pressure (AP) is through autoregulation to maintain cerebral perfusion pressure (CPP). However, this mechanism is impaired in hypertension. We previously demonstrated that male rats with renovascular hypertension, which presents high renin-angiotensin system (RAS) activity, showed increased baseline levels of ICP and CPP compared to normotensive rats. Therefore, in the present study we aimed to evaluate the baseline levels of ICP and CPP in Dahl Salt-Sensitive (DSS) rats, a hypertensive model independent of high RAS activity and to assess the effects of increasing intracranial volume with intracerebroventricular (ICV) infusion of saline (0.15 M NaCl) on ICP and CPP. Male and female DSS rats (3-4 months of age) were used and randomly assigned to be fed with a normal salt diet (DSS-NS; 0.6% NaCl) or high salt diet (DSS-HS; 4% NaCl) for three weeks. After this period, rats were anaesthetized with (urethane,1.4 g/Kg, i.p.), tracheostomized, and one catheter was inserted in the femoral artery for mean AP (MAP) recording and other catheter was inserted in the right lateral ventricle (LV) for ICP recording. A needle was placed in the left LV to infuse 100 µl of saline for 10 min (10 µL/min rate). CPP was calculated by subtracting MAP and ICP. Male and female DSS-HS rats presented higher baseline MAP compared to their NS pairs (Male: 124 ± 9, vs NS: 90 ± 10 and Female: 134 ± 11, vs NS: 100 ± 8 mmHg, respectively; p < 0.05). While MAP was not changed during ICV infusion in males DSS-HS and NS, it was decreased in female DSS-HS compared to the baseline and DSS-NS (-13 ± 5 mmHg at 10 min of infusion, p < 0.05). Baseline ICP was comparable in male DSS-HS and NS (7.1 ± 2.3, vs NS: 8.1 ± 0.6 mmHg; p > 0.05), as well as the increase in ICP during the ICV infusion. Conversely, in the females, baseline ICP was greater in DSS-HS compared to NS (5.6 ± 2, vs NS: 1.7 ± 1.9 mmHg; p < 0.05), but ICP increased similarly in HS and NS during the ICV infusion. Baseline CPP was higher in male and female DSS-HS compared to their NS pairs (Male: 117 ± 5, vs NS: 82 ± 4 and Female: 128 ± 4, vs NS: 98 ± 5 mmHg, respectively; p < 0.05). During the ICV infusion, there was a decrease in CPP in male DSS-HS (-8.0 ± 4 at 10 min of infusion; p < 0.05) and in the female DSS-HS (-22 ± 5 mmHg at 10 min of infusion; p < 0.05) compared to their baseline and to the NS pairs. DSS-NS male and female did not present any change in CPP during ICV infusion. Although there are sex-specific differences in baseline ICP and in MAP responses to increased ICV infusion, an HS diet affects the ability to control CPP in both male and female DSS rats adequately. CNPq and CAPES Print (88887.194785/2018-00) 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.