High-fat loading abolishes sex differences in blood pressure (BP) responses to high-salt in Dahl rats

Abstract

There are numerous reports that male Dahl rats have greater increases in BP with a high-salt (HS) diet than females, yet women have been suggested to be more salt-sensitive than men. Since the typical Western diet consists of both HS and high-fat (HF), the goal of the present study was to test the hypothesis that HF loading and a combined HF/HS would abolish the protection observed in female Dahl rats vs. males. To test our hypothesis, 6 week old male and female Dahl rats were implanted with telemetry devices to continuously measure mean arterial BP; n=6. Rats were allowed to recover for one week followed by one week of baseline BP recording. Rats were then placed on a HF diet (60% kcal from lard; Bio-Serv) for 2 weeks followed by a HF/HS (4% salt; Bio-Serv) for an additional 2 weeks. Rats were placed in metabolic cages prior to starting HS and after 2 weeks to collect a 24 hour urine sample to measure urinary protein and albumin excretion. Glomerular filtration rate (GFR) was measured at the end of the study conscious freely moving animals using FITC-inulin elimination method. Baseline BP values were comparable between males (115±5 mmHg) and females (117±3 mmHg; p=0.67). BP increased during HF diet treatment, yet BP values remained similar in males and females (133±7 vs. 134±3 mmHg, respectively; p=0.93). Interestingly, females had a greater increase in BP on HF/HS vs. males that reached significance by the end of the study (146±7 vs. 160±6 mmHg, respectively; p=0.03). Despite this, urinary protein (185±23 vs. 94±19 mg/day; p=0.001) and albumin (142±22 vs. 56±13 mg/day; p=0.006) excretion were greater in males than in females. However, GFR was comparable between males and females (0.55 ± 0.03 vs. 0.45 ± 0.04 ml/min/100 g of body weight; p=0.07). In conclusion, female Dahl rats are not protected from HS diet when also challenged with HF, supporting our hypothesis that HF loading eliminates cardiovascular protection in females vs. males. However, males exhibited greater renal injury. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.