Gender Differences in the Renal Function of Dahl Salt Sensitive Rats
Authors: Fonteles Manasses Claudino , Jorge Antônio Rafael Coelho , Martins Isabel Cristina Mendonça Torres , Oliveira Nádia Osório , Ferreira Paulo Maia , Nascimento Nilberto Robson Falcão , Santos Cláudia Ferreira , Costa Pedro Henrique Sá 
Published: November 2023

According to epidemiological studies, salt sensitive hypertension accounts for approximately 50% of cases of essential hypertension. Some studies have shown that salt sensitive women present aggravated hypertension in response to an overloaded salt diet, when compared to man at similar age. Thus, it is suggested that loss of sex hormones over menopause, mainly estradiol, contributes to impaired renal sodium handling, as observed in some studies with Dahl salt sensitive rats. In order to compare evaluate possible renal differences between mature DS male and female, in the absence of neural and humoral mechanisms, we have used isolated perfused rat kidney method. Isolated kidneys from aged (18‐month‐old) male (M) and female (F) DS rats weighing 320 to 380g (n=9) were perfused with Krebs‐Henseleit solution containing 6g% of bovine serum albumin previously dialyzed for 24 hours and perfused for 120 minutes. The gender differences were studied on glomerular filtration rate (GFR), urinary flow (UF), perfusion pressure (PP), renal vascular resistance (RVR) and percentage of total transport of sodium (%TNa+) and potassium (%TK+) at 30, 60, 90 and 120 minutes of experiment. All data were analyzed by unpaired t test with level of significance of *p<0,05. The experimental protocols were approved by the State University of Ceará Animal Research Ethic al Committee, license number of 11516758‐7/61. Females had increased PP at 90 and 120 minutes (PP90F=156.00 ± 7.00 vs. PP90M=147 7.40 ± 2.30; PP120F=156,80 ± 6.98 vs. PP120M=148.60 ± 4.09 mmHg.mL‐1.g‐1). RVR was raised in females at all evaluated times (RVR30F=7.58 ± 0,81 vs. RVR30M=3.60 ± 0.56; RVR60F=8.87 ± 1.23 vs. RVR60M=3.51 ± 0,57; RVR90F=8.79 ± 0.87 vs. RVR90M= 3.51 ± 0.51; RVR120F=10.20 ± 0.88 vs. RVR120M=3.19 ± 0.43 mmHg/mL.g‐1.min‐1). In addition, female had increased %TNa+ also at all evaluated times (%TNa+ 30F=76.67 ± 7.55 vs. %TNa+ 30M=69.75 ± 1.21; %TNa+ 60F=84.47 ± 5.81 vs. %TNa+ 60M=42.42 ± 3.34; %TNa+ 90F=77.20 ± 5.8 vs. %TNa+ 90M=44.86 ± 2.64; %TNa+ 120F= 65.67 ± 6.22 vs. %TNa+ 120M=41.14 ± 2.10). On the other hand, female rats had decreased UF at all the periods (UF30F=0.06 ± UF30M vs. 0.11 ± 0.03; UF60F=0.06 ± 0.01 vs. UF60M= 0.12 ± 0.01; UF90F=0.05 ± 0.01 vs. UF90M=0.10 ± 0.01; UF120F=0.01 ± 0.009 vs. UF120M= 0,11 ± 0.006 mL.g‐1.min‐1). GFR was diminished at 30 minutes in female rats (GFR30F=0.13 ± 0.02 vs. GFR30M=0.37 ± 0.10 mL.g‐1.min‐1). Finally, female had decreased %TK+ at all the times (%TK+ 30F=21.10 ± 13.55 vs. %TK+ 30M=74.75 ± 2.61; %TK+ 60F=2.93 ± 9.92 vs. TK+ 60M=55.61 ± 3.83; %TK+ 90F=26.00 ± 8.98 vs. %TK+ 90M=47.18 ± 2.87; %TK+ 120F=9.18 ± 11.75 vs. %TK+ 120M= 37.29 ± 4.52). In rats, menopause starts around 15 months of age. It has been shown that menopause occurs earlier in Dahl salt sensitive females when compared to other rat strains. Because of the age of our animals, it is possible that both changes in glomerular and tubular functions in females, are related to estradiol deficit. In addition, some studies have shown that renin‐angiotensin‐aldosterone system (RAAS) is upregulated in menopause. Thus, it is feasible that excess of RAAS components, mainly angiotensin II and aldosterone, may act by increase of RVR and changing %TNa+ and %TK+ in female DS rats.

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