title: Hemodynamic responses to acute angiotensin II infusion are exacerbated in male versus female spontaneously hypertensive rats.
abstract: We previously reported that male spontaneously hypertensive rats (SHRs) are more sensitive to chronic angiotensin (Ang) II-induced hypertension compared with female rats. This study was designed to test the hypothesis that anesthetized male SHRs are also more responsive to acute Ang II-induced increases in blood pressure and renal hemodynamic changes when compared with female SHRs. Baseline mean arterial pressure (MAP) was higher in male SHRs than in female SHRs (135 ± 2 vs. 124 ± 4 mmHg, P < 0.05). Acute intravenous infusion of Ang II (5 ng/kg/min) for 60 minutes significantly increased MAP to 148 ± 2 mmHg in male SHRs (P < 0.05) without a significant change in MAP in female SHRs. Baseline glomerular filtration rate (GFR) was also higher in male SHRs than in female SHRs (2.6 ± 0.3 vs. 1.3 ± 0.1 mL/min, P < 0.05). Ang II infusion for 60 min significantly decreased GFR in male SHRs (2.0 ± 0.2 mL/min; P < 0.05) without significant changes in urine flow rate, sodium, or chloride excretion. In contrast, Ang II infusion increased GFR in female SHRs (1.9 ± 0.2 mL/min; P < 0.05). The increase in GFR upon Ang II infusion in female SHRs was associated with increases in urine flow rate (4.3 ± 0.3 to 7.1 ± 0.9 μL/min), sodium excretion (0.16 ± 0.04 to 0.4 ± 0.1 μmol/min), and chloride excretion (0.7 ± 0.08 to 1.1 ± 0.1 μmol/min; for all P < 0.05). These findings support the hypothesis that there is sex difference in response to acute Ang II infusion in SHRs with females being less responsive to Ang II-induced elevations in blood pressure and decreases in GFR relative to male SHRs.
authors.affiliation: Departments of Oral Biology, Augusta University, Augusta, Georgia Departments of Pharmacology & Toxicology, Augusta University, Augusta, Georgia aelmarakby@gru.edu.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Elmarakby
authors.affiliation: Departments of Physiology, Augusta University, Augusta, Georgia.
authors.forename: Kanchan
authors.initials: K
authors.lastname: Bhatia
authors.affiliation: Departments of Physiology, Augusta University, Augusta, Georgia.
authors.forename: Ryan
authors.initials: R
authors.lastname: Crislip
authors.affiliation: Departments of Physiology, Augusta University, Augusta, Georgia.
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Sullivan
mesh_terms: D000804:Angiotensin II / Q000008:administration & dosage* / Q000633:toxicity; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects / Q000502:physiology*; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology*; D007262:Infusions, Intravenous; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D012727:Sex Characteristics
chemical_list: D000804:Angiotensin II
keywords: Ang II; GFR; SHR; blood pressure; sex