Sex chromosome complement contributes to sex differences in bradycardic baroreflex response

CAEIRO XE; MIR FR; VIVAS LM; CARRER HF; CAMBIASSO MJ

HYPERTENSION

LIPPINCOTT WILLIAMS & WILKINS

Año: 2011 vol. 58 p. 505 - 511

0194-911X

To investigate whether sex chromosome complement modulates bradycardic baroreflex response and contributes to the angiotensin II–bradycardic baroreflex sex differences, we used the four core genotype mouse model in which the effect of gonadal sex and sex chromosome complement is dissociated, allowing comparisons of sexually dimorphic traits among XX and XY females, as well as in XX and XY males. In conscious gonadectomized (GDX) MF1 transgenic mice we evaluated baroreflex regulation of heart rate in response to changes in blood pressure evoked by phenylephrine (1 mg/mL), angiotensin II (100 μg/mL), and sodium nitroprusside (1 mg/mL). The administration of phenylephrine in GDX-XY females resulted in a significantly lower baroreflex response when compared with the other genotypes (in beats · min−1 · mm Hg−1 [slopes of regression lines for GDX-XY females −3.56±0.37 versus −6.06±0.38, −6.37±0.54 and −6.70±0.34 for GDX-XY male, GDX-XX female, and GDX-XX male mice, respectively]) {F(1,19)=9.63; P