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Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice
Published on: February 14, 2021
Sex chromosome complement contributes to sex differences in bradycardic baroreflex response
Ximena E Caeiro1, Franco R Mir, Laura M Vivas
1Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Friuli 2434 (5016) Córdoba, Argentina.
Hypertension (Dallas, Tex. : 1979)
|August 4, 2011
Summary
Sex chromosome complement influences heart rate regulation. XY females show reduced baroreflex response to phenylephrine and angiotensin II compared to XX mice, indicating sex chromosome effects on cardiovascular control.
Area of Science:
- Cardiovascular Physiology
- Genetics
- Endocrinology
Background:
- Sex differences in cardiovascular regulation are well-documented.
- The role of sex chromosomes versus gonadal hormones in these differences remains incompletely understood.
- Baroreflex sensitivity, crucial for blood pressure homeostasis, exhibits sexual dimorphism.
Purpose of the Study:
- To investigate the independent effects of sex chromosome complement (XX vs. XY) on bradycardic baroreflex responses.
- To determine if sex chromosome complement contributes to sex differences in the angiotensin II-bradycardic baroreflex.
- To utilize the four core genotype mouse model to dissociate gonadal sex from chromosomal sex.
Main Methods:
- Used the four core genotype mouse model with XX and XY females and males.
- Evaluated baroreflex heart rate regulation in conscious, gonadectomized mice.
- Administered phenylephrine, angiotensin II, and sodium nitroprusside to evoke blood pressure changes and assess baroreflex responses.
Main Results:
- GDX-XY females exhibited significantly lower baroreflex response to phenylephrine compared to other genotypes.
- Angiotensin II-induced bradycardic baroreflex response was attenuated in both GDX-XY males and females versus GDX-XX mice.
- Reflex tachycardic responses to sodium nitroprusside were similar across all genotypes.
Conclusions:
- Sex chromosome complement modulates baroreflex heart rate inhibition in response to phenylephrine and angiotensin II.
- These findings support the hypothesis that sex chromosomes, independent of gonadal hormones, influence cardiovascular reflex regulation.
- Understanding these foundational sex differences may lead to sex-tailored therapeutic strategies for cardiovascular conditions.
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