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Diferencias raciales en las respuestas hemodinámicas al estrés térmico ambiental entre adolescentes
R M Kelsey1, B S Alpert, S M Patterson
1University of Tennessee College of Medicine, Memphis, USA. rkelsey@utmem.edu
Circulation
|May 16, 2000
Resumen
Los adolescentes negros muestran una mayor reactividad cardíaca y vasoconstrictiva al estrés por el frío en comparación con los adolescentes blancos. Estas diferencias en la reactividad vascular pueden contribuir al riesgo de hipertensión en los individuos negros.
Área de la Ciencia:
- Fisiología cardiovascular fisiología cardiovascular.
- Disparidades Raciales en la Salud.
- Salud de los Adolescentes.
Sus antecedentes:
- Investigaciones anteriores indican mayores respuestas de la presión arterial (BP) a los factores estresantes en los niños negros en comparación con los niños blancos.
- Los mecanismos cardíacos y vasculares específicos que subyacen a estas diferencias de reactividad de la presión arterial siguen sin estar claros.
- Se desconoce si las diferencias raciales en la reactividad vascular provienen de una vasoconstricción excesiva o una vasodilatación deficiente.
Objetivo del estudio:
- Investigar las contribuciones cardíacas y vasculares a las diferencias raciales en la reactividad de la presión arterial.
- Para determinar si las diferencias raciales en la reactividad vascular implican una vasoconstricción excesiva o una vasodilatación deficiente.
Principales métodos:
- BP evaluada, frecuencia cardíaca y cardiografía de impedancia (período de preejección [PEP] y resistencia periférica total [TPR]) en adolescentes negros (n=76) y blancos (n=60) sanos (edad media, 14,8 años).
- Respuestas evaluadas durante la exposición pasiva a una cámara fría (8-10°C) y a una cálida (40-42°C).
- Utilizó análisis de covarianza para explorar los mecanismos subyacentes.
Principales resultados:
- Los adolescentes negros mostraron mayores disminuciones en la PEP y aumentos en la TPR durante la exposición al frío en comparación con los adolescentes blancos (P<0,05).
- No se observaron diferencias significativas en las respuestas de los grupos durante la exposición al calor.
- Los análisis de covarianza sugirieron una mayor reactividad vasoconstrictiva cardíaca beta-adrenérgica y alfa-adrenérgica en adolescentes negros durante el estrés por frío.
Conclusiones:
- Los adolescentes blancos y negros mostraron respuestas miocárdicas y vasodilatadoras similares al estrés por calor.
- Los adolescentes negros demostraron una mayor reactividad miocárdica y vasoconstrictiva al estrés por el frío.
- Las diferencias raciales en la reactividad vascular parecen involucrar vasoconstricción en lugar de vasodilatación, lo que potencialmente contribuye al riesgo de hipertensión en individuos negros.
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