Artículos de revistas
Gender differentiation of the chemoreflex during growth at high altitude : functional and nerurochemical studies
Fecha
2000Institución
Resumen
The effect of chronic hypoxia on
gender differences in physiology and neurochemistry of chemosensory pathways was studied in prepubertal and adult rats
living at sea level (SL; Lyon, France) or at high altitude (HA;
La Paz, Bolivia, 3,600 m). HA adult rats had higher hematocrit (Ht%), Hb concentration, resting ventilatory rate (Ve100),
and higher tyrosine hydroxylase (TH) activity in carotid
bodies (CB) than SL animals. At HA and SL, adult females
had lower Ht% (46.0 +- 0.8 vs. 50.4 +- 0.6% at HA, P < 0.05
and 43.8 +- 0.9 vs. 47.1 +- 0.8% at SL, P < 0.05) and Hb (16.1 +-
0.3 vs. 17.7 +- 0.2 g/dl at HA, P < 0.05 and 14.5 +- 0.3 vs.
15.6 +- 0.1 g/dl at SL, P < 0.05) than males. Females had
higher Ve100 [170 +- 19 vs. 109 +- 7 ml·min-1·100 g-1 at HA,
P < 0.05 and 50 +- 3 vs. 40 +- 2 ml·min-1·100 g-1 at SL, not
significant (NS)] and lower CB-TH activity (1.40 6 0.2 vs.
3.87 +- 0.6 pmol/20 min at HA, P < 0.05 and 0.52 +- 0.1 vs.
0.68 +-6 0.1 pmol/20 min at SL; NS) than males at HA only. The
onset of hypoxic ventilatory response during development
was delayed at HA. Prepubertal HA females had higher Ve100
than males (2 wk old, 147%) and higher CB-TH activity (3 wk
old, +51%). Medullary noradrenergic groups were sex dimorphic during development at SL. Rats raised at HA had a drop
of TH activity between the second and the third postnatal
week in all medullary groups. In conclusion, our data support
the hypothesis that the CB is the major site for sexual
differentiation of the ventilatory control. Ventilatory differences appeared before puberty, and the animals bred at HA
had profound alterations in the developmental process of the
chemoreflex and its neural pathways. Some of these alterations are under dependence of the sex of the animal, and
there is an important interaction between gender and the
hypoxic environmental condition during the developmental
period.