Carotid sinus nerve section and the increase in plasma cortisol during acute hypoxia in fetal sheep.

AUTOR(ES)

Giussani, D A

RESUMO

1. We studied the effects of acute isocapnic hypoxia on plasma concentrations of adrenocorticotrophic hormone (ACTH) and cortisol in sixteen sheep fetuses at 118-125 days of gestation (term is 147 days). Eight fetuses had their carotid sinus nerves cut (denervation); the remaining eight had these nerves left intact. 2. There were no differences in the plasma concentrations of ACTH or cortisol between intact and denervated fetuses during normoxia. 3. Whilst plasma cortisol increased in early (after 15 min) and late (after 45 min) hypoxia in intact fetuses, the rise in cortisol in denervated fetuses was delayed, increasing significantly only by late hypoxia. 4. In contrast, plasma ACTH concentrations were increased in early and late hypoxia in both intact and denervated fetuses. The rise was smaller in denervated fetuses, but was not significantly different from that in intact fetuses. 5. Our results indicate that, in the sheep fetus, carotid sinus nerve section delays the rise in plasma cortisol in response to acute hypoxia without affecting the ACTH response. Further work is needed to establish the mechanism underlying this effect of denervation.

Documentos Relacionados

• Afferent and efferent components of the cardiovascular reflex responses to acute hypoxia in term fetal sheep.
• Effect of carotid denervation on plasma vasopressin levels during acute hypoxia in the late-gestation sheep fetus.
• Adenosine mediates metabolic and cardiovascular responses to hypoxia in fetal sheep.
• Pulmonary glucose transport in the fetal sheep.
• Restoration of lung liquid volume following its acute alteration in fetal sheep.