Dopaminergic metabolism in carotid bodies and high altitude acclimatization in female rats
We tested the hypothesis that ovarian steroids stimulate breathing through a dopaminergic mechanism in the carotid bodies (CB). In ovariectomized female rats raised at sea level, domperidone, a peripheral D2 receptor antagonist, increased ventilation in normoxia (Ve : + 55%) and acute hypoxia (+ 32%). This effect disappeared after 10 daily injections of ovarian steroids (progesterone + estradiol). At high altitude (HA--3,600 m, IBBA, La Paz, Bolivia), neutered females had higher CB tyrosine hydroxylase activity (the rate-limiting enzyme for catecholamine synthesis: + 129%) and dopamine utilization (+ 150%), lower Ve (- 30%) and hypoxic ventilatory response (- 57%), and higher hematocrit (+ 18%) and hemoglobin concentration (+ 21%) than intact female rats. Consistent signs of arterial pulmonary hypertension (right ventricular hypertrophy) also appeared in ovariectomized females. None of these parameters was affected by gonadectomy in males. Our results show that ovarian steroids stimulate breathing by lowering a peripheral dopaminergic inhibitory drive. This process may partially explain the deacclimatization of postmenopausal women at high altitude.
| Main Authors: | , , , , , , |
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| Format: | Article biblioteca |
| Language: | English |
| Published: |
Am J Physiol Relulatory
2002-04
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| Subjects: | HIPOXIA, ESTEROIDES OVÁRICOS, MAL DE MONTAÑA CRÓNICO, |
| Online Access: | http://repositorio.umsa.bo/xmlui/handle/123456789/9690 |
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| Summary: | We tested
the hypothesis that ovarian steroids stimulate breathing
through a dopaminergic mechanism in the carotid bodies (CB). In
ovariectomized female rats raised at sea level, domperidone,
a peripheral D2 receptor antagonist, increased ventilation in
normoxia (Ve : + 55%) and acute hypoxia
(+ 32%). This effect disappeared after 10 daily injections of
ovarian steroids (progesterone + estradiol). At high altitude
(HA--3,600 m, IBBA, La Paz, Bolivia), neutered females had higher CB
tyrosine hydroxylase activity (the rate-limiting enzyme for
catecholamine synthesis: + 129%) and dopamine utilization
(+ 150%), lower Ve (- 30%) and hypoxic ventilatory response (- 57%), and higher hematocrit (+ 18%) and
hemoglobin concentration (+ 21%) than intact female rats. Consistent
signs of arterial pulmonary hypertension (right ventricular
hypertrophy) also appeared in ovariectomized females. None
of these parameters was affected by gonadectomy in males.
Our results show that ovarian steroids stimulate breathing
by lowering a peripheral dopaminergic inhibitory drive. This
process may partially explain the deacclimatization of postmenopausal women at high altitude. |
|---|