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Influence of estrous cycle on the ventilatory responses to hypercapnia and hypoxia in rats
Author(s) -
Gargaglioni Luciane H,
Marques Danuzia A,
Batalhao Marcelo E.,
Carvalho Debora,
Szawka Raphael E.,
AnselmoFranci Janete,
Bicego Kenia C.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.847.17
The present study examined the hypoxic (HVR) and hypercapnic (HCVR) respiratory responses of female rats on different days of estrous cycle, (estrus, diestrus, proestrus) and in ovariectomized rats. Only rats showing at least 5 consecutive estrous cycles were included. Pulmonary ventilation (VE) and body temperature (Tb) were measured followed by 30 min of hypercapnic exposure (7% CO 2 in air) and hypoxia (5% O 2 ) in unanesthetized animals. Under resting conditions, there is no difference in V E between animals. Tb was greater on estrus compared to the other groups during air and 7%CO 2 . Hypoxia caused an increase in VE and a drop in Tb in all groups, but the HVR was smaller on diestrus (717.8 ± 41.5 mL/Kg/min), proestrus (712.1 ± 34.1 mL/Kg/min), and in ovariectomized (516.6 ± 13.4 mL/Kg/min) rats compared to estrus (1213.2 ± 284 mL/Kg/min), due to a reduced tidal volume. Hypoxia‐induced drop in Tb was not different between groups. HCVR was also reduced on diestrus (978.6 ± 88.9 mL/Kg/min), proestrus (1056.7 ± 108.9 mL/Kg/min), and in ovariectomized rats (717.3 ± 71.2 mL/Kg/min) compared to estrus (1336.9 ± 253 mL/Kg/min), due to a decreased tidal volume. Thus, different days of the estrous cycle influence the HVR and HCVR in rats, acting on tidal volume. Additionally, Tb is increased in estrous cycle during normoxia normocapnia and hypercapnia but is not different in hypoxic challenge. Financial Support: FAPESP and CNPq.