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Effects of sex hormones on metabolic rate, ventilation and respiratory‐related upper airway muscle activities in female rats
Author(s) -
Richardson Patrick A.,
Fregosi Ralph F.,
Hoyer Patricia B,
Bailey E. Fiona
Publication year - 2009
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.23.1_supplement.1010.3
Subject(s) - ventilation (architecture) , tidal volume , hypercapnia , medicine , respiratory system , hyperoxia , exhalation , respiratory minute volume , anesthesia , endocrinology , plethysmograph , respiratory rate , lung , heart rate , blood pressure , mechanical engineering , engineering
We tested the hypothesis that changes in sex hormones in female rats resulting from ovarian failure induced by exposure to 4‐vinylcyclohexene diepoxide (VCD) alter metabolism, ventilation and respiratory‐related upper airway muscle activities. Two groups of Fischer‐344 female rats were used, one group injected daily with VCD, 80 mg/kg i.p. for 25 days (N=5), the other an age‐matched control group (N=5) injected daily with sesame oil. We obtained in‐vivo measures of VCO 2 /VO 2 , tidal volume (V T ) and breathing frequency (F R ) using a sealed whole‐body plethysmography chamber. In the same animals, we recorded EMG activities of hyoglossus (HG) and genioglossus (GG) muscles and esophageal pressure (Pes) under urethane anesthesia in hyperoxia (FICO 2 =0) and hyperoxic hypercapnia (FICO 2 =0.03, 0.06, 0.09, 0.12 balance O 2 ). Preliminary data reveal increased basal VO 2, VCO 2 and the ratio of VCO 2 /VO 2 for VCD treated rats relative to age‐matched controls. Measures of ventilation and whole muscle EMG were comparable for the two groups in hyperoxia whereas VCD treated rats exhibited a trend toward higher V T and F R and greater average GG and HG EMG activities in hyperoxic hypercapnia relative to the age‐matched controls. These studies provide preliminary insights into metabolic rate, ventilation and respiratory‐related upper airway activities as a function of ovarian failure in age‐matched controls.