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Cardiovascular deconditioning augments baseline breathing as well as peripheral and central chemoreflex responses
Author(s) -
Zhou Zijin,
King T Luise,
Kline David D,
Heesch Cheryl M,
Hasser Eileen M
Publication year - 2012
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.26.1_supplement.702.14
Subject(s) - hypercapnia , tidal volume , ventilation (architecture) , medicine , control of respiration , hypoxia (environmental) , hypoxic ventilatory response , respiratory minute volume , anesthesia , peripheral chemoreceptors , baroreflex , respiratory rate , peripheral , cardiology , heart rate , respiratory system , blood pressure , chemistry , stimulation , carotid body , oxygen , mechanical engineering , organic chemistry , engineering
Cardiovascular deconditioning (CVD) results in altered central autonomic regulation including baroreflex dysfunction. However, little is known regarding the effects of CVD on chemoreflex function. We hypothesized that CVD increases baseline breathing and peripheral (hypoxic ventilatory response, HVR) and central chemoreflex responses (hypercapnic ventilatory response, HCVR). Hindlimb unloaded (HU; 2 wks) rats were used to simulate CVD. Breathing and O2 saturation were evaluated (5 min) during normoxia, increasing severity of hypoxia (12%O2, 10%O2, 8%O2), and hypercapnia (5%CO2) to determine HVR and HCVR. Under normoxic conditions, O2 saturation and breathing rate were similar while tidal volume index (VT) was increased in HU vs. control rats. Increasing the intensity of hypoxia produced a progressive decrease in O2 saturation that was greater in HU vs. control rats. Hypoxia produced an intensity dependent augmentation of breathing rate, VT and minute ventilation (VE) in both groups. Increases in breathing rate during hypoxia were similar between groups. However, the VT response was augmented in HU rats. Hypercapnia also increased VE in both groups and VE was greater in HU vs. control rats due to increased VT. Preliminary data suggest that CVD due to HU increases VT under basal conditions. Furthermore, HU enhances the peripheral chemoreflex HVR and central chemoreflex HCVR due to increased VT. HL55306