Focal acidosis in the pre-Botzinger complex area of awake goats induces a mild tachypnea

1 Department of Physiology, Medical College of Wisconsin, 2 Veterans Affairs Medical Center, and 3 Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin Submitted 21 April 2008 ; accepted in final form 6 November 2008 There are widespread chemosensitive areas in the brain with v...

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Published in:Journal of applied physiology (1985) 2009-01, Vol.106 (1), p.241-250
Main Authors: Krause, K. L, Forster, H. V, Davis, S. E, Kiner, T, Bonis, J. M, Pan, L. G, Qian, B
Format: Article
Language:English
Subjects:
Acidity
Acidosis - chemically induced
Acidosis - metabolism
Acidosis - physiopathology
Animals
Biological and medical sciences
Blood pressure
Brain
Carbon Dioxide
Cats
Chemoreceptor Cells - metabolism
Disease Models, Animal
Fundamental and applied biological sciences. Psychology
Goats
Heart rate
Hydrogen-Ion Concentration
Hypercapnia - chemically induced
Hypercapnia - metabolism
Hypercapnia - physiopathology
Microdialysis
Physiology
Pulmonary Ventilation
Respiratory Center - metabolism
Respiratory Center - physiopathology
Respiratory Mechanics
Respiratory system
Tidal Volume
Time Factors
Wakefulness
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Summary:1 Department of Physiology, Medical College of Wisconsin, 2 Veterans Affairs Medical Center, and 3 Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin Submitted 21 April 2008 ; accepted in final form 6 November 2008 There are widespread chemosensitive areas in the brain with varying effects on breathing. In the awake goat, microdialyzing (MD) 50% CO 2 at multiple sites within the medullary raphe increases pulmonary ventilation ( I ), blood pressure, heart rate, and metabolic rate ( O 2 ) (11), while MD in the rostral and caudal cerebellar fastigial nucleus has a stimulating and depressant effect, respectively, on these variables (17). In the anesthetized cat, the pre-Bötzinger complex (preBötzC), a hypothesized respiratory rhythm generator, increases phrenic nerve activity after an acetazolamide-induced acidosis (31, 32). To gain insight into the effects of focal acidosis (FA) within the preBötzC during physiological conditions, we tested the hypothesis that FA in the preBötzC during wakefulness would stimulate breathing, by increasing respiratory frequency (f). Microtubules were bilaterally implanted into the preBötzC of 10 goats. Unilateral MD of mock cerebral spinal fluid equilibrated with 6.4% CO 2 did not affect I , tidal volume (V T ), or f. Unilateral MD of 25 and 50% CO 2 significantly increased I and f by 10% ( P < 0.05, n = 10, 17 trials), but V T was unaffected. Bilateral MD of 6.4, 25, or 50% CO 2 did not significantly affect I , V T , or f ( P > 0.05, n = 6, 6 trials). MD of 80% CO 2 caused a 180% increase in f and severe disruptions in airflow ( n = 2). MD of any level of CO 2 did not result in any significant changes in mean arterial blood pressure, heart rate, or O 2 . Thus the data suggest that the preBötzC area is chemosensitive, but the responses to FA at this site are unique compared with other chemosensitive sites. breathing; chemosensitivity Address for reprint requests and other correspondence: K. L. Krause, 8701 Watertown Plank Rd., Milwaukee, WI 53226 (e-mail: klkrause{at}mcw.edu )
ISSN:8750-7587
1522-1601
DOI:10.1152/japplphysiol.90547.2008