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

¹Department of Physiology, Medical College of Wisconsin, ²Veterans Affairs Medical Center, and ³Department 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% CO₂ at multiple sites within the medullary raphe increases pulmonary ventilation (I), blood pressure, heart rate, and metabolic rate (O₂) (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% CO₂ did not affect I, tidal volume (VT), or f. Unilateral MD of 25 and 50% CO₂ significantly increased I and f by 10% (P < 0.05, n = 10, 17 trials), but VT was unaffected. Bilateral MD of 6.4, 25, or 50% CO₂ did not significantly affect I, VT, or f (P > 0.05, n = 6, 6 trials). MD of 80% CO₂ caused a 180% increase in f and severe disruptions in airflow (n = 2). MD of any level of CO₂ did not result in any significant changes in mean arterial blood pressure, heart rate, or O₂. 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

This article has been cited by other articles:

				K. L. Krause, S. E. Neumueller, B. D. Marshall, T. Kiner, J. M. Bonis, L. G. Pan, B. Qian, and H. V. Forster {micro}-Opioid receptor agonist injections into the presumed pre-Botzinger complex and the surrounding region of awake goats do not alter eupneic breathing J Appl Physiol, November 1, 2009; 107(5): 1591 - 1599. [Abstract] [Full Text] [PDF]