| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
2 Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin, USA
3 Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA; Zablocki VA Medical Center, Milwaukee, Wisconsin, USA
* To whom correspondence should be addressed. E-mail: mhodges46{at}hotmail.com.
Focal acidosis (FA) at single sites in the medullary raphe increases breathing during wakefulness (goats) and sleep (rats)(9, 22). Our aim was to determine the effects of FA at multiple medullary raphe sites in awake goats. FA at single (n=7) or multiple (n=6) sites was created through chronically implanted microtubules into midline raphe regions by microdialysis (MD) of mock cerebral spinal fluid (mCSF) equilibrated with 6.4% (pH=7.3), 50% (pH=6.5) or 80% (pH=6.3) CO2. We have previously shown that MD with a mCSF pH of 6.5 or 6.3, raphe tissue pH decreases by 0.1 and 0.18 respectively 200 µm from the MD site. These changes compare to the 0.06 decrease in the raphe pH with 7.5% inspired CO2 (11). MD with 6.4% CO2 at single or multiple sites had no effect on inspiratory flow (VI), tidal volume (VT), frequency (f), ventilatory drive (VT/TI), heart rate (HR), blood pressure or metabolic rate (VO2). MD at single sites with 80% CO2 increased VI (16.3 ± 4.9%), VT (16.9 ± 7.2%), and f (5.5 ± 1.5%) above control (P < 0.05). FA at multiple sites with either 50% or 80% CO2 increased VI by 18.4 ± 6.8% and 30.1 ± 7.4%, respectively (P < 0.05), where FA with 80% CO2 at multiple sites additionally increased VT, VT/TI, HR, VO2 and VCO2 (P < 0.05), highlighting the influence of the raphe on other physiologic functions in addition to breathing. We also noted hyperventilation (-2 mmHg, P < 0.005) with MD with 80% CO2 at multiple sites indicating that acidification has an effect on breathing independent of increasing metabolic rate. We conclude that: 1) under physiologic conditions the increase in breathing resulting from focal acidification is dependent upon the degree of acidification by increasing both CO2/H+, or the number of acidic foci and we speculate that the ventilatory response to inspired CO2 reflects a cumulative effect of stimulation of multiple chemoreceptor sites. Finally, we conclude that chemoreceptor stimulation affects multiple physiologic variables in addition to breathing.
This article has been cited by other articles:
|
|
 |
|
  E. Nattie and A. Li Central chemoreception is a complex system function that involves multiple brain stem sites J Appl Physiol, April 1, 2009; 106(4): 1464 - 1466. [Full Text] [PDF]
|
|
|
|
|
|
K. L. Krause, H. V. Forster, S. E. Davis, T. Kiner, J. M. Bonis, L. G. Pan, and B. Qian Focal acidosis in the pre-Botzinger complex area of awake goats induces a mild tachypnea J Appl Physiol, January 1, 2009; 106(1): 241 - 250. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. G. Guyenet The 2008 Carl Ludwig Lecture: retrotrapezoid nucleus, CO2 homeostasis, and breathing automaticity J Appl Physiol, August 1, 2008; 105(2): 404 - 416. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. B. Dias, A. Li, and E. Nattie Focal CO2 dialysis in raphe obscurus does not stimulate ventilation but enhances the response to focal CO2 dialysis in the retrotrapezoid nucleus J Appl Physiol, July 1, 2008; 105(1): 83 - 90. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Li and E. Nattie Serotonin transporter knockout mice have a reduced ventilatory response to hypercapnia (predominantly in males) but not to hypoxia J. Physiol., May 1, 2008; 586(9): 2321 - 2329. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. G. Guyenet, R. L. Stornetta, and D. A. Bayliss Retrotrapezoid nucleus and central chemoreception J. Physiol., April 15, 2008; 586(8): 2043 - 2048. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. R. Hodges, G. J. Tattersall, M. B. Harris, S. D. McEvoy, D. N. Richerson, E. S. Deneris, R. L. Johnson, Z.-F. Chen, and G. B. Richerson Defects in Breathing and Thermoregulation in Mice with Near-Complete Absence of Central Serotonin Neurons J. Neurosci., March 5, 2008; 28(10): 2495 - 2505. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. K. Mulkey, D. L. Rosin, G. West, A. C. Takakura, T. S. Moreira, D. A. Bayliss, and P. G. Guyenet Serotonergic Neurons Activate Chemosensitive Retrotrapezoid Nucleus Neurons by a pH-Independent Mechanism J. Neurosci., December 19, 2007; 27(51): 14128 - 14138. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. B. Dias, T. B. Nucci, L. O. Margatho, J. Antunes-Rodrigues, L. H. Gargaglioni, and L. G. S. Branco Raphe magnus nucleus is involved in ventilatory but not hypothermic response to CO2 J Appl Physiol, November 1, 2007; 103(5): 1780 - 1788. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Nattie and A. Li Neurokinin-1 receptor-expressing neurons in the ventral medulla are essential for normal central and peripheral chemoreception in the conscious rat J Appl Physiol, December 1, 2006; 101(6): 1596 - 1606. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Li, S. Zhou, and E. Nattie Simultaneous inhibition of caudal medullary raphe and retrotrapezoid nucleus decreases breathing and the CO2 response in conscious rats J. Physiol., November 15, 2006; 577(1): 307 - 318. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. S. Moreira, A. C. Takakura, E. Colombari, and P. G. Guyenet Central chemoreceptors and sympathetic vasomotor outflow J. Physiol., November 15, 2006; 577(1): 369 - 386. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. F. Martino, M. R. Hodges, S. Davis, C. Opansky, L. G. Pan, K. Krause, B. Qian, and H. V. Forster CO2/H+ chemoreceptors in the cerebellar fastigial nucleus do not uniformly affect breathing of awake goats J Appl Physiol, July 1, 2006; 101(1): 241 - 248. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Sood, E. Raddatz, X. Liu, H. Liu, and R. L. Horner Inhibition of serotonergic medullary raphe obscurus neurons suppresses genioglossus and diaphragm activities in anesthetized but not conscious rats J Appl Physiol, June 1, 2006; 100(6): 1807 - 1821. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. C. T. Takakura, T. S. Moreira, E. Colombari, G. H. West, R. L. Stornetta, and P. G. Guyenet Peripheral chemoreceptor inputs to retrotrapezoid nucleus (RTN) CO2-sensitive neurons in rats J. Physiol., April 15, 2006; 572(2): 503 - 523. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. G. Guyenet, D. K. Mulkey, R. L. Stornetta, and D. A. Bayliss Regulation of Ventral Surface Chemoreceptors by the Central Respiratory Pattern Generator J. Neurosci., September 28, 2005; 25(39): 8938 - 8947. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. B. Richerson Re: Retrotrapezoid nucleus: a litmus test for the identification of central chemoreceptors Exp Physiol, May 1, 2005; 90(3): 253 - 257. [Full Text] [PDF]
|
|
|
|
|
|
G. B. Richerson, W. Wang, M. R. Hodges, C. I. Dohle, and A. Diez-Sampedro Homing in on the specific phenotype(s) of central respiratory chemoreceptors Exp Physiol, May 1, 2005; 90(3): 259 - 266. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. R. Hodges, C. Opansky, B. Qian, S. Davis, J. M. Bonis, K. Krause, L. G. Pan, and H. V. Forster Carotid body denervation alters ventilatory responses to ibotenic acid injections or focal acidosis in the medullary raphe J Appl Physiol, April 1, 2005; 98(4): 1234 - 1242. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
