Document Detail

Involvement of cholinergic mechanisms in the central control of respiration in the cane toad, Bufo marinus.
MedLine Citation:
PMID:  11282326     Owner:  NLM     Status:  MEDLINE    
Chemical substrates, central sites and central mechanisms underlying the regulation of breathing in lower vertebrates have not been well characterized. The present study was undertaken to determine the effect of pH changes and cholinergic agents on the central control of respiration in the cane toad, Bufo marinus. Adult toads were anesthetized, catheterized and unidirectionally ventilated before exposing the brainstem. An airtight buccal cannula was also inserted through the tympanum to record buccal pressure. The animal was decerebrated, anesthetic removed and the responses to pH changes of solutions bathing the ventral surface of the medulla (VSM) were tested by superfusing the VSM with mock cerebrospinal fluid (mCSF) of pH 7.8-normal, 7.2-acidic and 8.4-basic. The acidic solution increased respiratory activity, the basic solution decreased activity and the normal solution had no effect. In addition, cholinergeric agents (acetylcholine-ACh, physostigmine-Phy, nicotine-Nic, and atropine-Atr) dissolved in mCSF were applied bilaterally onto the VSM using filter paper pledgets. ACh, Phy and Nic increased episodic breathing frequency by 14.3+/-9.7, 9.4+/-5.4 and 29.1+/-11.8 %, respectively, whereas, Atr caused a decrease (-26.6+/-16.6%). These agents had no effect on blood pressure. It is therefore, concluded that the VSM is pH sensitive and a cholinergic mechanism is involved in the central modulation of respiration in Bufo.
L L Kennedy; C C Aguwa; J E Rives; D G Bernard
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Comparative biochemistry and physiology. Part A, Molecular & integrative physiology     Volume:  128     ISSN:  1095-6433     ISO Abbreviation:  Comp. Biochem. Physiol., Part A Mol. Integr. Physiol.     Publication Date:  2001 Apr 
Date Detail:
Created Date:  2001-04-03     Completed Date:  2001-08-09     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  9806096     Medline TA:  Comp Biochem Physiol A Mol Integr Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  837-49     Citation Subset:  IM    
Department of Biology, University of Texas at Arlington, 501 Nedderman Drive, Box 19498, Arlington, TX 76019, USA.
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MeSH Terms
Acetylcholine / metabolism,  pharmacology
Atropine / metabolism,  pharmacology
Bufo marinus / physiology*
Cholinergic Agents / pharmacology
Decerebrate State
Hydrogen-Ion Concentration
Medulla Oblongata / drug effects,  physiology
Nicotine / metabolism,  pharmacology
Physostigmine / metabolism,  pharmacology
Reg. No./Substance:
0/Cholinergic Agents; 51-55-8/Atropine; 51-84-3/Acetylcholine; 54-11-5/Nicotine; 57-47-6/Physostigmine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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