Open AccessBilateral sectioning of the anterior ethmoidal nerves does not eliminate the diving response in voluntarily diving rats
Author(s) -
Chotiyata Jill S.,
DiNovo Karyn M.,
McCulloch Paul F.
Publication year - 2013
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.1002/phy2.141
Subject(s) - medicine , reflex , heart rate , nose , bradycardia , anesthesia , stimulation , apnea , blood pressure , anatomy
The diving response is characterized by bradycardia, apnea, and increased peripheral resistance. This reflex response is initiated by immersing the nose in water. Because the anterior ethmoidal nerve ( AEN ) innervates the nose, our hypothesis was that intact AEN s are essential for initiating the diving response in voluntarily diving rats. Heart rate ( HR ) and arterial blood pressure ( BP a) were monitored using implanted biotransmitters. Sprague‐Dawley rats were trained to voluntarily swim 5 m underwater. During diving, HR decreased from 480 ± 15 to 99 ± 5 bpm and BP a increased from 136 ± 2 to 187 ± 3 mmHg. Experimental rats ( N = 9) then received bilateral AEN sectioning, while Sham rats ( N = 8) did not. During diving in Experimental rats 7 days after AEN surgery, HR decreased from 478 ± 13 to 76 ± 4 bpm and BP a increased from 134 ± 3 to 186 ± 4 mmHg. Responses were similar in Sham rats. Then, during nasal stimulation with ammonia vapors in urethane‐anesthetized Experimental rats, HR decreased from 368 ± 7 to 83 ± 4 bpm, and BP a increased from 126 ± 7 to 175 ± 4 mmHg. Responses were similar in Sham rats. Thus, 1 week after being sectioned the AEN s are not essential for initiating a full cardiorespiratory response during both voluntary diving and nasal stimulation. We conclude that other nerve(s) innervating the nose are able to provide an afferent signal sufficient to initiate the diving response, although neuronal plasticity within the medullary dorsal horn may be necessary for this to occur.