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Thermal prolongation of the Hering‐Breuer inflation reflex in neonatal rats depends on an adenosinergic mechanism in the brainstem
Author(s) -
Arnal Ashley V.,
Gore Julie L.,
Bartlett Donald,
Leiter J. C.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.1090.6
Subject(s) - reflex , plethysmograph , anesthesia , medicine , apnea , caffeine , brainstem
The Hering‐Breuer (HB) inflation reflex prolongs expiratory duration (TE), and elevated body temperature increases this prolongation in neonatal rats. The neurophysiological mechanisms of this thermal sensitivity have not been studied, but the thermal sensitivity of the HB reflex is similar to that of the laryngeal chemoreflex (LCR). Therefore, we tested the hypothesis that blocking adenosine receptors with caffeine, which shortens the LCR, would blunt the thermal prolongation of apnea associated with the HB reflex. Neonatal rats (P4 to P20) were anesthetized briefly to administer intracisternal caffeine (2 microL of 10 mM) or vehicle, allowed to wake up and studied in a head out plethysmograph. The HB reflex was elicited at body temperatures of 32 and 36 degrees C by decreasing the plethysmographic pressure (−5 cm H2O) at the end of inspiration. The inflation was maintained until the next inspiratory effort, and we measured the apneic interval between inspiratory efforts. Intracisternal injection of caffeine shortened the HB reflex apnea at the higher body temperature, and the shortening was greater in younger animals. Support: grants 36379 & 42707 from the NICHD.