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Facilitation of the diving bradycardia (DB) after co‐activation of nasotrigeminal and peripheral chemoreceptor afferents (PC) in rat.
Author(s) -
Rozloznik Miroslav,
Dutschmann Mathias
Publication year - 2006
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.20.4.a375-a
Subject(s) - bradycardia , stimulation , microinjection , medicine , facilitation , anesthesia , antagonist , brainstem , chemistry , neuroscience , endocrinology , receptor , heart rate , biology , blood pressure
The diving response (DR) can be elicited by electrical stimulation of the trigeminal ethmoidal nerve (EN5). The DR was previously studied in the working‐heart brainstem preparation (WHBP) of rat and was characterised by protective apnoea, bradycardia and vasoconstriction (Dutschmann & Paton, 2002). There is still controversy about the PC modulation of the DB. Thus, we investigated expression and plasticity of the DB following simultaneous stimulation of EN5 (10s, 20Hz, 0.5–1mA) and PC (aortic injections of NaCN 0.01%). In the WHBP (n=13) repetitive co‐activation of EN5 and PC (n=10 trails) significantly (p<0.01) enhanced (n=8) or facilitated (n=5) the bradycardic response compared to EN5 stimulation alone. Repetitive co‐activations triggered a progressive sensitisation of the EN5 evoked DB. This progressive sensitisation of the diving bradycardia was more effective when co‐activation of EN5 and PC evoked a facilitation of the bradycardic response. The facilitation and progressive sensitisation of the DB was attenuated after microinjection of the H1‐receptor antagonist pyrilamine (10mM, n=6, p<0.05) into the nucleus of the solitary tract (NTS). We conclude that, the NTS is an important centre for the facilitation and plasticity of the DB and H1‐receptors play an important role in these adjustments. Funded by the BCCN Göttingen (01GQ0432) Lit: Dutschmann M & Paton JFR, Pflug. Arch. 444:227‐235, 2002