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Adaptation of the Baroreflex at the Dorsomedial Nucleus of Solitary Tract
Author(s) -
Tang Xiaorui Tang,
Freet Christopher S,
Stoner James
Publication year - 2011
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.25.1_supplement.1027.15
Subject(s) - baroreflex , baroreceptor , stimulation , adaptation (eye) , solitary tract , medicine , anesthesia , nucleus , cardiology , neuroscience , blood pressure , biology , heart rate , brainstem
The set point and operating range of the baroreflex adapt to prevailing arterial pressure (AP). Although the adaptation feature of the baroreceptors is well recognized, whether there are central components remains controversial and data directly evaluating central adaptation over an extended period (> 30 hrs) are especially limited. The neuromuscular blocked (NMB) rat preparation, however, provides a unique opportunity in which to investigate this phenomenon. In four NMB Sprague‐Dawley female rats, we evaluated central adaptation to prolonged continuous aortic depressor nerve (ADN) electrical stimulation at the dorsomedial nucleus of solitary tract (dmNTS). A‐ and C‐ fibers were identified in the ADN by their distinct current thresholds and different latencies to the dmNTS (10–30 μA for A, 20–50 μA for C). A‐ and C‐fiber evoked responses (ERs) to continuous ADN stimulation (10 Hz, 300 μs, at an intensity eliciting 10–40 mmHg AP reduction) were stably recorded at the dmNTS for up to 67 hours; AP was recorded throughout the experiment. We did not detect adaptation in the magnitude of hourly ensemble averaged A‐, C‐, and A+C‐fiber ERs at the dmNTS, but adaptation was detected in the magnitude of hourly averaged systolic AP in two of the four rats (Rat1: adapting rate: 0.09 mmHg/hr, p< 0.05; Rat2: adapting rate: 0.19 mmHg/hr, p< 0.05). Supported by a PA State Tobacco Settlement Award.