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Cardiac chronotropic and inotropic responses evoked from right or left sides of dorsomedial hypothalamus
Author(s) -
Xavier Carlos Henrique,
Beig Mirza Irfan,
Ianzer Danielle,
Fontes Marco Peliky,
Nalivaiko Eugene
Publication year - 2010
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.24.1_supplement.1019.20
Subject(s) - chronotropic , medicine , inotrope , atenolol , endocrinology , heart rate , cardiology , blood pressure
We previously reported a functional asymmetry in the descending cardiovascular pathways from dorsomedial hypothalamus (DMH). Right DMH is critical for expressing full tachycardic responses to stress, and its activation evokes more pronounced tachycardia compared to left DMH. We next evaluated the cardiac chronotropic and inotropic responses evoked by right (R) or left (L) sides of DMH. In anesthetized adult male Wistar rats (n=7) we compared changes in LVP, LVdP/dt, ECG, and AP evoked by a microinjection of a GABAA antagonist bicuculline (40pmol/100nl) into L‐ or R‐DMH. R‐DMH activation evoked greater increases in HR (Δ: R 108±12 vs. L 63±9bpm), LVP (Δ: R 43±10 vs. L 22±5mmHg) and LVdP/dtpeak (Δ: R 106±17 vs. L 77±15%) compared to the L‐DMH activation (P<0.05 for all), whereas pressor responses were similar for both sides. R‐DMH activation provoked greater number of ectopic beats (Δ: R 16±10 vs. L 7±3 ectopic beats/10min, P<0.05). No differences were found in ECG intervals after L‐ or R‐DMH activation. Atenolol (2mg/kg i.v.) blocked cardiac chronotropic and inotropic responses evoked by unilateral L‐ or R‐DMH activation. We conclude that right DMH has dominant effects on cardiac inotropic and chronotropic changes, and that it may be involved in the genesis of cardiac arrhythmias. Support: FAPEMIG‐PPM and CNPq.