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Hemodynamic effects of intravenous amiodarone in conscious or anesthetized rats.
Author(s) -
Filho Valter Joviniano Santana,
Rodrigues Fernanda Luciano,
Oliveira Mauro,
Silva Valdo Jose Dias,
Salgado Helio Cesar,
Fazan Rubens
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.20.5.a1408-c
Intravenous amiodarone (AM) is efficient in suppressing cardiac arrhythmias, however, its hemodynamics effects are complex and poorly understood. We evaluated hemodynamic effects of AM in conscious or anesthetized rats. 24 h after receiving femoral catheters and Doppler flow probe around abdominal aorta, conscious rats had blood pressure (BP) and hindquarter flow recorded before and after AM (50 mg/kg, iv, n=8) or vehicle (n=8). Two groups of rats were treated with losartan (10 mg/kg, iv, n=9) or vasopressin receptor antagonist (AVPant: 10 μg/kg, iv, n=8) before AM. A 3rd group received prazosin (1 mg/kg, iv) 20 min after AM (n=8) or vehicle (n=8). AM caused a fall in BP (96±2 to 69±2 mmHg) with partial recover in 10–20 min. AM also induced a bradycardia (386±7 to 279±8 bpm) throughout the experiment. Hindquarter resistance was reduced (−46±5%) immediately after AM, returning to basal level in 5–10 min. Pre‐treatment with losartan or AVPant did not affect hemodynamic response to AM. Prazosin induced a smaller fall in hindquarter resistance in rats pre‐treated with AM (9±3%) as compared to rats pre‐treated with vehicle (16±4%). BP and cardiac output (CO) measurements were performed also in urethane anesthetized rats, before and after AM (n=8) or vehicle (n=8). Total peripheral resistance (BP/CO) was reduced from 0.51±0.05 to 0.27±0.04 mmHg/mL/min immediately after AM, returning to basal level in 10–15 min. AM causes hypotension, bradycardia and peripheral vasodilatation. The vasodilatation is transitory, and the recovery of peripheral resistance does not involve a role played by alpha‐adrenergic, angiotensin or vasopressin receptors.