Abstract |
We studied the effects of mild hypothermia on cardiac contractility in isolated rabbit hearts perfused with Krebs-Henseleit solution according to the technique of Langendorff. Isovolumetric left ventricular pressure (LVP) was measured with a fluid-filled balloon. Hearts were paced after induction of atrioventricular block. At low heart rates ( < 30 bpm) mild hypothermia (cooling to 30 degrees C) induced a 32% increase in LVp (146.5 +/- 10 mm Hg at 30 degrees C vs 110.7 +/- 13 mm Hg at 37 degrees C) but this positive inotropic response was progressively lost by increasing heart rate. At pacing rates > or = 90 bpm, lower systolic LVP, higher diastolic LVP, and lower positive and negative LV dP/dt were obtained in hypothermic (93 +/- 12 mm Hg, 55 +/- 18 mm Hg, 584 +/- 137 mm Hg/s, and 323 +/- 57 mm Hg/s at 210 bpm, respectively) compared to normothermic hearts (123 +/- 4 mm Hg, 10 +/- 4 mm Hg, 1705 +/- 145.5 mm Hg/s, and 1155 +/- 78 mm Hg/s at 210 bpm, respectively.) The duration of mechanical diastole was reduced or suppressed in these hearts. Exposure to the beta-adrenoreceptor agonist, isoproterenol, improved this diastolic dysfunction during hypothermia and pacing at high rates, suggesting that the sarcoplasmic reticulum Ca2+ uptake might be involved. Our data are also consistent with an increase in myofilament Ca2+ sensitivity that is opposed by isoproterenol during hypothermia.
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Authors | M Mattheussen, K Mubagwa, H Van Aken, R Wusten, A Boutros, W Flameng |
Journal | Anesthesia and analgesia
(Anesth Analg)
Vol. 82
Issue 5
Pg. 975-81
(May 1996)
ISSN: 0003-2999 [Print] United States |
PMID | 8610909
(Publication Type: Comparative Study, Journal Article)
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Chemical References |
- Adrenergic beta-Agonists
- Cardioplegic Solutions
- Cardiotonic Agents
- Krebs-Henseleit solution
- Tromethamine
- Glucose
- Isoproterenol
- Calcium
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Topics |
- Actin Cytoskeleton
(drug effects, metabolism)
- Adrenergic beta-Agonists
(pharmacology)
- Animals
- Calcium
(metabolism)
- Cardiac Pacing, Artificial
- Cardioplegic Solutions
- Cardiotonic Agents
(pharmacology)
- Diastole
(drug effects)
- Glucose
- Heart Rate
- Hypothermia, Induced
- Isoproterenol
(pharmacology)
- Myocardial Contraction
(drug effects)
- Rabbits
- Sarcoplasmic Reticulum
(drug effects, metabolism)
- Tromethamine
- Ventricular Function, Left
- Ventricular Pressure
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