TY - JOUR
T1 - Changes in cardiovascular β-adrenoceptor responses during hypothermia
AU - Han, Young Soo
AU - Tveita, Torkjel
AU - Kondratiev, Timofei V.
AU - Prakash, Y. S.
AU - Sieck, Gary C.
N1 - Funding Information:
This study was supported by the following grants: The Laerdal Foundation for Acute Medicine and the Norwegian Anesthesiological Society to T. Tveita. A clinical research grant and early career development award to Y.S. Prakash. Y.S. Han was supported by Mayo Graduate School.
PY - 2008/12
Y1 - 2008/12
N2 - The purpose of this study was to determine cardiovascular β-adrenergic responses during hypothermia. In the present study, we used isoproterenol (Iso), a nonselective, potent β-adrenoceptor agonist, well known for its positive chronotropic and inotropic pharmacologic actions at normothermia. Rats were instrumented to measure mean arterial pressure (MAP) and left ventricular (LV) pressure-volume changes using a Millar pressure-volume conductance catheter. Core temperature was manipulated from 37 (normothermia) to 24 °C (hypothermia) and back to 37 °C (rewarming) using both internal and external heat exchangers. During cooling at each temperature (33, 30, 27, and 24 °C), central hemodynamic variables and MAP were measured while intravenously infusing Iso (doses of 1.7, 5, 10, and 20 ng/min). Seven animals underwent all phases of the protocol. At normothermia Iso infusion resulted in a significant, dose-dependent increase in heart rate (HR), stroke volume (SV), cardiac output (CO), LV dP/dtmax (left ventricular maximum derivative of systolic pressure over time) but no change in MAP. During cooling Iso infusion caused no dose-dependent change in any of the hemodynamic variables. After rewarming, baseline HR and LV dP/dtmax were increased, whereas SV was significantly reduced when compared with their pre-hypothermic baseline values. This study shows that physiological cardiovascular responses mediated by the β-adrenoceptor are significantly diminished during core hypothermia.
AB - The purpose of this study was to determine cardiovascular β-adrenergic responses during hypothermia. In the present study, we used isoproterenol (Iso), a nonselective, potent β-adrenoceptor agonist, well known for its positive chronotropic and inotropic pharmacologic actions at normothermia. Rats were instrumented to measure mean arterial pressure (MAP) and left ventricular (LV) pressure-volume changes using a Millar pressure-volume conductance catheter. Core temperature was manipulated from 37 (normothermia) to 24 °C (hypothermia) and back to 37 °C (rewarming) using both internal and external heat exchangers. During cooling at each temperature (33, 30, 27, and 24 °C), central hemodynamic variables and MAP were measured while intravenously infusing Iso (doses of 1.7, 5, 10, and 20 ng/min). Seven animals underwent all phases of the protocol. At normothermia Iso infusion resulted in a significant, dose-dependent increase in heart rate (HR), stroke volume (SV), cardiac output (CO), LV dP/dtmax (left ventricular maximum derivative of systolic pressure over time) but no change in MAP. During cooling Iso infusion caused no dose-dependent change in any of the hemodynamic variables. After rewarming, baseline HR and LV dP/dtmax were increased, whereas SV was significantly reduced when compared with their pre-hypothermic baseline values. This study shows that physiological cardiovascular responses mediated by the β-adrenoceptor are significantly diminished during core hypothermia.
KW - Cardiovascular function
KW - Cold
KW - Hypothermia
KW - Isoproterenol
KW - Rat
KW - Temperature
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U2 - 10.1016/j.cryobiol.2008.09.006
DO - 10.1016/j.cryobiol.2008.09.006
M3 - Article
C2 - 18834873
AN - SCOPUS:56449092053
SN - 0011-2240
VL - 57
SP - 246
EP - 250
JO - Cryobiology
JF - Cryobiology
IS - 3
ER -