Altered cardiac β1 responsiveness in hyperthermic older adults
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Altered cardiac β1 responsiveness in hyperthermic older adults. / Fischer, Mads; Moralez, Gilbert; Sarma, Satyam; MacNamara, James P; Cramer, Matthew N; Huang, Mu; Romero, Steven A; Hieda, Michinari; Shibasaki, Manabu; Ogoh, Shigehiko; Crandall, Craig G.
I: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology, Bind 323, Nr. 4, 2022, s. R581-R588.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Altered cardiac β1 responsiveness in hyperthermic older adults
AU - Fischer, Mads
AU - Moralez, Gilbert
AU - Sarma, Satyam
AU - MacNamara, James P
AU - Cramer, Matthew N
AU - Huang, Mu
AU - Romero, Steven A
AU - Hieda, Michinari
AU - Shibasaki, Manabu
AU - Ogoh, Shigehiko
AU - Crandall, Craig G
N1 - CURIS 2022 NEXS 255
PY - 2022
Y1 - 2022
N2 - Introduction: Compared to younger adults, passive heating induced increases in cardiac output are attenuated by ~50% in older adults. This attenuated response may be associated with older individuals' inability to maintain stroke volume through ionotropic mechanisms and/or through altered chronotropic mechanisms.Purpose: To identify the interactive effect of age and hyperthermia on cardiac responsiveness to dobutamine induced cardiac stimulation.Methods: 11 Young (26±4 yr) and 8 Older (68±5 yr) participants underwent a normothermic and a hyperthermic (baseline core temperature +1.2°C) trial on the same day. In both thermal conditions, after baseline measurements, intravenous dobutamine was administered for 12 min at 5 µg/kg/min, followed by 12 min at 15 µg/kg/min. Primary measurements included echocardiography-based assessments of cardiac function, gastrointestinal and skin temperatures, heart rate and mean arterial pressure.Results: Heart rate responses to dobutamine were similar between groups in both thermal conditions (P > 0.05). The peak systolic mitral annular velocity (S'), i.e., an index of left ventricular longitudinal systolic function, was similar between groups for both thermal conditions at baseline. While normothermic, the increase in S' between groups was similar with dobutamine administration. However, while hyperthermic, the increase in S' was attenuated in the Older participants with dobutamine (P < 0.001).Conclusion: Healthy, older individuals show attenuated inotropic, but maintained chronotropic responsiveness to dobutamine administration during hyperthermia. These data suggests that older individuals have a reduced capacity to increase cardiomyocyte contractility, estimated by changes in S', via β1-adrenergic mechanisms while hyperthermic.
AB - Introduction: Compared to younger adults, passive heating induced increases in cardiac output are attenuated by ~50% in older adults. This attenuated response may be associated with older individuals' inability to maintain stroke volume through ionotropic mechanisms and/or through altered chronotropic mechanisms.Purpose: To identify the interactive effect of age and hyperthermia on cardiac responsiveness to dobutamine induced cardiac stimulation.Methods: 11 Young (26±4 yr) and 8 Older (68±5 yr) participants underwent a normothermic and a hyperthermic (baseline core temperature +1.2°C) trial on the same day. In both thermal conditions, after baseline measurements, intravenous dobutamine was administered for 12 min at 5 µg/kg/min, followed by 12 min at 15 µg/kg/min. Primary measurements included echocardiography-based assessments of cardiac function, gastrointestinal and skin temperatures, heart rate and mean arterial pressure.Results: Heart rate responses to dobutamine were similar between groups in both thermal conditions (P > 0.05). The peak systolic mitral annular velocity (S'), i.e., an index of left ventricular longitudinal systolic function, was similar between groups for both thermal conditions at baseline. While normothermic, the increase in S' between groups was similar with dobutamine administration. However, while hyperthermic, the increase in S' was attenuated in the Older participants with dobutamine (P < 0.001).Conclusion: Healthy, older individuals show attenuated inotropic, but maintained chronotropic responsiveness to dobutamine administration during hyperthermia. These data suggests that older individuals have a reduced capacity to increase cardiomyocyte contractility, estimated by changes in S', via β1-adrenergic mechanisms while hyperthermic.
KW - Faculty of Science
KW - Beta-adrenergic
KW - Hyperthermia
KW - Heat stress
KW - Aging
U2 - 10.1152/ajpregu.00040.2022
DO - 10.1152/ajpregu.00040.2022
M3 - Journal article
C2 - 36094450
VL - 323
SP - R581-R588
JO - American Journal of Physiology
JF - American Journal of Physiology
SN - 0363-6119
IS - 4
ER -
ID: 319526497