American journal of physiology. Heart and circulatory physiology
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Am. J. Physiol. Heart Circ. Physiol. · Jun 2010
The heart rate response to spontaneous arousal from sleep is reduced in children with Down syndrome referred for evaluation of sleep-disordered breathing.
Arousal from sleep in healthy adults is associated with a large, transient increase in heart rate (HR). Individuals with Down syndrome (DS) have attenuated cardiovascular responses to autonomic tests during wakefulness. We tested the hypothesis that the HR response to arousal from sleep is reduced in children with DS and obstructive sleep apnea (OSA) compared with healthy children. ⋯ Post hoc analysis revealed that HR in the DS group was significantly lower than both control groups at 1-4 s in NREM and at 4 to 5 s in REM (P < 0.05 for all). In conclusion, the HR response to spontaneous arousal from sleep is reduced in children with DS and OSA compared with healthy children. This attenuated cardiovascular response could be due to reduced sympathetic activation or blunted vagal withdrawal and may have implications for the child with DS and OSA.
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Am. J. Physiol. Heart Circ. Physiol. · Jun 2010
Akt1 genetic deficiency limits hypothermia cardioprotection following murine cardiac arrest.
Therapeutic hypothermia (TH) cardioprotection has recently been associated with increased Akt signaling in a rat model of cardiac arrest. However, it is not known whether Akt is required for this beneficial effect of TH. We used a mouse model of cardiac arrest demonstrating TH cardioprotection to study the response of mice deficient in an Akt1 allele. ⋯ TH-associated alterations in Akt phosphorylation, stroke volume, heart rate, and cardiac output were abrogated in Akt1(+/-) animals. In conclusion, TH improves post-ROSC cardiac function and increases Akt phosphorylation in WT, but not Akt1(+/-), mice. The Akt1 isoform appears necessary for TH-mediated cardioprotection.