Data presentation

Sequential 11 day data of a murin model for hindlimb suspension subdivided as a 3-day control period, a 5-day suspension period, a 2-day recovery period and a brief re-suspension. Physiological parameters (Sys(mmHg):Pressure, Dia(mmHg):Pressure, Mean(mmHg):Pressure, +dP/dt(mmHg/ms):Pressure, -dP/dt(mmHg/ms):Pressure, HR(bpm):Pressure, HR(bpm):ECG, RR-I(ms):ECG, R-H(mV):ECG, QRS(ms):ECG, QT-I(ms):ECG, QTcb(ms):ECG, QTcf(ms):ECG, QTcv(ms):ECG, T_NPMN(Celsius):Temp, A_NPMN(Counts):Activity) are provided as two-hour time bins datasets from HD-X11 transmitters (Data Science International®, DSI, Saint Paul MN, USA) and telemetric receivers (RPC-1 PhysioTelTM Receivers, DSI).

Research purpose It remains unclear how the autonomic nervous system adapts to short and long duration missions. On board studies are limited due to high costs and difficulties in obtaining data during missions; therefore, our data is mainly from ground-based models. Yet, the hemodynamic and autonomic responses during simulated microgravity using these models remain controversial. The controversy is likely rooted in the heterogeneity between species, the differences in both the duration of microgravity exposure as well as the choice of time points for recorded measures. We sought to clarify various controversial aspects of these forms of experiments by devising a murine hindlimb unloading (HU) model with continuous monitoring of relevant parameters. We aimed to define the kinetics of cardiovascular adaptation and recovery using a murine HU model during three phases over 10 days: 3 days of control, 5 days of HU and 2 days of recovery. Using implantable radio telemetry devices, we continuously collected data on mouse subcutaneous temperature and locomotor activity, as well as cardiac parameters, arterial blood pressure (ABP), heart rate (HR). The cardiac parameters were further exploited to calculate heart rate variability (HRV) and baroreflex sensitivity (BRS). We also performed complementary experiments on 6 subjects to monitor temperature fluctuations. We found that HU induced an immediate, dramatic and persistent decrease in locomotor activity and temperature (subcutaneous and central recorded temperature). On the other hand, the cardiac response was varied. We observed an initial bradycardia associated with an increase in vagal activity and baroreflex sensitivity together with a decrease in water intake. These findings indicate early adaptation to fluid redistribution. Analyses of the complete data set revealed effects on cardiovascular circadian rhythms during HU that are exacerbated during the recovery phase. Our investigation with continuous monitoring has both provided a degree of clarity with regard to the conflicting information in the literature and provided us with insights into how to better design these types of experiments in the future.

Ponemah Physiology Platform Software, DSI, v6.41