Cardiovascular responses to heat and cold exposure are altered by preterm birth in guinea pigs

Adversity early in life can modify the trajectory for disease risk extending decades beyond the event. Preterm birth produces persistent cardiovascular alterations that may appear maladaptive in adulthood. We have previously hypothesized that those born preterm may exhibit cardiovascular vulnerability in the climate change context. Further, this vulnerability may be present as early as childhood. We aimed to identify the early signs of cardiovascular dysfunction at childhood-equivalent age using our animal model of preterm birth. Using a whole-body thermal stress test, guinea pigs aged 35-d and 38-d (equivalent to 8-10-year-old children) and born at term or preterm gestations were exposed to progressive hyper- (T_C = 41.5°C) and hypo-thermia (T_C = 34°C; normothermia T_C = 39°C). Comprehensive cardiovascular monitoring included ECG, blood pressure, microvascular perfusion, blood gas, and catecholamine profile, as well as skin and core body temperature. Preterm-born animals exhibited attenuated vascular responses to hyperthermic stress, and a significant elevation in systolic blood pressure in response to hypothermic stress. Such responses are similar to those observed in elderly populations and indicate the presence of cardiovascular dysfunction. This is the first study to demonstrate the impact of preterm birth on the cardiovascular response to both heat and cold stress. Further, this dysfunction has been observed at an earlier age than that achievable using traditional stress testing techniques. The present findings warrant further investigation.