Hypothermia down-regulates the LPS-induced norepinephrine (NE) release in ischaemic human heart cells

Hypothermia has been widely acknowledged as the fundamental component of myocardial protection during cardiac operations. In this work, we studied in human atrial tissue the effect of the common hypothermic protection used in cardiac surgery, and we assessed this effect by comparing catecholamine release among normoxic, ischaemic, and inflammatory conditions. Our results provide the first evidence that lipopolysaccharide treatment results in an extremely dramatic and significant increase in the resting norepinephrine release under ischaemic conditions that can be normalised by hypothermia. These findings demonstrate that inflammatory conditions increase the temperature sensitivity of the norepinephrine transporter in human cardiac tissue. When the possible pharmacological interventions are taken into consideration, the results presented here provide new insight into the protection against ischaemia/reperfusion injury during cardiac surgery.