Restoration Of Body Temperature Research Articles

Autonomic Nervous System Response to Far-Infrared Sauna Exposure in Firefighters.

Fire departments have employed far-infrared sauna (FIRS) use as part of post-fire call protocols to address concerns related to carcinogens. The inability of the autonomic nervous system (ANS) to fully recover following an emergency call, as demonstrated by heightened sympathetic nervous system activity and delayed parasympathetic nervous system reactivation, has been implicated as a potential factor related to sudden cardiac death. The use of a sauna post-fire call, which has been demonstrated to elevate body temperature, may interfere with the ability of the ANS to fully recover. The purpose of this study was to examine ANS responses to FIRS exposure in firefighters (FFs) with (EX) and without (NONEX) prior maximal exercise. Sixteen career FFs participated in this study. Body temperature (TEMP), heart rate (HR), heart rate variability (HRV), blood pressure (BP), and blood lactate (La─) were measured at the start of each testing session, following a maximal exercise test (EX only), and immediately after a 15-min FIRS exposure for NONEX and EX. In NONEX, TEMP increased (P < 0.001); however, there was no change in HR, HRV, BP, or La─. In EX, BP remained unchanged while TEMP, HR, and La─ were significantly (P < 0.001) greater than baseline following FIRS exposure and HRV was significantly (P = 0.018) lower than baseline. These findings indicate that FIRS following maximal exercise did support some ANS recovery, but may interfere with restoration of body temperature and parasympathetic nervous system reactivation, potentially influencing post-call cardiovascular risk in FFs.

Effects of Acute Cooling on Expression of Genes for Thermosensitive TRP Ion Channels in the Hypothalamus

Acute cooling of the body was found to have different effects on the expression of thermosensitive TRP ion channel genes in the hypothalamus which depended on the cooling rate. Slow cooling of the body affected the expression of genes for two types of thermosensitive TRP ion channels in the hypothalamus – TRPV3 and TRPM8. Changes in gene expression did not occur simultaneously – Trpv3 gene expression increased at the peak of cooling, when thermoregulatory reactions develop, while that of the Trpm8 gene increased on restoration of body temperature after cooling. Rapid cooling at the peak of the thermoregulatory reaction had no effect on expression of genes for thermosensitive TRP ion channels in the hypothalamus. On restoration of body temperature after rapid cooling, activity in the Trpm8 gene in the hypothalamus increased. Thus, acute temperature exposure affected processes occurring at the level of the genome and dynamic changes in the expression of TRP ion channel genes in the hypothalamus may be one of the mechanisms of adaptation to changes in temperature conditions.