Repeated thermal therapy upregulates arterial endothelial nitric oxide synthase expression in syrian golden hamsters

It has been previously reported that sauna therapy, a thermal therapy, impr oves the hemodynamics and clinical symptoms in patients with chronic heart failure and also improves endothelial function, which is impaired in such p atients. The present study investigated whether the improvements observed w ith sauna therapy are through modulation of arterial endothelial nitric oxi de synthase (eNOS) expression. Eight male Syrian golden hamsters underwent sauna therapy, using an experimental far infrared-ray dry sauna system at 3 9 degreesC for 15 min followed by 30 degreesC for 20 min daily for 4 weeks. Control group hamsters were placed in the sauna system switched off at roo m temperature of 24 degreesC for 35 min. Immunohistochemistry found greater amounts of the immunoreactive products of eNOS in the endothelial cells of the aorta and carotid, femoral and corollary arteries in the sauna group t han in the control group. Western blot analysis also revealed that 4-week s auna therapy significantly increased eNOS expression in aortas by 50% in 4 series of independent experiments with an identical protocol (p<0.01). In r everse transcription polymerase chain reaction assay, the eNOS mRNA in aort as was greater in the sauna group than in controls, with a peak at 1-week o f sauna therapy (approximately 40-fold increase). In conclusion, repeated t hermal therapy upregulates eNOS expression in arterial endothelium.