The Durk Pearson & Sandy Shaw®
Life Extension NewsTM
Volume 7 No.
4 • September 2004
Possible Antiatherosclerotic Effects of Hot Tubs
The lucky (or unlucky, depending upon your point of view) rats chosen for this study were given 15 minutes of hot water baths daily for 4 weeks to study the effects of heat shock on the development of atherosclerosis.
Previous studies have reported beneficial effects of saunas, including improved vascular endothelial function and cardiac function in chronic heart failure patients in Japan; enhanced endothelial nitric oxide production; suppression of proliferation of vascular smooth muscle cells (VSMCs), as occurs in atherosclerotic lesions; and inhibition of necrotic cell death in VSMCs. Thermal treatment has preconditioning effects against myocardial ischemia/reperfusion injury and is reported to suppress macrophage activation and attenuate inflammatory cytokine production, as well as to release heat-shock proteins that help prevent damage to DNA and other macromolecules.
In this recent study, hollow polyethylene tubes were placed around femoral arteries (“cuffs”) to induce intimal thickening, possibly as a result of the hypoxia resulting from the process. The intima is prone to thickening in atherosclerosis. The experimental animals then received their daily hot baths at temperatures between 40.5ºC (104.9ºF) and 41.5ºC (106.7ºF). Four weeks after the placement of the cuffs, neointima was formed in the subendothelial layers of the arteries in the control animals, while thermal treatment produced a marked reduction in intimal thickening. There was no thickening in control animals that did not receive the cuffs or baths.
The authors found that the thermal treatments resulted in a marked enhancement of expression of heat-shock protein 72 (HSP72) in the adventitia and media of the arteries, regardless of whether they had been cuffed with the hollow polyethylene tubes. The HSP72 had increased expression even after only one bath, and it lasted for at least 72 hours afterward. They also reported an increase in p22-phox, a major component of the oxidative enzyme NADPH oxidase in the cuffed animals, whereas there was little or no p22-phox expression in the thermal-treated arteries of cuffed or noncuffed animals.
- Okada et al. Thermal treatment attenuates neointimal thickening with enhanced expression of heat-shock protein 72 and suppression of oxidative stress. Circulation 109:1763-8 (2004).