Effect of Heat Shock on the Vascular Reactivity in Diabetic Rat Aorta

Koo, Seong Mo; Lee, Soon Hee; Han, Jung Hun; Jeong, Gi Young; Kim, In Kyum; Kim, Jung Guk; Ha, Sung Woo; Kim, Bo Wan

Abstract

BACKGROUND: Heat shock has been known to change cellular response to noxious stimuli by inducing heat shock proteins (HSP). HSP are expressed in many tissues, and increased expression of some HSP enhances the survival of cells exposed to oxidative stress. Recently, Some HSP are known to associate with vascular reactivity. Under diabetic conditions, there is abnormal vascular reactivity to relaxing or contracting factors. Abnormal vascular response to some stimuli is an important role in the development of diabetic complications. However, the effects of heat shock on the vascular reactivity in diabetic condition is unclear. Therefore, we investigated effects of heat shock on the vascular reactivity in isolated aorta of streptozotocin-induced diabetic rats.
METHODS
After mounced in organ bath, aortic ring preparations were exposed to 42 for 45 minutes followed by being subjected to contraction and relaxation in 4 hours. Tissues were frozen for measurement of HSP 70 and phosphorylation of myosin light chain after functional study.
RESULTS
Heat shock not only increased expression of HSP70 in rat aorta but also augmented contraction to KCl and phenylephrine in the aorta of control and diabetic rats (p<0.05). Relaxation responses to acetylcholine (ACh) were not changed in the aorta of control rats with and without heat shock for 45 minutes. However, heat shock for 45 minutes decreased relaxative responses to ACh in the aorta of diabetic rats compared to those in the aorta of control rats.
CONCLUSION
This result suggests that heat shock increases vascular contractility in the aorta of diabetic and control rats through the induction of HSP70 while heat shock seems to decrease relaxative response in the aorta of diabetic ratscompared to control rats (p<0.05). Whether heat shock impaired relaxative response in the aorta of diabetic rats deserves additional studies.