HEAT SHOCK-INDUCED AUGMENTATION OF VASCULAR CONTRACTILITY IS INDEPENDENT OF RHO-KINASE

SUMMARY 1 In a previous study, we demonstrated that heat shock augments the contractility of vascular smooth muscle through the stress response. 2 In the present study, we investigated whether Rho-kinases play a role in heat shock-induced augmentation of vascular contractility in rat isolated aorta. 3 Rat aortic strips were mounted in organ baths, exposed to 42C for 45 min and subjected to contractile or relaxant agents 5 h later. 4 The level of expression of Rho-kinases in heat shock-exposed tissues was no different to that of control tissues, whereas heat shock induced heat shock protein (Hsp) 72 at 3 and 5 h. Heat shock resulted in an increase in vascular contractility in response to phenylephrine 5 h later. 5 The Rho-kinase inhibitors Y27632 (30 nmol/L-10 mmol/L) or HA 1077 (10 nmol/L-10 mmol/L) relaxed 1.0 mmol/L phenylephrine-precontracted vascular strips in a concentration-dependent manner; these effects were attenuated in heat shock-exposed strips. Pretreatment with Y27632 resulted in greater inhibition of the maximum contraction in control strips compared with those in heat shock-exposed strips. 6 The results of the present study suggest that Rho-kinases are unlikely to be involved in heat shock-induced augmentation of vascular contractility.