EFFECT OF CIGARETTE-SMOKE EXTRACT ON ARTERIOLAR DILATATION IN-VIVO

The goal of this study was to determine whether cigarette smoke extrac t alters dilatation of arterioles in vivo in response to agonists that produce activation of ATP-sensitive potassium channels and activation of adenylate cyclase. By using intravital microscopy, we measured dia meter of arterioles contained within the microcirculation of the hamst er cheek pouch during suffusion with agonists in the absence and prese nce of cigarette smoke extract (0.1, 0.5, and 1.0%). Before treatment with cigarette smoke extract, activation of ATP-sensitive potassium ch annels with aprikalim and cromakalim produced dose-related dilatation of cheek pouch arterioles, Similarly, activation of adenylate cyclase with isoproterenol and forskolin produced dose-related dilatation of c heek pouch arterioles before treatment with cigarette smoke extract. S uperfusion of 0.1% cigarette smoke extract did not change baseline dia meter of arterioles and did not alter responses of cheek pouch arterio les to activation of ATP-sensitive potassium channels and adenylate cy clase. Superfusion of 0.5 and 1.0% cigarette smoke extract also did no t alter baseline diameter of arterioles but did impair dilatation of a rterioles in response to activation of ATP-sensitive potassium channel s and adenylate cyclase. These findings suggest that cigarette smoke e xtract impairs dilatation of resistance arterioles in response to acti vation of important cellular dilator pathways.