[Vascular reflex in microcirculation of hamster cheek pouch model]

The vascular reflex in hamster cheek pouch model was studied. When temperature of the superfusing solution was changed from 37 degrees C, diameter of small artery was increased up to 45 degrees C; instead, the diameter was decreased at the temperature below 37 degrees C to 14 degrees C. These responses of small artery were temperature-dependent. The dilatation of small artery by increasing or decreasing pH from 7.35 was demonstrated. The pH-dependent response of the small artery was found over the pH range of 7.0-8.5 or of 7.0-5.85. By the temperature (45 degrees C and 14 degrees C) or pH (8.5 and 5.85) stimulation of the cheek pouch preparations, the small artery in opposite preparation superfused at 37 degrees C or at pH 7.35 was responded after a few minute latency in a manner analogous to that seen in the stimulated cheek pouch preparations. The reflex dilatation produced by the stimulation with pH 5.85 was significantly inhibited by the treatment of hamster with atropine, suggesting that the vascular reflex are from the stimulated preparations to opposite non-stimulated preparations may be the long path reflex at least in part via parasympathetic nerves. It is also demonstrated that the potency of the sensitivity of the microvessels to pH and temperature changes is in following orders: small artery (A1) greater than arteriole (A2) greater than terminal arteriole (A3) and A2 = A3 greater than A2, respectively.