Microvascular responses of intermediate-size arterioles on the cerebral surface of diabetic mice

Mice were rendered diabetic with streptozotocin. After intervals of approximately 4 weeks and 6 months, the vascular responses of cerebral surface arterioles (pial arterioles) with mean internal diameters of 35-39 micrometers were determined and compared with those of control mice. Norepinephrine, serotonin, prostaglandin F2 alpha, and papaverine were used. Only one agent was tested in a given mouse, each agent being applied to the surface vessels of that mouse at three different doses. Statistically significant dose-response relationships were always observed, but with one exception, no differences were found between the contractile responses (norepinephrine, serotonin, prostaglandin F2 alpha) or the dilating responses (papaverine) in diabetic vs normal mice. The one exception involved responses to serotonin following 4-5 weeks of diabetes. Here diabetic responses were 10-18% less than those of control. Though significant statistically, the difference may nevertheless be a chance occurrence, and is in any case sufficiently small to be of doubtful biological meaning. The overall data indicate no effect of diabetes on the responses of the selected pial arterioles to norepinephrine, serotonin, PGF2 alpha, and papaverine.