Figure 6.

Vasomotor responses to ATP in penetrating arterioles of 3, 6 and 12 months old Tg2576 and WT litter mates and attenuation of Aβ_1-40 induced vessel constriction by 4G8 antibody. Vasomotor responses to extraluminal ATP were measured in cerebral arterioles of control littermate and TG2576 mice ex vivo. (A) At three months of age, the vessels show strong responsiveness to extraluminal ATP both in Tg2576 and WT-LM. At six months, dilation to ATP is reduced in Tg2576 mice. At 12 months, vasomotor responses in Tg2576 vessels are greatly reduced and the vessels show smooth muscle cells enveloped by amyloid. Insert: Thioflavin-S staining of an arteriole (44 μm diameter) from a Tg2576 mouse used in the experiments. * denotes p > 0.05 from WT at same age. (B) Incubation with Aβ_1-40 caused a significant arteriolar constriction which lasted at least for 30 minutes after washout. The soluble Aβ-specific antibody 4G8 restored control vessel tone while the control IgG did not. * = p < 0.05 from tone diameter for both control IgG and 4G8 treated vessels; t = p < 0.05 from Aβ_1-40-induced constriction; n.s = not significant from Aβ_1-40-induced constriction.