Cholinergic contractions of ileal longitudinal smooth muscle in response to a high cholesterol diet and action potential blockade. (A) Effects of cholesterol diet on cholinergic (carbachol) – elicited contractions of the ileum for ground squirrels on a trace (0.027%; Low) vs. enriched (1%; High) cholesterol diet for animals treated with vehicle. (B) Effects of tetrodotoxin (TTX) on cholinergic contractions of the ileum of ground squirrels fed a high (1%) cholesterol diet and treated with vehicle. The action potential blocker tetrodotoxin (TTX; 10-7M) was added to the jejunal tissue segments 10 min before constructing a cumulative dose-response curve to the cholinergic agonist, carbachol. N = 8–9.