Figure 9.

Determination of site(s) of action of coffee on smooth muscle contractions in the colon. Colonic muscle strips were isolated from naïve rats, and their longitudinal muscle contractile activities were recorded in the muscle bath. The contractile response to regular coffee (Coff) and decaffeinated coffee (Decaf) at 5 mg/mL was recorded in the absence and presence of the nicotinic receptor antagonist hexamethonium (Hex) (A), the muscarinic receptor antagonist atropine (Atr) (B), and the neurotoxin tetrodotoxin (TTX) (C). Tracings are representative of 4~5 independent experiments. The response in the first 2 min after the addition of coff or decaf over baseline activity is summarized in the bar graphs. N = 4 or 5. * p < 0.05.