This is a three-period crossover study to compare GW876008 and placebo to see if GW876008 will normalise blood flow responses after different emotional stimuli.

Inclusion Criteria:

• The subject should not have been taking and medication for the treatment of IBS for 1 month prior to the study
• Negative serum pregnancy tests (serum a-HCG negative) at Screening (Visit 1), and negative urine pregnancy tests at Visits 1, 2, 3 prior to study medication dose.
• Non-tobacco user (abstinence from tobacco use for at least 1 month before the start of the study).
• Normal electrocardiogram (subjects must have no clinically significant abnormalities on a 12-lead ECG at screen).

Exclusion Criteria:

• Subjects who are pregnant or nursing.
• Current evidence, or history of (at any time in the past) of a biochemical or structural abnormality of the digestive tract. including (but not limited to): inflammatory bowel disease (Crohn's disease or ulcerative colitis); functional dyspepsia; lactose intolerance, not on a stable diet; Celiac Disease
• Subjects who are taking NSAIDs on a regular basis or within 48 hours of a study day.
• The subject has a positive pre-study urine drug/alcohol screen.
• A positive pre-study HIV 1 / 2, Hepatitis B surface antigen or positive Hepatitis C antibody result within 3 months of the start of the study.