Inclusion Criteria:

• * Healthy women between the ages of 18 and 45 years (Controls), taking oral contraceptive or with regular menses every 26-34 days
• * Women between the ages of 18 and 45 years with endometriosis (diagnosis by prior laparoscopy by subject's own physician \<5 years prior, and reported by the subject to the researchers)
• * Tylenol if the subject has acute pain is allowed
• * Contraceptive use is allowed

Exclusion Criteria:

• * Use of nicotine-containing products (e.g. smoking, chewing tobacco, etc.)
• * Diabetes (HbA1C 6.5%)
• * BP\>140/90
• * Taking pharmacotherapy that could alter peripheral vascular control (e.g. insulin sensitizing, cardiovascular medications)
• * Pregnancy
• * Breastfeeding
• * Taking illicit and/or recreational drugs
• * Abnormal liver function
• * Rash, skin disease, disorders of pigmentation, known skin allergies
• * Diagnosed or suspected metabolic or cardiovascular disease
• * Persistent unexplained elevations of serum transaminases
• * Known allergy to latex or investigative substances (including salsalate or simvastatin)
• * History of gastrointestinal bleeding