Acetylsalicylic acid (ASA; 0.1–10 mg/kg), indomethacin (IND; 0.1–1.0 mg/kg), and tartrazine (TZ; 0.1–2.0 mg/kg), given intravenously induced dose-dependent increases in carotid-sinus nerve (CSN) activity, accompanied by increases in mean arterial blood pressure (MABP), but only the IND-induced MABP increases were dose-dependent. The MABP and CSN activity responses to all three drugs were not correlated, suggesting a direct action on CSN afferents that is unrelated to the pressor effects of the drugs. Sodium cromoglycate (10 mg/kg) selectively reduced the increases in CSN response to ASA and IND. Phentolamine (0.2 mg/kg) inhibited the increased CSN activity induced by ASA, IND, and TZ. These findings indicate that ASA, IND, and TZ act directly on carotid baroreceptors to increase their act