Sulfoconjugation of catecholamines, nutrition, and hypertension

Sulfoconjugation is an important metabolic pathway determining the fate and potential cardiovascular action of ingested phenolic substances. Among the three catecholamines, dopamine (DA) is to the highest degree sulfoconjugated and has the highest affinity toward the phenolsulfotransferase (PST). The concentration of some sulfated catecholamines, particularly of DA sulfate, increases following ingestion of catecholamines or their precursors. This can be confounded with blood-derived increases in DA sulfate associated with BP peaks in some hypertensive patients. We mimicked, therefore, the latter condition by infusion of free DA into normotensive subjects. At low DA infusion rates, plasma DA sulfate exceeded free DA concentrations, and there were no changes in blood pressure and pulse rate. At higher DA infusion rates, blood pressure and pulse rate increased only while plasma free DA concentrations exceeded those of DA sulfate, indicating that free DA remains biologically active only prior to being conjugated. A similar increase in DA sulfate from alimentary sources (e.g., eating a banana) remains without cardiovascular response and is not associated with an overflow of free DA, since all the ingested DA is conjugated in the gut. We describe a patient with pheochromocytoma who experienced repeated hypertensive crises after ingestion of food containing some biogenic amines, (once also documented by NE increase), possibly due to a phenol sulfoconjugation defect (e.g., substrate inhibition of the PST or its genetic deficiency). Platelet PST-determinations may serve as a screening tool to detect subjects with sulfoconjugation defects since they probably reflect the PSt activity in the gut where ingested phenols are sulfoconjugated.