title: Tolerance to the humoral and hemodynamic effects of caffeine in man.
abstract: Acute caffeine in subjects who do not normally ingest methylxanthines leads to increases in blood pressure, heart rate, plasma epinephrine, plasma norepinephrine, plasma renin activity, and urinary catecholamines. Using a double-blind design, the effects of chronic caffeine administration on these same variables were assessed. Near complete tolerance, in terms of both humoral and hemodynamic variables, developed over the first 1-4 d of caffeine. No long-term effects of caffeine on blood pressure, heart rate, plasma renin activity, plasma catecholamines, or urinary catecholamines could be demonstrated. Discontinuation of caffeine ingestion after 7 d of administration did not result in a detectable withdrawal phenomenon relating to any of the variables assessed.
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D002110:Caffeine / Q000097:blood / Q000494:pharmacology*; D002395:Catecholamines / Q000097:blood* / Q000652:urine; D004311:Double-Blind Method; D004361:Drug Tolerance; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012083:Renin / Q000097:blood*
chemical_list: D002395:Catecholamines; D002110:Caffeine; D012083:Renin