title: Altered autonomic mechanisms in the sick sinus syndrome and diurnal variations in the parameters of sinus node function.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001285:Atropine / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001794:Blood Pressure; D002304:Cardiac Pacing, Artificial; D002940:Circadian Rhythm; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D011433:Propranolol / Q000494:pharmacology; D012804:Sick Sinus Syndrome / Q000503:physiopathology* / Q000628:therapy; D012849:Sinoatrial Node / Q000503:physiopathology*; D013997:Time Factors; D014636:Valsalva Maneuver
chemical_list: D001285:Atropine; D011433:Propranolol; D007545:Isoproterenol