title: Cardiovascular responses to submaximal arm and leg exercise in cardiac transplant patients.
abstract: We examined whether an increase in stroke volume (SV) contributes to the increase in cardiac output that occurs when cardiac transplant patients (CT) exercise between 50% and 75% of maximum. Upright arm and leg exercise was performed by 13 CT and 10 normal controls. Cardiac output (CO2 rebreathing), expired air, and catecholamine measures were obtained at rest and at 50% and 75% of maximum. From rest to 50% of maximum both normals and CT increased heart rate (HR) and SV during arm and leg exercise. In normals, HR (arm = +17 +/- 2 min-1; leg = +21 +/- 3 min-1) was increased further at 75% of maximum but not SV (arm = 3 +/- 4 ml; leg = +2 +/- 8 ml). In CT, further increases in both HR (arm = +9 +/- 1 min-1; leg = +13 +/- 1 min-1) and SV (arm = +12 +/- 5 ml; leg = +12 +/- 3 ml) were observed at 75% of maximum. During leg exercise plasma norepinephrine was increased more in CT than in normals. Between 50% and 75% of maximum, an increase in SV is a more important mechanism for increasing cardiac output during upright arm and leg exercise in CT than in normals.
authors.affiliation: Henry Ford Heart and Vascular Institute, Detroit, MI 48202.
authors.forename: S J
authors.initials: SJ
authors.lastname: Keteyian
authors.forename: C R
authors.initials: CR
authors.lastname: Marks
authors.forename: A B
authors.initials: AB
authors.lastname: Levine
authors.forename: T
authors.initials: T
authors.lastname: Kataoka
authors.forename: F
authors.initials: F
authors.lastname: Fedel
authors.forename: T B
authors.initials: TB
authors.lastname: Levine
mesh_terms: D001132:Arm / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D002302:Cardiac Output / Q000502:physiology; D004562:Electrocardiography; D004837:Epinephrine / Q000097:blood; D005080:Exercise Test; D006339:Heart Rate / Q000502:physiology*; D016027:Heart Transplantation / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology; D009638:Norepinephrine / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D012119:Respiration / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide; D009638:Norepinephrine; D004837:Epinephrine