title: Endothelial dysfunction and circadian blood pressure rhythmicity in young heart transplant recipients.
abstract: Blood pressure variability correlates with circadian rhythmicity in endothelium-derived nitric oxide (NO) production in adults. Young, hypertensive orthotopic heart transplant (OHT) patients have functional abnormalities in NO-dependent signaling pathways that lead to reduced NO bioavailability and endothelial dysfunction. Following acute intravenous infusion of L: -arginine, the amino acid substrate for NO, OHT patients normalize blood pressure (BP) and endothelial function. However, the effects of chronic L: -arginine infusion on circadian BP rhythmicity and endothelial function in OHT patients have not been described. Six OHT patients (9-29 years old), and seven healthy control subjects (19-28 years old) were admitted for 48 hours. Systolic, diastolic, and mean blood pressures (MBP) were recorded hourly. Urine samples were obtained to measure nitrates/nitrites (NO(X)). Brachial artery flow-mediated vasodilatation (FMD; an index of endothelial function) and left ventricular ejection fraction (LVEF) were measured 0, 23, and 48 hours after admission. Intravenous L: -arginine HC1 was infused continuously beginning 24 hours after admission in all subjects. The incidence (50%) and degree (12.0 +/- 9.2%) of nocturnal MBP dipping was significantly less in OHT patients than control subjects. Furthermore, FMD was significantly reduced in OHT patients compared to controls (3.2 +/- 1.1 vs 7.2 +/- 3.1%, p = 0.01). L: -Arginine infusion had no significant effect on 24-hour MBP, LVEF, or nocturnal dipping status in any subject; however, L: -arginine normalized FMD in OHT patients (7.4 +/- 1.8%). Circadian BP variability and endothelial function are impaired in young cardiac transplant patients with medically controlled hypertension, and L: -arginine administration reverses endothelial dysfunction.
authors.affiliation: Division of Pediatric Cardiology, C.S. Mott Children's Hospital, University of Michigan, 1500 E. Medical Center Drive, Ann Arbor, MI 48109-0204, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Parra
authors.forename: D Scott
authors.initials: DS
authors.lastname: Lim
authors.forename: Carolyn L
authors.initials: CL
authors.lastname: Buller
authors.forename: John R
authors.initials: JR
authors.lastname: Charpie
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001120:Arginine; D001794:Blood Pressure / Q000187:drug effects*; D016022:Case-Control Studies; D002648:Child; D002940:Circadian Rhythm / Q000187:drug effects*; D004727:Endothelium / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D009569:Nitric Oxide; D013997:Time Factors; D014180:Transplantation
chemical_list: D009569:Nitric Oxide; D001120:Arginine