title: Attenuated pre-ejection period response to tyramine in patients with cardiac sympathetic denervation.
abstract: Stress is a well-known factor affecting cardiac contractility through the cardiac sympathetic nerves. A positive inotropic effect of the cardiac sympathetic nerves on the myocardium is reflected by pre-ejection period (PEP) shortening. Patients with Parkinson disease (PD) and neurogenic orthostatic hypotension (NOH) (PD + NOH) or with pure autonomic failure (PAF) have markedly decreased myocardial 6-[(18)F]Fluorodopamine-derived radioactivity, reflecting cardiac sympathetic denervation. The functional effects of the cardiac sympathetic denervation have been unknown. We measured PEP and heart rate-corrected PEP (PEPI) responses to i.v. tyramine (1 mg/min) in 13 patients (9 PD + NOH and 4 PAF) with low 6-[(18)F]Fluorodopamine-derived radioactivity and in subjects with normal radioactivity (15 multiple system atrophy with NOS patients (MSA + NOS). Baseline PEP and PEPI did not differ between the groups. By 10 min after initiation of tyramine infusion, PEP and PEPI were significantly lower (P < 0.01) in MSA + NOS, compared to base line, whereas PEP and PEPI remained unchanged in the PD + NOH/PAF group. The PEP and PEPI decrease was larger in the MSA + NOS group than in the PD + NOH/PAF group (P < 0.05). One of the functional consequences of cardiac sympathetic denervation is failure to increase contractility in response to stimuli that depend on endogenous norepinephrine release.
authors.affiliation: Clinical Neurocardiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA. richard.imrich@savba.sk
authors.forename: Richard
authors.initials: R
authors.lastname: Imrich
authors.forename: Basil A
authors.initials: BA
authors.lastname: Eldadah
authors.forename: Oladi
authors.initials: O
authors.lastname: Bentho
authors.forename: Sandra
authors.initials: S
authors.lastname: Pechnik
authors.forename: Yehonatan
authors.initials: Y
authors.lastname: Sharabi
authors.forename: Courtney
authors.initials: C
authors.lastname: Holmes
authors.forename: David S
authors.initials: DS
authors.lastname: Goldstein
mesh_terms: D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D005260:Female; D006321:Heart / Q000294:innervation* / Q000502:physiology* / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology; D013562:Sympathectomy; D013566:Sympathomimetics / Q000494:pharmacology*; D014439:Tyramine / Q000494:pharmacology*
chemical_list: D013566:Sympathomimetics; D014439:Tyramine