title: Challenging cardiac function post-spinal cord injury with dobutamine.
abstract: There is general consensus that spinal cord injuries (SCI) above T6 result in altered sympathetic control of the heart, which negatively influences cardiac structure and function. To by-pass disrupted circuitry and investigate cardiac responses under enhanced sympathetic activity we utilized dobutamine (DOB) stress echocardiography. Animals were divided into a T2, 25g-cm contusive SCI (SCI) or an uninjured control (CON) group. Echocardiography was performed pre-SCI and at 1, 2 and 6weeks post-SCI. Increasing doses of DOB (5, 10 & 20μg/min/kg) were infused intravenously pre-SCI and at 1 and 6weeks post-SCI. Parasternal-short axis images were used to compare group differences in systolic function and track changes in response to SCI and DOB over time. One week post-SCI, stroke volume (SV), end diastolic volume (EDV), cardiac output (CO) and ejection fraction (EF) were all reduced compared to CON and these deficits persisted to 6weeks. We also found an increase in collagen deposition at 6weeks post SCI. Pre-SCI, DOB elicited a decrease in EDV and increases in CO, EF and HR but not SV. At 6weeks following SCI, in addition to increases in CO, EF and HR, DOB also induced increases in SV. This is the first report, to our knowledge, of DOB responses in a contusive SCI model with persistent cardiac impairments. The return of CO to pre-SCI levels and the substantial increase in SV at low DOB dosages shows that impaired descending control of the heart is directly contributing to reduced resting SV after SCI.
authors.affiliation: Anatomical Sciences & Neurobiology, University of Louisville, Louisville, KY, United States; Department of Neurological Surgery, University of Louisville, Louisville, KY, United States. Electronic address: kmdeve01@louisville.edu.
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: DeVeau
authors.affiliation: Department of Neurological Surgery, University of Louisville, Louisville, KY, United States. Electronic address: emily.martin.2@louisville.edu.
authors.forename: Emily K
authors.initials: EK
authors.lastname: Martin
authors.affiliation: Department of Neurological Surgery, University of Louisville, Louisville, KY, United States. Electronic address: nicholas.king@louisville.edu.
authors.forename: Nicholas T
authors.initials: NT
authors.lastname: King
authors.affiliation: Department of Neurological Surgery, University of Louisville, Louisville, KY, United States. Electronic address: alice.shumsiu@louisville.edu.
authors.forename: Alice
authors.initials: A
authors.lastname: Shum-Siu
authors.affiliation: Biomedical Engineering, University of Louisville, Louisville, KY, United States; Kosair Charities Division of Pediatric Heart Research, University of Louisville, Louisville, KY, United States. Electronic address: brad.keller@louisville.edu.
authors.forename: Bradley B
authors.initials: BB
authors.lastname: Keller
authors.affiliation: School of Kinesiology, Faculty of Education, University of British Columbia, Vancouver, BC. Canada; International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada. Electronic address: west@icord.org.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: West
authors.affiliation: Anatomical Sciences & Neurobiology, University of Louisville, Louisville, KY, United States; Department of Neurological Surgery, University of Louisville, Louisville, KY, United States; Biomedical Engineering, University of Louisville, Louisville, KY, United States. Electronic address: david.magnuson@louisville.edu.
authors.forename: David S K
authors.initials: DSK
authors.lastname: Magnuson
mesh_terms: D000818:Animals; D002302:Cardiac Output / Q000187:drug effects*; D004280:Dobutamine / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006801:Humans; D009200:Myocardial Contraction / Q000187:drug effects; D013119:Spinal Cord Injuries / Q000188:drug therapy* / Q000503:physiopathology; D013318:Stroke Volume / Q000187:drug effects
chemical_list: D004280:Dobutamine
keywords: Cardiac; Echocardiography; Spinal cord injury